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Question DetailsAsked on 3/18/2014

We have air sealed and added addtional insulation in attic but our attic is reading almost same temp as living spac

We have probably put 5k in trying to fix our drafty house. Our house is 11 years old and we have had the attic air sealed and have an r60 up there. The company who did this had to come out again because they did not do it right first time and I know there is still an issue. Attic is almost same temp as living space. We have 1 supply and return duct in there for one bedroom. There is extreme negative pressure in house. Uncondtioned air is always rushing in to house. We have an Extreme dusty house, the house always feels drafty. Chipped wood furrniture, caulking, black marks on door hinges, rusty tools in attached garage. baffles in attic are installed. Basement sils and top plates have been air seal along with rigid foam board. Any suggestions on how to correct? current reading in attic 68 degrees with 25 humidity. living space temp 69 26 humid. I think this is almost a job for a home improvement show. All suggestions welcome. Thanks

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11 Answers

0
Votes

Search for a home performance contractor or a company that just tests home performance. A blower door test will quantify the leakage, and artificial smoke will find the locations.


Also have the duct system tested by www.aeroseal.com or a duct blaster test, finding and sealing the leaks. Supply air duct leaks in wall/floor cavities as well as attic, can make the home go negative, could be the souce of the negative pressure you have.

Source: www.bayareacool.com

Answered 5 years ago by BayAreaAC

0
Votes

When you say attic is same temp as house - I presume you mean th outside air is dramatically different than that temp ?


BayAreaAC put you on the right track - sounds like you sank $5K into insulation without getting an energy audit and blower door test with smoke testing or thermal IR up front - about $500 range typically, including thermal IR. That will show you where the leaks are, and where your worst energy losses occur. I would spend the extra $150 or so over the basic energy audit when you get it done to have the thermal infrared camera run both inside and outside and in attic and on roof - make sure they have a system that is color, and records on DVD or thumbdrive in standard video format, so you and any future contractors can view it in the future on any computer when you are talking improvements to stop air leaks.


Here is a link to a Youtube video from probably the largest manufacturer of thermal IR systems, explaining and showing both the blower door test and thermal IR scanning.

http://www.youtube.com/watch?v=4t1C6T...


I would first have an HVAC contractor check your HVAC system for broken ducts, duct leakage, and suitability of makeup air for furnace and water heater - you may have inadequate makeup air for them, in which case they would be sucking outside air through ceiling and walls and windows, causing drafts.


I think they already did your house - ThisOldHouse had a show on an older farm house that the owners had put over $10,000 insulation into and fuell bill changed less than 10% - they went through where the proboems were, and why insulation itself is pretty useless if you do not first block off the main sources of air infiltration/exfiltration.

Answered 5 years ago by LCD

2
Votes

Go to www.bpi.org and find a BPI qualified energy auditor in your area to perform both blower door and duct leakage testing. BPI certified contractors must meet certain training and energy auditing standards and perform most state/utility approved home energy audits.

Answered 5 years ago by hosey

0
Votes

Often what people think is a draft, is convection. Hot air rises, cold air falls down off the windows and it creates currents. Get the blower door test. If you have less than 2 air changes an hour, you probably need an air to air heat exchanger to get rid of the excess moisture. It is not a good idea to use showers without a ventilating fan in a well insulated house.

Your local utility may do some testing free of charge

Answered 5 years ago by Guest_9604509

0
Votes

Another association to find raters for testing is ;



http://www.resnet.us/

Source: www.bayareacool.com

Answered 5 years ago by BayAreaAC

2
Votes

You need to blower door test the home and verify the results. There typically is test in and test out measurements when you are doing a full scope air sealing and insulation project.


Based on how you have described it, doesn't seem like the insulation and weatherization contractor did a good job.


Bayarea's suggestion of AeroSeal is also great. Hopefully there is some duct leakage via bad seams (not large breaks) that they can get to with that.


FYI...the 2 air change per hour recommendation is incorrect. You need to be looking at 0.35 ACH.

Answered 5 years ago by WoWHomeSolutions

0
Votes

Please.. A buildings airflow is determined by the ASHRE standard. Airflow, or the number of air exchanges per hour in the house is calulated based on the building volume or number of occupants, whichever is greater.. There are additional numbers used as well in the formula. Airflow too low, potential indoor air quality issues, too high, and excessive infiltration/energy costs.

The .35 number referenced is part of the formula used to determine the ASHRE recommended aiflow/air exchanges for that particular home. A competent BPI or Resnet auditor using a blower door pressure of 50p wrt outside will determine based on the ASHRE formula if the conditioned space within the house shell is within the prescribed limits or if measures are needed. Using a specialized manometer, a competent energy auditor will determine any building pressure issues, combustion appliance draft issues and stack effect. A pressure pan connected to the manometer can quickly isolate a duct issue.

Answered 5 years ago by hosey

0
Votes

A note on the Blower Door test - this is a whole-house test which measures your current conditions, and just ah-so may not mean much to you. Unless combined with a couple of other steps, it tells you how airtight your house is and is useful in designing an HVAC system, but not with respect to weatherstripping and insulation.


Two other things that are NOT necessarily part of the "standard" test, but do not cost a great deal to add as part of it:

1) sealing of ALL outside vents (obviously after shutting down all equipment) - furnace and water heater fresh air intakes and flue, fireplaces, bathroom and kitchen vents, etc) with visqueen, and re-running the test so you know how much of the inflow measured is due to "leakage" and how much due to ducts and flues beyond your control. This is also when smoke/IR scanning should be done, so inflow from those "uncontrollable" areas does not cause drafts that affect the information you are getting about "controillable" leaks.


2) doing thermal IR (preferable - more precise) or "smoke" test (harmless "smoke" that generally shows where drafts are) to identify, WHILE blower door is running in depressurize mode, where your most significant air inflows are occurring - whether around ducts, doors, windows, wiring and plumbing penetrations, electrical outlets, or where - and writing down or marking with colored tape so you have a record of which were small, which were large draft contributors. Should be done both inside (including basement) and (in pressurization mode) in the attic, and ideally (though not all blower door fans are reversible) also with positive pressure into the house, which is actually the more realistic test as HVAC systems tend to pressurize, not depressurize houses.


3) then remove sealing on fan and duct openings to outside which have flappers or reverse-flow preventers, while fan is in depressurize mode, to check effectiveness of the backflow preventers.

Answered 5 years ago by LCD

0
Votes

Reread your question - you say you have one supply and one return duct "in there for one bedroom" - I presume you mean in the attic ? And you say attic runs same temp as house, and you get dust and unconditioned air in house. Sounds to me like this may be simpler than I originally thought, and very similar to another case here about a year or so ago - maybe your insulation contractors broke or pulled loose your return air duct - so instead of pulling conditioned air from the bedroom in the attic, it is pulling attic air into your duct system.


Putting a piece of paper over the return air vent in the bedroom will NOT by itself solve this question - because if the return air duct is disconnect but the feed to the bedroom is on, the positive pressure in the bedroom will cause air to flow out the vent to the attic, making it look like the return duct is pulling air. Try the paper trick with a singlethickness of newspaper, but make sure the bedroom window is wide open so there is no pressurization of the area - THEN if the paper wants to suck up tight to the return air vent, unless your entire attic is airtight then your return duct is probably OK. Of course, if you can physically inspect the duct for rips or disconnection (questionable with R60 insulation) so much the better.


You could also try the same thing with all other return vents while the HVAC system is on - maybe some other room has a disconnected or torn duct.

Answered 5 years ago by LCD

1
Vote

Hosey,


We can get more technical if you want but I was trying to illustrate the point that the recommendation of 2 ACH is way off.


Ventilation Requirements

· MVR (minimum ventilation requirement) or also called the BTL (building tightness limit)

o 0.35 air changes per hour but not less than 15 cfm per person (whichever is higher)

§ For calculating the air changes per hour, the volume of the living spaces shall include all areas within the conditioned space. The ventilation is normally satisfied by infiltration and natural ventilation. Dwellings with tight enclosures may require supplemental ventilation supply for fuel-burning appliances, including fireplaces and mechanically exhausted appliances. Occupant loading shall be based on the number of bedrooms as follows: first bedroom, two per- sons; each additional bedroom, one person. Where higher occupant loadings are known, they shall be used.

Answered 5 years ago by WoWHomeSolutions

0
Votes

Not to stir the pot, but what the heck - I think the two different numbers being thrown around here are apples and oranges.


The 0.35 (actually 1/3 in original committee report) ACH (air changes per hour) relates to what the BPI and several other groups consider a "tight" house - for purposes of energy efficiency and reducing HVAC demand, to reduce the risk of CO and CO2 buildup from gas appliances like stoves, and to dilute indoor contaminants and odors.


The 2 ACH (air changes per hour) number comes from the old ASHRAE Air Conditioning Manual from the 1970's (now called the ASHRAE Air Conditioning Design Manual) and as I recall from my old code committe days, some University of Missouri and Corps of Engineers Cold Regions Research and Engineering Labs research done leading up to that, and relates to the point where specific humidity control MAY be necessary, and should be looked into in system design. Less than about 2 ACH, or about 4-5 in very cold climate conditions, tends to result in excess moisture buildup in at least some parts of the structure. These are empirical numbers, not code requirements - I think the only place I have seen them codified is in Corps of Engineers Design Manuals.


Working in a very cold winter area, I have seen far more serious problems with winter heat loss from moisture buildup in insulation in modern and retrofitted "tight" homes than in older leaky ones, because of a failure to account for moisture. It is not in the least uncommon to go into a new (less than 2 year old) subdivision and see ice glaciering on the bottom of windows, water running down the panes, and glistening wetness on bathroom and kitchen walls because of excess humidity. You can say this is due to inadequate moisture removal - I say if a home in normal use does this, it is the fault of the code writers for forcing builders into excessively "tight" homes. Then you see the "solution" - whole house ventilation systems that exchange conditioned air for outside unheated air, totally wasting a lot of the heat you put into the home. It is long past time for deliberate humidity control to be built into HVAC systems INCLUDING A/C evaporators, rather than being added on only in desperate situations, and for heat recovery from exhaust air in homes with whole-house conditioning - just like is done in many larger commercial buildings.

Answered 5 years ago by LCD




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