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Expert Questions & Answers


Active Experts

 

Tony Gill Rick Karg Bob Scott Cal Steiner
 



Category: Monitoring
Subject: ASHRAE 62.2 Kitchen Ventilation

Question: When using the Alternative Compliance Path for kitchen ventilation, does this give any leeway for not installing any spot ventilation inside of a kitchen if it does not exist or the existing exhaust ventilation cannot be vented to the outside?   I have a 20 square meter kitchen. I want to install a proper exhaust system. The duct length is about 40 ft. What is the best solution?

Answer:   The Alternative Compliance Path for existing homes allows 1) no local (spot) ventilation in a kitchen or 2) existing exhaust ventilation that is less than 100 CFM actual flow rate. A recirculating range hood is the same as no local ventilation in a kitchen.

 

When using the Alternative Compliance Path, the total deficit of local ventilation (bathrooms and kitchens) must be added together and then divided by 4 to get the alternative compliance supplement. This alternative compliance supplement is then added to the whole-building ventilation rate in order to compensate for the deficiencies of local ventilation. The method for determining the local ventilation deficits are found in Appendix A of ASHRAE 62.2-2010.

The best fan for a kitchen is a range hood. According to the ASHRAE 62.2 standard (
  Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings)  you will need a range hood with an actual flow rate of at least 100 CFM (47 L/s). Based on Table 5.3, Prescriptive Duct Sizing, in ASHRAE 62.2-2-10 you will need to use 5-inch (125 mm) smooth duct for your 40 foot (12 m) run. According to the table, you have some room to spare; this duct size allows you to make a run of 85 feet (28 m).

-Rick Karg

Category: Technical Tools
Subject: Exhaust fan size for kitchen

QuestionI have a 20 square meter kitchen. I want to install a proper exhaust system. The duct length is about 40 ft. What is the best solution?

AnswerThe best fan for a kitchen is a range hood. According to the ASHRAE 62.2 standard ( Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings) you will need a range hood with an actual flow rate of at least 100 CFM (47 L/s). Based on Table 5.3, Prescriptive Duct Sizing, in ASHRAE 62.2-2-10 you will need to use 5-inch (125 mm) smooth duct for your 40 foot (12 m) run. According to the table, you have some room to spare; this duct size allows you to make a run of 85 feet (28 m).

-Rick Karg

Category: Health & Safety
Subject: CO and Draft tests

Question: Does DOE or WAPTAC offer any guidance regarding drilling Type-B (double-wall) gas vent pipe to perform CO and/or draft tests? (A) The major pipe manufacturers suggest drilling the outer hole larger than the inner hole, and then sealing the inner and outer holes with RTV silicone. (B) Another possible technique I've seen is to seal both holes with a stainless steel bolt, with RTV applied on the threads to better seal the inner hole. Is there any combustion appliance testing protocol that recognizes either of these techniques [(A) and/or (B)]?

Answer: I am not aware of any official protocol for the drilling of double-wall vent pipe. There is something I am wondering about: are you actually asking about B-vent pipe or are they are they referring to the double-wall pipe configuration used for mobile home furnaces, which is technically not B-vent, but a piping system where the exhaust gases exit through the inner pipe and the supply air for the furnace passes through the space between the inner and outer concentric pipes? Regardless, there is no standard protocol I am aware of.

If you are talking about B-vent, I think either of the methods mentioned is fine.

For the mobile home concentric vent configuration, I prefer using a black pipe threaded nipple and cap that is long enough to span the space between the two pipes (see the attached scan here. The cap is in a small plastic bag). A hole is drilled in both pipes. The hole must be the right diameter so that the nipple thread will fit snuggly. Then the hole in the outer pipe is made slightly larger. Put some high-temp. caulking on the nipple threads and thread it into the hole in the inner pipe. Then caulk the outer pipe nipple/hole area. Put the nipple cap on when done with test. Wisconsin Wx uses this method. Some state codes, as far as I know, will not allow it.

-Rick Karg



Category: Health & Safety
Subject: Acceptable garage-to-home isolation

Question: When testing a home to determine an acceptable or unacceptable connection between the garage and living space, does WAP reference a threshold using ZPD? For example, if a home is being depressurized at -50 Pascals, is it "acceptable" if the garage is at 48 pa (i.e., almost completely outside) but not "acceptable" if it is at 38 pa)? On a related issue, is it reasonable to expect a well performing home (e.g., a new home built to ENERGY STAR specs) will have less than a 5 pa connection between the garage to home (based on any empirical data)?

Answer: To my knowledge, the WAP program does not reference a pressure threshold for the connection between an attached garage and a house, except for the State of Maine (there might be other State low-income programs I am not aware of that have thresholds). The Maine Weatherization Standards 2011 state:

  • Post-weatherization leakage between the house and garage (house-to-zone using open-a-door ZPD method) should be 200 CFM50 or less.
  • Exceptions:
  • If the garage has been converted to a living space, this testing is not required.
  • If the garage is not able to be fully enclosed, this testing is not required.
  • If the configuration of the attached or tuck-under garage makes ZPD testing impossible. For example, if an attached garage is also connected to the dwelling attic space. In such cases, the reason for not testing must be included in the client file.

Notice that this Maine threshold is NOT a pressure difference, but a flow – 200 CFM50 or less. It is my opinion that thresholds such as this should never be stated as pressure differences because the pressure differences are relative to one another. For example, if the pressure difference between the house and the garage is 40 Pa, the pressure difference between the garage and outdoors will be 10 Pa. The two pressure differences will always add up to 50 pascals, the pressure created by the blower door. If I want to make this example pressure difference between the house and garage look better, I can do so without any air sealing; all I have to do is make some new holes in the pressure boundary between the garage and the outdoors. Making these new holes will lower the pressure difference between the garage and outdoors, say to 4 Pa, and increase the pressure difference between the house and garage to 46 Pa. The point here is that NOTHING was done to tighten the pressure boundary between the house and garage, but things seem better. However, they are not.

So, I can’t honestly answer your first question because I don’t think it is valid to use a threshold based on pressure differences, but using flow rates – like 200 CMF50 or less between the house and garage – is fine. By the way, the Maine threshold or 200 CFM50 represents approximately 20 square inches of leakage.

The second question regarding new EnergyStar home leakage rates to an attached garage is difficult to answer. I am not aware of any empirical studies of house-to-garage pressure differences or of flow rates between a house and an attached garage. Of course, pressure differences can be measured and they are the first part of zone pressure testing, but testing should always include the second step of opening a hole or door to determine the flow rates between the house and garage.

-Rick Karg



Subject: Energy Education

Question: For ASHRAE 62.2 Can We Use Make Up Air Through A Central System To Meet The New Guideline? In Multi-Family It Is CoStly InStall Fans. ThankYou!

Answer: Yes, you may us outdoor makeup air through a central furnace or air conditioner (air handler) to satisfy the requirements for ASHRAE 62.2 whole-building ventilation. This is usually done by installing a new duct from the outdoors to the return plenum of the air handler. It is best to install a motorized damper in this duct with a control that will close it when ventilation air is not needed.

As with most options, there are some advantages and disadvantages with this method. First, the disadvantages.
  1. This type of ventilation pressurizes the dwelling when the outdoor air damper is open and the air handler is running. In cold climates, pressurizing a dwelling is usually not recommended. However, pressurizing a dwelling in other climates warmer climates is generally not a problem.
  2. Controlling the amount of ventilation from this type of system can be a challenge. The air handler operation is controlled by the need for heating or cooling, rather than by the need for fresh ventilation air. So without the proper controller, when it is very cold or very warm outdoors, the air handler runs often and the house is over ventilated. This can waste energy. On the other hand, during the swing seasons of spring and fall when the air handler does not run as much, the dwelling might be under ventilated. There are controls available that address these problems; the AirCycler g2-k is an example.
  3. A separate fan might be required to provide the proper ventilation rate during the swing seasons.
What about the advantages?
  1. This can be a relatively inexpensive way to provide for ventilation if done properly. If you haven’t installed a system like this before, it is wise to get the advice of installers who have, and from the manufacturers of controls.
  2. Because the ventilation air is ducted throughout the dwelling by the ductwork, the fresh air is well distributed. This is a distinct advantage over a single exhaust or supply fan.
  3. The incoming ventilation air is filtered by the air handler filter.
  4. Because this system pressurizes the dwelling while the air handler is operating, it does not cause problems with the venting of combustion appliances. It does not come into play during your combustion safety testing, as long as the return-side ductwork is sealed.
The use of this method should be considered for any single-family or multifamily dwelling that has an air handler. Weigh the pros and cons, talk with experienced installers and manufacturers, and find the right equipment. As the ASHRAE 62.2 Standard is adopted by more programs and jurisdictions, it is likely that this method of providing ventilation will become more common.

-Rick Karg


Category : Health and Safety
Subject: Worst Case Caz Limits
 
Question: What is the best solution (economical & practical) to a caz that exceeds depressurization limits, but still passes draft & spillage tests?
 
Answer: The answer to this question depends on the program you are working with. The protocols for some programs require that the CAZ depressurization not exceed the safe appliance depressurization limit. For example, if the CAZ depressurization is -3 pascals, the appliance depressurization limit must be greater than -3 pascals, say -5 pascals. Of course, when the CAZ depressurization is too low for an appliance, the depressurization can be lessened (this is often difficult to do) or the appliance can be replaced by one that is more resistant to depressurization problems, such as a direct-vent unit. Other programs will allow excessive CAZ depressurization if the appliance still drafts properly and shows no sign of spillage.
 
The worst-case depressurization testing we perform with vented appliances is sometimes referred to as stress testing. We stress the appliance, that is, we subject it to the lowest realistic negative pressure. Research has demonstrated that stress tests “. . . should be interpreted with caution, as they tend to over predict the number of spillage prone houses and results vary significantly with outdoor conditions” (Rapp, V.H et al. Assessment of Literature Related to Combustion Appliance Venting Systems. LBNL, June 2012).
 
The only other method of testing appliance venting is to monitor spillage and venting over a long period during varying weather conditions. This long-term, expensive testing is not practical for typical weatherization, so we are left with stress testing and doing our best to interpret the results correctly.
 
So the first order of business is to follow the protocol of your program. If your protocol states that passing the spillage and draft test trump the depressurization test, abide by this. If your protocol states that failure of the depressurization test requires a particular action, even if the draft and spillage tests are OK, abide by this.
 
On the other hand, if your program protocol does not clearly state what to do with a condition characterized by a failed depressurization test, even though the spillage and draft tests are OK, I would proceed with caution. It could be that the weather conditions were favorable during your testing, favorable in a manner that yielded good spillage and draft tests. It might be that with a change in the weather conditions, one or both of these tests might fail. A failed depressurization test usually warrants caution. Take steps to reduce the negative pressure in the CAZ or consider replacing the appliance with one that is more resistant to draft problems.

-Rick Karg
 

Category : Technical Tools
Subject: Retrofitting wood fireplaces in multifamily housing
 
Question:I am working with a building owner that has several large MF developments with fireplaces. Are you aware of any electric fireplace retrofits? And what has been people's experience with them?
 
Answer: Yes, there are electric fireplace inserts that work. No, I know of no one in WAP – or in any other efficiency program – who has found them beneficial. If this is WAP, I don’t see how an electric fireplace would pass the savings-to-investment-ratio test (SIR = 1.0) unless the fireplace is necessary to heat the place and wood is VERY expensive. Electric fireplaces (or any kind of electric heating except heat pumps) are not efficient.

And I’m not sure why he wants to address fireplaces. Are they a primary or required secondary heating source? That would be unusual in a multifamily building.
 
-Glen Salas
 

Category : Technical Tools
Subject: ASHRAE 62.2
 
Question: I have a three part question. If you install a ASHRAE fan, do you need to also install an Client "override" switch? How do you install an ASHRAE compliant bathroom fan in a older mobile home? Finally, is there a threshold, such as if a home needs 10 cfm continious, can this be accomplished through Client education? So, 10 cfm or less would come through Client Ed? I beleive other States may have address this, but Tennessee has not.
 
Answer: If you install a ASHRAE fan, do you need to also install an Client "override" switch?

Section 4.4 of ASHRAE 62.2-2010 states: “Readily accessible [whole-building fan] override control must be provided to the occupant. Local exhaust fan switches and ‘fan on’ switches shall be permitted as override controls. Controls. . . must be appropriately labeled.” My interpretation of this section is that an override switch must be provided for a whole-building ventilation fan and it must be labeled regarding the purpose it serves.

I have been asked if a labeled circuit breaker in the electrical panel qualifies as a “readily accessible override control”. It is my opinion that it does not because it is not “readily accessible”.

How do you install an ASHRAE compliant bathroom fan in an older mobile home?

The usual problem here is the fan must have a shallow profile to fit in the shallow ceiling joist space in a mobile home. Broan and Panasonic make some bathroom fans with less than a 4-inch height and 3-inch duct that also comply with the ASHRAE 62.2 sound requirement of 3 sones or less.

Finally, is there a threshold, such as if a home needs 10 CFM continuous, can this be accomplished through Client education? So, 10 CFM or less would come through Client Ed? I believe other States may have address this, but Tennessee has not.

No, there is nothing in the ASHRAE 62.2-2010 standard that allows the substitution of client education for low fan CFM requirements. I am not aware of any states that are allowing this. Because DOE is requiring State low-income weatherization programs to follow ASHRAE 62.2 to the “fullest extent possible” (WAP 11-6, page 9), my assumption is that DOE will NOT allow this substitution of low CFM values by client education.
 
- Rick Karg
 

Subject : Crawlspaces
 
Question: I have a one story 8 unit multi family building that i am working on and it has a 3' crawlspace under the building. The dimensions of the crawlspace is 54 x 112 x 3'= 18,144 cu ft. It has vapor barrier on the exposed dirt but not attached to the walls. I am planning on extending the vapor barrier up onto the wall and totally seal it. There are 10 - 8 x16" vents that are passive. Should I close up the vents and install mechanical exhaust only ventilation, and if so, how much do i need? What codes or formulas do i need to use to size the exhaust only ventilation? Or what is your recommendation on treating this crawlspace area? The exterior walls of this crawlspace are insulated with 1.5" bead board on teh walls, and above grade it is 3" of bead board insulation. Looking for advice?
 
Answer: In a primarily heating environment like MN, extending the ground cover/vapor barrier up the crawl walls and sealing it to the rim joist/underside of the floor as you plan is the correct choice. Permanently sealing the foundation vents is also the correct call. The intent is to bring the crawl space inside the building envelope. There is huge amount of information on this topic available free at buildingscience.com should you wish further confirmation or detail.

Crawl space exhaust venting, while it probably isn’t necessary unless you are concerned with radon or some other untreatable ground source pollutant or if you want backup/redundancy in case the ground cover air/vapor seal fails, will do no harm beyond slightly increasing the building heat load to condition the exhausted air and adding maintenance & fan electrical use costs. As for sizing the fan and determining its CFM setting, I would suggest that the smallest fan running 100% of the time and set at the lowest CFM that would create a very slight depressurization, say one PA or less, in the crawl when the space is completely closed up should be sufficient.
 
-Tony Gill
 

From: Aaron Cate
Subject: Rules and Guidance
 
Question: I have question concerning ASHRAE 62.2.2010. Option 1 says specify that each bathroom recieves 50 cfm intermittent or 20 cfm continuous and kitchen to recieve 100 cfm of intermittent exhaust.. If i can achieve the continuous ventilation needed by just doing the bathroom fan does this mean I still have to install the kitchen exhaust. I need some clarification on this.
 
Answer: The ASHRAE 62.2-2010 Standard requires 1) local ventilation in bathrooms AND kitchens, and 2) whole-building ventilation. However, if you choose to use the alternative compliance approach (Appendix A of the Standard) for existing homes, you may reduce or even eliminate the requirement for local ventilation, but you must increase the whole-building ventilation rate to compensate for the deficiency in local ventilation.
 
Let’s look at two examples, the first meeting the minimum requirements of the Standards without using the alternative compliance approach. First, you must verify that an existing fan (or a new fan you install) is providing 50 CFM on-demand (or 20 CFM continuous) in the bathroom (if there are multiple bathrooms, you must provide this in each). Second, you must verify that an existing fan (or a new fan you install) is providing 100 CFM on-demand in the kitchen. Finally, you must size the whole-building fan and install it. The whole-building fan size is dependent on the square footage of the dwelling and the number of bedrooms; let’s assume this is required to be 30 CFM for continuous operation.
 
For the second example, we will use the alternative compliance approach. Let us assume that the house has an existing 20 CFM fan in the bathroom and that it has no fan in the kitchen. You decide that it will be too expensive to upgrade the bathroom fan and install a kitchen fan. Using the alternative compliance approach, there is a 30 CFM deficit in the bathroom (50 CFM required, but only have 20 CFM) and a 100 CFM deficit in the kitchen (100 CFM required, but have zero CFM). Each of these deficits can be reduced by 20 CFM if there is an openable window in the bathroom and kitchen; let’s assume there is. So we have a final deficit of 10 CFM in the bathroom and 80 CFM in the kitchen. The Standard requires us to sum the deficits (90 CFM) and divide them by 4, for a result of 23 CFM. This 23 CFM must be added to the required whole-building ventilation rate to compensate for the deficits in the local ventilation. So, based on the first example, we would add 23 CFM to the required 30 CMF for whole-building ventilation, a result of 53 CFM.
 
Each of these examples complies with the minimum requirements of the Standard, but the first does not use the alternative compliance approach. It is likely that the first example will provide better indoor air quality, but the second would be significantly less expensive to install.
 
For more detailed information, take a look at the ASHRAE 62.2-2010 Standard, especially Appendix A.
 
-Rick Karg

 
From: Amy Hollander
Category: Health and Safety
Subject: PPE necessary for exterior wall insulation
 
Question: Does the RRP personal protective equipment rule and training require full protection when blowing outdoor sidewalls? I have a film on sidewall insulation but it is quite dusty and the guy is wearing a dust mask instead of a respirator. Is this the rule?: if you are going to disturb more than 20 sq. ft. of outdoor siding, you have to wear a respirator.
 
Answer: According to EPA RRP Rules if you are disturbing an exterior surface greater than 20 feet on a pre-1978 house that has been tested positive for lead (or presumed to have lead), the minimum recommended respirator protection is a disposal P-100 respirator. A dust mask would not provide adequate protection.
 
-Mike Vogel
 

Subject: ASHRAE 62.2
 
Question: I would like to install a small hrv in a modular home, actually thiry modular homes. I don't have a lot of space, need a small unit, 20 to 40 cfm. currently looking at the Zehnder. Please advise on products.
 
Answer: The first place to look for HRV/ERV performance is the HVI Certified Product Directory which has the performance information on all of the certified products. I find the directory tough to search because there’s a lot of information there, but it is the best reference.

The second point is to look at the Gross Airflow and Net Supply Airflow ratings. The Gross Airflow ratings include the cross flow leakage and should be used for duct design. The Net Supply airflow subtracts the measured cross-leakage and is the actual amount of outdoor air delivered by the supply system of the unit and should be used for meeting the required ventilation rate.

And make sure you are comparing the same efficiency numbers. The directory defines these things well:

Apparent Sensible Effectiveness (ASEF): The measured temperature rise of the supply airstream divided by the difference between the outdoor temperature (point 1) and entering exhaust system air
temperature (point 3), then multiplied by the ratio of mass flow rate of the supply airflow divided by the mass flow rate of the lower of the supply or exhaust system airflows. Apparent Sensible Effectiveness is useful to predict final delivered air temperature at a given flow rate and should be used for energy modeling when wattage for air movement is separately accounted for in the energy model.

Sensible Recovery Efficiency (SRE): The net sensible energy recovered by the supply airstream as adjusted by electric consumption, case heat loss or heat gain, air leakage, airflow mass imbalance
between the two airstreams and the energy used for defrost (when running the Very Low Temperature Test), as a percent of the potential sensible energy that could be recovered plus the exhaust fan energy. This value is used to predict and compare Heating Season Performance of the HRV/ERV unit.

Total Recovery Efficiency (TRE): The net total energy (sensible plus latent, also called enthalpy) recovered by the supply airstream adjusted by electric consumption, case heat loss or heat gain, air
leakage and airflow mass imbalance between the two airstreams, as a percent of the potential total energy that could be recovered plus the exhaust fan energy. This value is used to predict and compare
Cooling Season Performance for the HRV/ERV unit.

This table includes a handful of the smaller systems. Some of them have ECM motors that can be speed controlled, but these are their HVI performance numbers. Zehnder, for example, does have a smaller system, but it is not listed in the directory.
 

Brand

Model

Net Airflow in cfm

Sensible Recovery Efficiency

0.1 iwg

0.3 iwg

0.5 iwg

Fantech

SH704

96

67

42

57% @55 cfm

Field Controls

FC95HRV

69

64

55

75% @60 cfm

Goodman

HRV70D

84

64

44

61% @52 cfm

Powrmatic

PHRV96

96

67

42

57% @55 cfm

Venmar

Kubix 44100

82

73

66

55% @36 cfm

Zehnder

Novus 300

205

202

193

91% @64 cfm


-Paul H. Raymer

From: Al Gleason
Category: Health & Safety
Subject: CAZ depressurization
 
Question: WAP Notice 11-6, references combustion appliance zone depressurization testing for Solid Fuel Heating when conducting a required chimney and flue inspection, pre weatherization. What is the CAZ depressurization Pascal limit for atmospheric wood stoves?
 
Answer: Because there is wide variation in the design of solid-fuel appliances, this is a challenging question. For example, an “air-tight” wood stove is likely to be more resistant to surrounding negative pressure than a non-air-tight stove. Additionally, there is much variation of draft strength within the normal operating range of a given appliance. For example, the draft of a wood stove is stronger 30 minutes after loading it at night than it is eight hours later, just before its morning loading.

I think a reliable resource for wood stove depressurization limits is the Minnesota Energy Code 7672.0900, 2005 edition. This Code states that the “maximum depressurization” for “closed controlled combustion wood-burning appliances” is -7 pascals (-0.028-inch water column). The same table lists “decorative wood-burning appliances” as -5 pascals (-0.02-inch water column). Unfortunately, these two types of wood appliance are not defined by the Code. The Minnesota Code makes it clear that if a “manufactured-certified negative tolerance rating” is available, it should be used instead of the above limits.

This information indicates that these wood-burning appliances are more resistant to depressurization than Category I, natural-draft, gas-fired water heaters (-2 pascals) and have about the same resistance as natural-draft oil- and gas-fired furnaces and boilers (-5 pascals). Because of the inherent variability of wood stove design and operation, I suggest using care when doing combustion safety testing for these appliances. Additionally, a working carbon monoxide alarm installed in the room in which the stove is located is very important. Solid fuel appliances ALWAYS produce carbon monoxide; if a stove is spilling, carbon monoxide is entering the house air.
 
-Rick Karg

From: Amanda Clyne
Category: Health & Safety
Subject: Mobile homes and condening furnaces
 
Question: What is the proper way of disposing the condensate from the furnace if there is no drywell or ground drainage system available for a mobile home? Also, how do you stop the condensate line from freezing under the mobile home belly? Note skirting is present.
 
Answer 1: I would run it into a washer or other drain in the home (you could probably run the line in the belly over to the other drain, that way it would be out of the way and still not freeze) or make a French drain under the home, trench and pea gravel, run a steep drain and larger diameter pipe with some insulation.
 
-Joe Hall
 
 
-Stacey Keys

From: Dave Masse
Category: Health and Safety
Subject: ASHRAE 62.2
 
Question: I am currently looking into whole house ventilation to meet ASHRAE 62.2-2010. Are there any Ceiling Mount HRVs? I see Panasonic makes a Ceiling Mount ERV the FV-04VE1. I am looking for a similar unit that is a HRV. The big attic/closet/under floor mount HRVs are too complex and time consuming to install and then periodically service the filter. A nice ceiling mount HRV to provide balanced ventilation would be great, but I can't find any. Also, do you know of any wall mount ventilation fans that are one sone or less? I see the Panasonic FV-08QW1 at 1.1 sone. Close but not good enough. As far as I can tell the only good choices for meeting 62.2 are ceiling mount exhaust fans or attic mount inline exhaust/supply fans? Your response to my questions will be greatly appreciated. Thank you in advance for your time and expert advise.
 
Answer 1: I know of no ceiling mount HRVs and I know of no 1 sone or less wall-mount. I have viewed the 1.1 sone wall mount as meeting the “to the extent possible” part of the WAP requirement.
 
-Paul W. Francisco
 
Answer 2: I don’t know of any single point HRV that are readily available. Although it is difficult to get a handle on all of the different models that all the different manufacturers are making. I do think that Mr. Masse needs to recognize that any HRV or ERV needs regular service and filter cleaning.
 
You might consider running a duct down from the bathroom to an in-line fan or an externally mounted in-line fan like the Fantech RVF4 or RVF6. Because it is a remote mounted fan, it is exempt from the sound requirement (as long as he has 6 feet of ducting). (Although I think the RVF6 is fairly noisy.) But going down and out is often one of the best options.
 
-Paul Raymer

From: Mark Crabtree
Category: Health and Safety
Subject: ACH & Combustion Air
 
Question:I have a unique issue. I have a home with 1,102 sq.ft., 8,816cu.ft., with two exhaust fans that measure out at over 150cfm each. These are not continuous flow fans. I do not have ACH in the home, but at the same time, I do not have enough combustion air for two appliances at 102,000 btu's. These are located in a small open room with a clothes dryer, which is creating a roll out problem on the water heater. WHAT DO I DO???
 
Answer: The problem you describe is not unusual and it can be hazardous. Flame rollout from a combustion appliance can create carbon monoxide in the living area and can damage the controls on the appliance, leading to malfunction. As you have found, the dwelling has too much negative pressure when the fans and the dryer are operating.
 
There are a number of options for solving this problem. I will begin with the least expensive and move on from there. First, you can add enough make-up air to comply with the mechanical code used in your area and to relieve the excessive negative pressure in the space. You can use a passive make-up air system – the least expense – or a mechanical make-up air system that supplies air to the house when the water heater is operating.
 
Second, you can downsize or eliminate one or both of the 150 CFM exhaust fans. You don’t indicate what the uses of these fans are, so I can’t comment on that, but if their function allows, downsize or eliminate one or both.
 
Finally, you can change out the water heater to another type that is more resistant to backdrafting and rollout. I suggest a Category III, forced-draft unit that vents through the wall. This water heater type, with a positive pressure in the vent connector, has the ability to withstand three to four times the negative pressure in the dwelling as a standard Category I, natural-draft unit.
 
You have done your client a great service by discovering this hazardous problem.

-Rick Karg
 

From: Randall Olsen
Category: Monitoring
Subject: Mobile Home Rodent Barriers
 
Question: Is a rodent barrier/underbelly required on a mobile home? If the rodent barrier is very damaged, can it be removed, the floor insulated with batts, twined and no rodent barrier installed?
 
Answer: We used to do something similar to this in the old days, first off, it’s very labor intensive and, shall we say, not so pleasant of a job. It also leaks quite a bit of air and leaves lots of holes for varmints to enter the belly cavity. It would be easier and more efficient if the belly was a flat or longitudinal floor system, but if it’s a hanging belly or crosswise floor system, then I would say there is a better way.
 
We use tyvek or other house wrap material and staple and/or nail it to the wings, then we use about a 9 foot wide piece cut as long as the trailer and thread it through the supports under the duct system, in the middle of the trailer. We then spread it out and secure it to the floor joists next to the I beam. We then blow the belly in the normal way from the side. It sounds harder than it is. It’s actually much easier than insulating the belly using batts.
 
-Cal Steiner
 

From: Mark Kapner
Category: Technical Tools
Subject: Gas Furnace Tune-Up
 
Question: What is the expected improvement (in steady state furnace efficiency) for a residential gas furnace tune-up, following your guideline ? What is the baseline furnace efficiency and the efficiency after the tune-up ?
 
Answer 1: A furnace tune-up, often referred to as a clean and tune, is typically done in WAP as part of the overall furnace inspection. Quite often the systems have not received regular maintenance and have soot build up. The furnace is cleaned, combustion analysis testing is done for CO levels, stack temperature, O2 levels, etc., and then tuned to the maximum efficiency that can be reached. The expected improvement is that the SSE will be at or close to the original SSE for the unit, for instance, an 80% SSE unit will test at 80% or close to it, and a newer 90+ high efficiency unit will test at the manufacturer’s suggested level after the tune up. It is more difficult to answer when the unit is very old and the rated SSE is unknown. I think many HVAC technicians base the desired and realistically expected SSE on their experience with similar units, maybe with an expected SSE of 72 or 76 on older units, and maybe even lower on very old units. The units with lower SSE’s may be candidates for replacement based on potential energy efficiency savings.
-Bob Scott

From: Bill Beachy
Category: Health and Safety
Subject: ASHRAE 62.2 and Multifamily
 
Question: Should ventilation fans in a multi-family building be set the same for all units on all floors, especially if the CFM readings differ from the lower and upper floors?
 
Answer 1: First, I am going to assume that this question has to do with whole-building ventilation, rather than local ventilation intended to exhaust moisture from bathing activities from bathrooms and cooking related pollution from kitchens. For multifamily buildings, the ASHRAE 62.2 committee has defined the word “building” in the term “whole-building” to mean “single dwelling unit”.
 
For whole-building ventilation, ASHRAE 62.2-2010 does not specify that ventilation rates should be set at the same flow rate for each unit in a multifamily building, nor does it specify a method of determining this ventilation rate, other than the procedure used for a single-family buildings.
 
Because the ASHRAE standard is silent on this issue, I will express my opinion. It is important to understand that my opinion does not necessarily express the sentiment of the ASHRAE 62.2 committee nor the DOE low-income weatherization program’s policy regarding ASHRAE 62.2-2010. OK, here goes: Because it is difficult in multifamily buildings to be certain whether “infiltration” as measured by the blower door is from outdoors or from other apartment units; size the ventilation flow rates assuming no infiltration credit, based on the square footage and number of bedrooms. Note that the ASHRAE 62.2 committee has passed an addendum that will be part of the 2013 edition that specifies exactly this, so this position can be considered the view of the committee members, even if this addendum is not a part of the version of the standard required by DOE.
 
Rick Karg with the wise and kind help of Paul Francisco
ASHRAE 62.2 committee members

Answer 2: About the only thing I could add is that if they made an honest attempt and could not find an appropriate sone fan, install the next best fan. I would then get a waiver from the state and document all the searches and info that went into the decision to go with a lesser fan.
 
I have not had the time to research this properly however, so I’m relying on their info that a low sone fan cannot be found for mobiles. I would, if I were the state, receiving the request for the waiver, ask if they contacted several fan companies for advice.
 
- Cal Steiner

From: Dan Auer
Category: Technical Tools
Subject: Bath Fan Controls
 
Question: I am looking for a fan control that will have the fan run a few minutes every hour. I have installed the airetrack and am now hearing of a smart switch. Do you know this product or alternates, please advise.
 
Answer: I’m not aware of a specific “smart switch” but there are several out there that are programmable both for fan speed and cycled run time. Most have an override to boost to full speed when desired. The EFI website catalogue is a good source for what’s generally available. Try http://www.energyfederation.org/consumer/default.php/cPath/39_766.
 
-Tony Gill
 

From: Henry DeWerth
Category: Technical Tools
Subject: Balanced Return Air Pathway
 
Question: If an agency bid proposal included a line item that simply stated "install jump duct in all bedrooms" - in this scenario the supply ducts are in conditioned space and the Building Code terminology is "transfer ducts" would it not be considered prudent to install RAp devices in the partition walls to keep the return air in conditioned space versus running flex duct runs in an unconditioned attic to a common ceiling grill. We are in a hot humid Florida climate and the attic temps can be 140° at times. We think that keeping the return air ducts in conditioned space would yield higher efficient installation and reduce the loads on the heat pump. Would this be true? Would this method be preferred by DOE on a heat pump change out? It would also cost less to implement.
 
Answer: A jump, jumper, or transfer duct serves the function of 1) allowing a free return-air pathway so that the space conditioning system can do a more effective job of conditioning and 2) minimizing pressure imbalances in rooms with closed doors during air handler operation. In some cases, doors can be undercut rather than installing transfer ducts. Clearly in the case here, transfer (jump) ducts are being specified rather than undercutting doors; this is preferred to undercutting.
 
It is always best if ducts can be kept within the thermal/pressure envelope of the dwelling. This minimizes heat transfer to and from conditioned air in the ducts and is likely to make any duct leakage less of an energy drain. So it would be more efficient in Florida to install transfer ducts in interior walls rather than through the hot attic. This will reduce the heat pump loads – summer AND winter – and save energy. Another advantage to keeping ductwork out of the attic is the elimination of the possibility of condensation on the outside of the ducts during cooling season.
 
Because transfer ducts are often installed to serve bedrooms, it is important be aware of the movement of sound. If a transfer duct consists of two grilles across from one another in a partition wall, sound will move freely through this direct “hole”. A better method is to vertically offset the grilles on either side of the partition wall stud bay by three feet or more.
 
Although I don’t speak directly for DOE, I think it is safe to assume DOE would agree with Henry’s ideas for transfer ducts.
 
-Rick Karg
 

From: Dean Cibotti
Category: Training
Subject: Strapping a cathedral ceiling
 
Question: I am wondering if strapping affects the insulative values of insulation? The drywall contractors want to strap, but I am not sure have a 1/2 barrier before the kraft face is a good idea.
 
Answer: Drywall contractors and many builders prefer to strap ceilings before installing drywall because strapping evens out any irregularities in the joists. For example, if one joist bottom is a half-inch higher than the two adjacent ones, the strapping will eliminate the problem, especially if wood shims are used ensure straight strapping and an even drywall plane. However, this practice does add a ¾-inch to ½-inch air space between the bottom of the insulation facing and the top of the drywall. As it turns out, this space can be beneficial to the R-value if the space has no air flowing through it.
 
The additional R-value created by the air space is approximately 0.75 with the kraft paper facing. On the other hand, if the fiberglass were foil faced, the added R-value from the air space would be approximately 2.0. The additional R-value from the foil facing can be attributed to the radiant component of heat transfer. That is, the foil reflects infrared energy much more readily than the non-reflective kraft paper. So not only is the strapping a good technique for ensuring a more even ceiling plane, but it can enhance the ceiling R-value.
 
A warning is appropriate for this strapping detail: It is important to ensure that the air space created by the ceiling strapping is sealed so that air cannot flow through it and thereby eliminate, or more than offset, any R-value gained.
 
-- Rick Karg

From: Andy Caler
Category: Technical Tools
Subject: ASHRAE 62.2-2010
 
Question: This question was brought to my attention by one of our agencies here in Colorado. The issue is with how, in the Ventilation section of 11-6, it states "Implementing ASHRAE 62.2 is not required where acceptable indoor air quality already exists as defined by ASHRAE 62.2.” ASHRAE defines "acceptable indoor air quality" as; air toward which a substantial majority of occupants express dissatisfaction with respect to odor and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk. Is this as straightforward as it sounds? Are auditors required to determine if a house currently has "indoor air quality" issues? If no indoor air quality issues are detected, installing ventilation is not required? Thanks
 
Answer: Let’s begin by quoting the Ventilation action required by DOE Weatherization Program Notice (WPN) 11-6, January 12, 2011: “2010 (or most current) ASHRAE 62.2 is required to be met to the fullest extent possible, when performing weatherization activity. Implementing ASHRAE 62.2 is not required where acceptable indoor air quality already exists as defined by ASHRAE 62.2. Existing fans and blower systems should be updated if not adequate.”
 
ASHRAE 62.2-2010 defines acceptable indoor air quality (IAQ) as: “air toward which a substantial majority of occupants express no dissatisfaction with respect to odor and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk. (page 3)
 
Determining unacceptable indoor air quality can occasionally be quite simple, but it is usually challenging. If the air in a house is reeking of cat urine, it is unacceptable. We all know this; it’s simple. If the water heater is spilling, causing 200 ppm of carbon monoxide to enter the home, it is unacceptable. If a waste pipe has broken in the basement, it is unacceptable. High polluting events are usually pretty easy to detect (not in the case of carbon monoxide or radon) and fix. Our health and safety protocols are set up to find and correct such issues. ASHRAE 62.2 is not intended to address these high-polluting events.
 
The challenges are the more typical cases that might include mold and mildew, formaldehyde emitted from kitchen cabinets, or volatile organic compounds (VOCs) from carpets, paint, and household cleaners. Weatherization personnel do not have the equipment or protocols to detect these problems. ASHRAE 62.2 is intended to mitigate these types of pollution by diluting the household air with fresh outdoor air (whole-building ventilation) and eliminating some pollution at its source (local bathroom and kitchen ventilation). We expect DOE was aware of this when policy makers adopted the use of 62.2 for Weatherization.
 
Both the definition of acceptable IAQ in ASHRAE 62.2 and the full WPN 11-6 acknowledge that there are many contaminants beyond mold and mildew, formaldehyde, and VOCs that might be of concern. These include, but may not be limited to, radon, carbon monoxide, and carbon dioxide. The Ventilation statement in the WPN 11-6 allows agencies to avoid the prescriptive requirement of installing a fan if they can demonstrate acceptable IAQ on a performance basis. However, it is our interpretation that this demonstration is not fulfilled by a subjective assessment by an auditor. Rather, it must be an objective assessment that holds up to questioning. Essentially, if you don’t want to install a fan, prove why it is not needed. Otherwise, don’t try to subjectively assess whether each home meets the definition of acceptable IAQ, but instead implement the prescriptive 62.2 ventilation.
 
Interviews with the client should not be used to assess whether a home has acceptable indoor air quality. One reason is that expressed dissatisfaction is only a part of the definition of acceptable IAQ, and there are pollutants that clients cannot sense which are likely to increase in concentration following weatherization if ventilation is not added. A second reason is that the responses from clients will be based on pre-weatherization, rather than post-weatherization, conditions.
 
The Wisconsin Weatherization Program has been using ASHRAE 62.2 since 2004 and as a result has installed thousands of ventilation systems in low-income homes. Their auditors use the appropriate ASHRAE 62.2 calculations for every job to determine whether to install ventilation, rather than making a subjective determination about indoor air quality. This is the safe way to proceed, at least until a sure-fire and inexpensive method of determining indoor air quality is found.
 
-Rick Karg, with the generous and expert help of Paul Francisco. Both are members of the ASHRAE 62.2 committee.


From: Randall Olsen
Category: Monitoring
Subject: Kneewall Insulation
 
Question: We have long required all kneewall insulation to be covered with a housewrap (Tyvek, etc.). We believe this has to do with possible wind washing reducing the thermal performance of the insullation batt (non human contact area). We request your expert opinion and thoughts on installing housewrap over kneewall insulation. Thank you!
 
Answer: Yes it is always a good idea to cover insulation in a manner that air movement cannot degrade the R-Value, it also helps keep pests out of the insulation. Covering it with house wrap will work. We use John Mannsville comfort therm R-19 or R-13. It is a poly-encased fiberglass batt. We choose to do that as it saves us the labor of installing the house wrap. However, your method is absolutely acceptable.
 
-Cal Steiner

From: Kevin Simonson
Category: Technical Tools
Subject: Core Sampling of Sidewall Insulation
 
Question: We are supposed to take core samples to verify density of sidewall insulation. What is the weight of the sample supposed to be? What tools are needed? Is there an industry standard for core sampling? We are supposed to have 3.4 lbs. per cubic foot.
 
Answer: The important reasons to dense pack insulation are to reduce air leakage through the cavity and to prevent settling. Core sampling can verify the proper density was installed and it can serve as a great training tool.
I have probably done from 200 to 300 core samples on walls where cellulose was blown. I have found it to be a great technique, but it has limitations. Core sampling will give a reliable value for insulation density, but only where the sample is taken; this is important to keep in mind. The core sample at 3 feet above the floor might be 3.5 pounds/ft3, but at 7 feet above there might be little or no insulation.
 
The density of cellulose insulation determined by the core sampling should be from 3.25 to 4.5 pounds/ft3; from 3.5 to 4 pounds/ft3 is just right. If you are measuring another type of insulation, the ideal density will be different. Blown fiberglass, for example, should have a density of 2 pounds/ft3 or more.
 
Unfortunately, a core sampling kit must be pieced together; I don’t know of any commercially available kits you can purchase. You can find the parts required for a core sampling kit on my website at http://www.karg.com/pdf/Insulaton_density/Core_Sample_Kit_document.pdf. Instructions for the use of the kit are included. The “core” I have always used is 2-inch diameter Drain, Waste, and Vent (DWS) copper tubing, 12 inches long. Others use different cores or tubes for extracting the insulation sample. Whatever you use for the core, it is important that your density equivalency table be based on the exact inside diameter of the core. For the core I use, you can find the density table at http://www.karg.com/pdf/Insulaton_density/Core_sample_chart.pdf. This chart is ONLY for cellulose, not for fiberglass.
 
I am not aware of an industry standard for core sampling installed insulation. A few quality control experts have told me that in order to get a reliable idea of whether the walls of a house are adequately dense packed, we would have to take about 30 core samples. Of course, for day-to-day weatherization operations, this is not possible.
 
Don’t ever take a core sample at or within 2 feet of the fill hole where the insulation was blown in. What matters is the density further away from the fill hole; the density 3 to 6 feet from the fill hole demonstrates the skill of the installers and the quality of their equipment.
 
There are a few other methods for checking density that are easier than core sampling, but not as precise. Because I have never checked the density of blown fiberglass, I am limiting my suggestions to cellulose. First, the finger – or digit – method. Drill a hole in the exterior wall sheathing to expose the blown cellulose. If your index finger is able to penetrate the blown cellulose, it is not adequately packed (probably less than 3.5 pounds/ft3). This doesn’t give you a density value, but it is quick.
 
Another simple method was devised by Andy Cordova in Colorado; it’s ingenious. I call it the “twisty thing.” This simple tool is a piece of heavy wire (heavier than a coat hanger; similar to the gauge of the wire used to hold up fiberglass batts under floors), 15 inches long. At one end, put a bend at a right angle to create a 3-inch long leg. Do the same at the other end, but put the 3-inch leg in the opposite direction. After the bending is complete, you have a 3-inch leg at each end pointing in opposite directions, with a 9-inch straight piece connecting the two legs. The shape is like the letter “Z”, but the angles are 90 degrees. To see a picture, please click here. To get an idea of the density of cellulose insulation, drill a ¼-inch hole in the wall, inside or out. Insert the twisty thing half way into the hole. Now try to spin it with the exposed leg. If you are not able to rotate it, the cellulose is dense packed. If you can spin it, it is not dense packed. Elegant and simple.
 
-Rick Karg

From: Joanne Gregory
Category: Technical Tools
Subject: Blower Door Testing
 
Question: Should auditors conduct Blower Door tests in homes where asbestos is present? If so, will it disturb asbestos fibers where they could then become airborne and pose a health risk to auditors and clients? Please advise ASAP. Is there a policy on this topic?
 
Answer: DOE Weatherization Program Notice 11-6 regarding Updated Health and Safety Guidance has some information about asbestos including the following:
 
Asbestos - in vermiculite When vermiculite is present, unless testing determines otherwise, take precautionary measures as if it contains asbestos, such as not using blower door tests and utilizing personal air monitoring while in attics. Where blower door tests are performed, it is a best practice to perform pressurization instead of depressurization. Encapsulation by an appropriately trained asbestos control professional is allowed. Removal is not allowed.
 
The State of Montana did an extensive study on asbestos related to WAP activities that you may be interested in - http://www.ncat.org/special/reach.php
 
-Bob Scott
 

From: Tom Vita
Category: Technical Tools
Subject: Exterior Wall Blows
 
Question: How can you pull aluminum siding off to do a wall blow--without damaging the siding?
 
Answer 1: Removing aluminum siding without damaging it is a challenge. I have seen some technicians in the field make a mess of it and others consistently remove it without damage. As you probably know already, if you dent or crimp it, you can’t hide it.
 
No matter what the siding type, it is a good idea to start the removal process on the back of the house or in another inconspicuous spot. This allows you to get a “feel” for how it is going to come off without damaging an area that will remind the homeowner of you every time they enter the front door.
 
If you can find a person at another agency or a contractor that has a good removal technique, ask if you can help them out for a day or a half day. This is not knowledge you can learn from a book or in a classroom; you must be there to watch and try it for yourself to get the hang of it.
 
By the way, some technicians cut the siding just under the bottom-of-the-clapboard protrusion with a vibrating cutter like the Fein MultiMaster oscillating tool. This makes a clean, narrow cut that is then caulked after the siding is face nailed in place. Don’t assume this is an acceptable method until checking with the appropriate people within your organization. Surely careful removal and replacement is the preferred method.

-Rick Karg
 
Answer 2: I’m with Rick on this one up to finding someone who can successfully remove/replace aluminum siding. I’ve seen the results from a number of people who claimed they could and have to say, none of them could; there was always observable damage to one degree or another. If there is a capable person available – perhaps a really good CAA crew person or someone in the siding trade, it might be possible to create a demonstration video or move them around to do trainings, otherwise, I would advocate for sticking with undercutting the lip as Rick describes below.
 
-Tony Gill
 
Answer 3: The word I get from the real “experts” in the field is this:
a. When you remove it. Take your time, be careful
b. Remove the Styrofoam from the back of the siding before you put it back
c. When you put it back take your time again.
d. Use some soap on the edge so it snaps back on a little easier.
One other suggestion was, have the same person put it on that took it off, then they will be more careful. Other than that, experience goes a long way.

-Cal Steiner

From: Margaret Donnelly
Category: Health and Safety
Subject: Heater Enclosures

Question: In a single family home, atmospheric draft water heater in hallway (adequate room volume). Direct vent natural gas heater in living room (no ducts). dryer in hall way. Does the water heater need to be enclosed?
 
Answer: Per national code, if it isn’t in a bathroom or a bedroom: no. (local code may be more restrictive) The real issue is, does the water heater draft properly under all conditions? To test, put the house in winter-time conditions, turn on all exhaust appliances – including the drier – open and close interior doors and – measuring from the area containing the water heater to the exterior with a manometer - record the lowest depressurization achieved. That’s the worst case depressurization. Check that number against the applicable state technical manual depressurization limit for naturally vented gas water heaters and act accordingly. (accordingly: if the greatest depressurization > than the limit, provide make–up air or replace water heater with a sealed combustion unit; if depressurization < than limit, verify that the water heater drafts properly by firing it under the most adverse condition and checking with a draft gauge or chemical smoke at the draft hood.) Client education and a good CO detector are mandatory!
- Tony Gill

From: Johnny Field
C ategory: Training
Subject: LSW Practices
Question: Our weatherization workers are trained to work as EPA Certified Renovators using the EPA/HUD curriculum. Will these workers also need to attend a class that uses the LSW Minimum Standards Training Curriculum? We also may have some workers on site that have not attended the EPA Renovator training but are supervised by a Certified Renovator. EPA allows these worker to receive on the job training by the Certified Renovator. Does DOE see this as sufficient training or will they need to attend the 8 hour LSW Minimum Standards Training.
 
Answer:
DOE Grant Guidance WPN 10-1 states:
 
Grantees should be advised, Certified Renovator courses are generally created for renovation/remodeling contractors and do not include all aspects of Lead Safe Weatherization (LSW) – the methods and techniques that reduce the spread of dust specific to typical Weatherization activities. Because Certified Renovator courses do not cover all LSW practices, DOE requires ALL Certified Renovators be trained in LSW prior to working on pre-78 housing. Further, since DOE requires LSW in all pre-78 housing, all crew workers must also be trained in LSW before working in pre-78 housing. DOE further requires all Grantee Monitors/Inspectors be Certified Renovators in order to effectively monitor against the EPA requirements AND trained in LSW in order to effectively monitor against LSW minimum requirements.
-Bob Scott
 

 
From: Ryan Harrison
Category: Technical Tools
Subject: Caz test

Question:
Propane water heater with sealed combustion in it's own closet with combustion air from attic, Furnace on roof, gas range. Two bathroom exhaust fans pushing 80cfm each, laundry room exhaust fan 50cfm and range hood 200cfm, with 144cu inch fresh air opening to help bring down caz to -4.2pascals. We are negative -1.2 pascals over limit. Is there any flexibility here. I know negative or positive 3pascals is the limit on caz, but there should be flexibility here based on the type of appliances. Please contact me. Thank you much Ryan.

Answer 1: Ryan, here is my understanding of the scene:
Ryan, here is my understanding of the scene:
 
  • The propane water heater is a direct-vent, sealed combustion appliance.
  • The furnace is on the roof.
  • The gas range is not vented.
  • The bathroom, kitchen, and laundry exhaust fans are depressurizing the house and/or CAZ to -4.2 Pascals with the 144 square inch air vent open.
  • I am not sure whether there is a clothes dryer or not. If there is, it should be operating during your testing.

Based on the details you supplied, I don’t think you have a problem.

  • If the CAZ is the water heater closet, the depressurization limit is not being exceeded because the water heater is direct-vent, sealed combustion. This means that this appliance is safe with the CAZ pressure of -4.2 Pascals.
  • If the CAZ is where the furnace is -- outdoors, there is not a problem because the furnace is on the roof where the house depressurization due to the exhaust fans will not affect it.
  • If the CAZ in the kitchen where the gas range is, there is no problem because the gas range is not vented, so it cannot be back-drafted by the exhaust fans.
Regarding your comment about the flexibility of this analysis; as you know, there are several parts to combustion safety testing. Your question addresses only the CAZ depressurization limits for vented combustion appliances. Other parts of the testing usually include checking for spillage within the first few minutes of startup, checking for adequate draft at steady-state, and measuring carbon monoxide levels at steady-state (when the vent temperature stabilizes).
 
Weatherization programs might have slightly different methods and thresholds values for these test procedures, but all are using fairly similar procedures. Clear failure of one or more of the required tests should always indicate the need for the technician to fix the problems. However, in cases where the combustion safety testing indicates a situation where a combustion appliance barely fails or barely passes, it is up to the technician to decide whether allow it to pass or report it as failed. This is where the flexibility is; in the experienced judgment of the technician. We owe it to our clients and customers to always be cautious with our judgments and to keep their safety as our primary concern.
 
-Rick Karg
Answer 2: Ryan is correct. There should be – and is – CAZ test flexibility depending on the type of appliance. CAZ test requirements don’t apply to a sealed combustion appliance. The point of sealed combustion is the combustion appliance gets its combustion air directly from the outside and also exhausts its byproducts directly to the outside. It’s uncoupled from the home’s interior and therefore not affected in any way by either pressure in or depressurization of the space it occupies.
- Tony Gill

 
From: Thomas Billups
Category: Technical Tools
Subject: Vapor Barrier Adhesive

Question: Does anyone have a product that works well on sealing plastic vapor barriers to masonry? Georgia agencies have used mastic and different tube caulks and sealants with little success. The product that's worked best for our agencies is PL Premium construction adhesive, but like most adhesives it doesn't stick to cold surfaces. Since most of the U.S. Wx network is in colder climates than Georgia's, there's got to be something out there that will work for us year round. Any suggestions?
 
Answer 1: Historically Maine generally used either one or two part foam to glue the edge of poly ground covers to concrete or cement block. It seemed to hold up pretty well.
 
-Tony Gill
 

Answer 2: I would try a one part urethane sealant such as NP-1, we use it in the winter on mobile home roofs with no problem. It will adhere great, just keep it warm up until the time you use it. Tony’s ideas is also a good one.

 
- Cal Steiner
 

From: Margaret Donnelly
Category: Health and Safety
Subject: Solid Fuel Burning Appliance: Wood Burners
 
Question: In a mobile home, if solid fuel appliance gets combustion air from inside, must we convert to outside air? Not main source of heat. How about site built homes?
 
Answer 1: Common sense answer: Either convert it to sealed combustion, get the client to agree in writing not to use it or remove or permanently disconnect it.
Rule answer: I’m a little weak on this one. I understand that the HUD code (authority behind the MH HUD sticker) requires all MH fossil fuel appliances (except ranges & they have to have a vented range hood) to be sealed combustion.

For weatherizers, wouldn’t the HUD code only apply if the Program addressed the offending heating unit? If not addressing the heating unit wouldn’t the Wx Program requirement be to follow whatever is in the approved local State Plan covering weatherizing – particularly air sealing – a MH with non-sealed combustion units?
 
- Tony Gill
 
Answer 2: If DOE has not released a policy, we must answer this question without DOR guidance. Tony’s answer might be too severe; I am not sure if they must remove it just because it takes its combustion air from the indoors. However, the furnace and the water heater do not take combustion air from the indoors. Using this logic, Tony is correct; we should avoid using combustion appliances that take combustion air from the indoors. Tony’s answer is certainly the safe way to proceed.
 
On the other hand, for a site-build dwelling, this is not the case. A wood stove vented to the outdoors is OK, as long as the weatherization analyst has determined it is venting properly under worst-case conditions.
 
- Rick Karg
 
Answer 3: I am pretty certain that update has not happened. The most descriptive notice about wood stoves is from 1988.
 
I agree with your assessment on mobile homes – as far as I know there is a UL listing for approved mobile home stoves based on getting outside combustion air. And if this is indeed the only/latest guidance, then addressing wood stoves in the State Plan is critical.
 
- Bob Scott
 
Answer 4: I agree with Tony, only with a few clarifications. Rick also has some very valid points that need to be considered.
 
I want no part of an non-sealed combustion appliance/wood stove in the main body of a mobile home, especially after we tighten it up. I have witnessed a water heater back draft in a tight mobile home when the furnace came on, it created only a -2 Pascal’s of pressure caused by several small holes in the duct work. The ductwork passed our minimum pressure pan test with flying colors, but because the home was so tight and the volume smaller than most sight builts, the small pressure did back draft the water heater (which had a connection to the main body of the house due to an error by the utility) and cause CO to enter the structure. This was causing one of the kids to become very ill.
 
The only things I would do on a this mobile home is seal the duct work, and WCDT. Absolutely do nothing that would reduce the infiltration with the exception of sealing the ductwork that would cause depressurization of the unit when the furnace fan is activated.
 
Basically, if the ductwork is not sealed extremely well, we will run the risk of back-drafting any non sealed combustion appliance when the furnace comes on. Not on my watch.

-Cal Steiner

 
From: Claudia Elliott
Category: Health & Safety
Subject: Mobile Home Furnace Tune and Clean
 
Question: How do you obtain the Net Stack Temperature, Flue Gas Temperature, Steady State Efficiency, and the Flue Gases at the top of the heat exchanger on a sealed combustion mobile home furnace. According to the manufacturer, the only way to get these readings is to penetrate through the venting system, which is strongly discouraged by the manufacturer of mobile home furnaces.
 
Answer: It is possible to obtain all the data you wish at the top of the combustion exhaust vent on a sealed combustion mobile home furnace. Just make sure that the samples you take are without any dilution air. Of course, the problem with this method is that it is a hassle and unsafe to get up on the roof.
 
As an alternative, it is possible to drill through the outer (combustion supply air) and inner (combustion gases) layers of the concentric pipes above the furnace. Once you drill the hole, you insert the probe of your combustion analyzer into the inner pipe for your testing. The problem with this method is that you then must plug BOTH holes with a threaded bolt. This can be difficult to do. Some weatherization programs have done this for years; others do not allow it. I suggest you consult with the manufacturer of the furnace before drilling. They might tell your drilling will void the warranty.
 
If you do decide to drill after the manufacturer’s and program manager’s approval, look for an existing bolt first. You might find one you can simply remove and replace rather than drilling a new hole.
 
-Rick Karg

 
From: John Melnick
Category: Public Information
Subject: Improving the energy efficiency of a converted area
 
Question: A garage area about 15 ft x 30 ft is under consideration to be converted into an in-law living area. What (if anything) can be done to improve the energy efficiency of the area? This is located in upstate NY.
 
Answer 1: Because the garage has no sub-floor or basement it would be difficult in the central NY environment to condition the floor area of the garage. The coldest air from the ground would be difficult and expensive to control by floor sealing. The floor is a large area and difficult to improve the energy efficiency enough to maintain heating comfort at a reasonable cost. Replacing the garage car door with a permanent wall and enclosing the ceiling along with adding dense packed insulation to both areas is important. As well as air and draft sealing in areas around the windows, doors, foundation walls and floor cracks will all help greatly too. But the vast amount of the cold air will come through the concrete floor. The one thing that could be considered is barrier sealing. Where a proper barrier material is rolled and sealed on to the floor to reduce the cold air flow. The cost and the correct material, that is plastic vapor barrier and the vapor barrier adhesive (for cold surface masonry application) would need to be determined and proven to be effective before installation.
 
But the floor I see as the biggest part of the solution. And normally garage are not designed to be a permanent occupied area of most houses, and I don't know have any other ideas?

-John Williams
 
Answer 2: I agree with John's assessment that the replacing the garage door with a permanent wall and enclosing the ceiling along with adding dense packed insulation to both areas will be an important step. This floor should also be treated as a slab on grade foundation. With the proper equipment, tools and materials it can be efficiently completed.
 
-Cal Steiner
 
Answer 3: Weatherizing this garage should follow the same principles as used for weatherizing any structure: Reduce surface heat loss and minimize air leakage. We won’t discuss reducing heat gain because this is in New York.
 
As usual, take care of air leakage before insulating to reduce surface heat loss. Most of the air leakage will probably be eliminated by replacing the overhead doors with framed and insulated walls. Pay attention to the details of air sealing when these walls are built and then insulate them to reduce surface heat loss.
 
Make sure the ceiling has a cost-effective level of insulation – probably R-38 to R-50 – and don’t forget to air seal first. Don’t forget to check the integrity of the windows and exterior doors.
For this rehab, the most challenging task will be the slab floor. As a garage, it is unlikely the floor was treated in any way to reduce surface heat loss when it was built. Check for air leakage where the walls meet the slab and seal if needed. For reducing surface heat loss, there are a few options. First, build a floor of 2 x 4s that rests directly on the slab or on rigid extruded polystyrene insulation that covers the slab. If rigid insulation is used, fiberglass can also be put between the 2 x 4 sleeper joists. Of course, use a cost-effective amount of insulation. Finish this new floor as desired.
 
Second, insulate the perimeter of the slab. There is a product called FP Panel, it is one inch blue board with a pea gravel exterior. We use it on situations like this. One would dig down as far as reasonably possible next to the slab and concrete foundation, then attach the FP panel and put on a drip cap on the top of the panel. You would then have a perimeter insulation going from the sill plate down at least a foot into the ground. If you had room, you could also go out 1-2 feet about 6 inches into the soil next to the slab. Inside the room I would also use carpeting with a nice thick pad to help with the insulation.
 
The first option for the slab will reduce heat loss significantly more that the second, but it will also be more expensive. However, I suspect the first will have a greater savings-to-investment ration, especially if you are careful with the cost of your materials.
 
Make the new living space warm and cozy with a direct-vent space heater vented through the wall. Now, cross your fingers and hope your in-law is happy in their new home.
 
-Rick Karg


More discussions about Weatherization and SIRTT can be found on the WAPTAC/SIRTT Message Board.

 



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