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  1. #1
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    Dec 2015
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    Austin
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    Confused - Proper way to connect and ERV

    Close to installing an ERV. Found a local HVAC company in Austin that I like, but have doubts the installation of the ERV. They will install the ERV such that stale air will be exhausted from my return air duct and fresh air will be reinserted back into the return air duct but closer to the evaporator.

    That makes sense to me, but this paper recommends against doing that:
    http://www.comfortsolutionsinc.com/d...ty%20Areas.pdf

    Also the suggested unit is a Carrier with a TRE rating of (up to) 52%.
    According to the reference above that seems low.

    Appreciate any input.

    Regards
    Randy

  2. #2
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    Sep 2015
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    I'm not a fan of ERV's for residential applications. Given the High square foot/person and high exterior square foot/person compared to office buildings, homes often have plenty leakage or infiltration for ventilation needs.

    ERVs add maintenance and related cost that typically is conciously forgotten and consequently negates the purchase.

    The only thing that article is good for is wiping your bum.

  3. #3
    Join Date
    Dec 2015
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    Austin
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    Thanks for the input.

    My Condo is sealed with Spray Foam from top to bottom. Extremely unleaky.
    VOCs are elevated ~3x and odors are bad. Fresh air is my only solution.

    Problem is the more I learn the less faith I have in my local contractors.

    I'm open to suggestions. Perhaps I should reconsider forced air with a dehumidifier.
    I was partial to ERV simple because they blow nasty air out and take fresh in. My assumption was that an ERV would be more efficient at pushing the bad stuff out.
    Maybe this assumption is wrong.

  4. #4
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    Sep 2014
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    NW Arkansas
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    If you have the money an erv/hrv is the better way to go for fresh air. Now as for tying into the return only portion.... It might be the only way. Is there an adequate way to run new supplies and returns for the new system? If so do that but know that it costs more.

    As to the contractor, try and use our contractor locator map . A quick scan shows several near Austin. Ask them questions about fresh air systems and see who answeres your questions the best.

    Using a dehumidifier might be required anyways with a highly sealed home. Have a different contractor come out and talk with you about your options.

  5. #5
    Join Date
    Dec 2015
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    Austin
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    Quote Originally Posted by Snaple4 View Post
    If you have the money an erv/hrv is the better way to go for fresh air. Now as for tying into the return only portion.... It might be the only way. Is there an adequate way to run new supplies and returns for the new system? If so do that but know that it costs more.

    As to the contractor, try and use our contractor locator map . A quick scan shows several near Austin. Ask them questions about fresh air systems and see who answeres your questions the best.

    Using a dehumidifier might be required anyways with a highly sealed home. Have a different contractor come out and talk with you about your options.
    Thanks - that concurs with the research I've been finding. I appreciate the confirmation.

    I know a lot of folks like the fresh air intake with dehumidifying.
    I just don't think that will be as good as an ERV for complete air exchanges. With *fresh air intake only* seems like I'll counting on vents and leaks to get complete air exchanges as opposed to directly venting the stale air out directly with an ERV. Also don't like the idea of sucking in hot air.

    Thanks for the link to contractors in my area. Have these guys been vetted?

    A lot of the locals guys I've been talking to can tell a good story, but I learned a long time ago the limitations of a good story.

    Again - Thanks

    Randy

  6. #6
    Join Date
    Jul 2014
    Location
    Apache Junction, Arizona
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    I see alot of times the OSA like the damper or economizer in the field is shut completely down.. allowing zero outside air into the building... a pet peeve of mine....

    if your house is sealed fairly well like you indicate then you may not be getting the outside air you need for your comfort and safety, that is something to consider.

    If your contractor has the equipment like the Honeywell IAQ meter you can swiftly tell if you are getting the correct CO2 level you need and CO limits you dont need...

    also the contractors on this site are very very vetted..

    I had to go through alot of proving who and what I was and where and how I was Licensed and Bonded just to get on this site as a professional.

    I told my partner this site is more strict than the state of Arizona for vetting HVAC Techs and Contractors.

    Good Luck with it.
    "I never lie because I don't fear anyone. You only lie when you're afraid." - John Gotti

    “Always shoot first . . . that way they know you’re armed!” - Orrin Porter Rockwell

    "Individuals and entities performing contracting work illegally and without a license place the public at risk and effectively steal millions from Arizona's hardworking, law-abiding contractors and their employees," - Jeff Fleetham, director of the Arizona Registrar of Contractors.

  7. #7
    Join Date
    Dec 2015
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    Austin
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    Quote Originally Posted by HellGato View Post
    I see alot of times the OSA like the damper or economizer in the field is shut completely down.. allowing zero outside air into the building... a pet peeve of mine....

    if your house is sealed fairly well like you indicate then you may not be getting the outside air you need for your comfort and safety, that is something to consider.

    If your contractor has the equipment like the Honeywell IAQ meter you can swiftly tell if you are getting the correct CO2 level you need and CO limits you dont need...

    also the contractors on this site are very very vetted..

    I had to go through alot of proving who and what I was and where and how I was Licensed and Bonded just to get on this site as a professional.

    I told my partner this site is more strict than the state of Arizona for vetting HVAC Techs and Contractors.

    Good Luck with it.
    Thanks for your input.

    I've had my air tested twice for a complete analysis. VOCs are through the roof. Total VOC levels are 1400ng/Liter. Should be under 400 max. Previous tennants used alot of fragrance chemicals among other things.
    CO2 levels with 1 person are over 1100 after just a few hours.


    As far as I can tell there is not an out door air being brought in. Unit was built in 2008 before code (in my area) required out door ventilation.

    Appreciate your input on how contractors are vetted here before meriting recommendation on the forums. Have already called a few and am very impressed.

    Thanks again
    Randy

  8. #8
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Quote Originally Posted by randyf View Post
    Close to installing an ERV. Found a local HVAC company in Austin that I like, but have doubts the installation of the ERV. They will install the ERV such that stale air will be exhausted from my return air duct and fresh air will be reinserted back into the return air duct but closer to the evaporator.

    That makes sense to me, but this paper recommends against doing that:
    http://www.comfortsolutionsinc.com/d...ty%20Areas.pdf

    Also the suggested unit is a Carrier with a TRE rating of (up to) 52%.
    According to the reference above that seems low.

    Appreciate any input.

    Regards
    Randy
    This could end up being a mess. The type of install you are describing requires operating the a/c blow when fresh air ventilating. Not good, the blow will consume more energy than the ERV will save plus quickly re-evaporate moisture on the cooling coil back to the home. Best to draw stale air from the bath or open part of the home while supplying fresh air to return. This would allow the operation of the ERV independent of the a/c blower. The fresh air should be on when the space is occupied, independent of heating/cooling.
    Also monitor the %RH to not exceed 60%RH. You will need supplemental dehumidification and try to maintain <50%RH. Do not operate the ERV when unoccupied during the damp/very dry times of the year. The 52%RH is about as good as it gets. It is a "forever" payback, but much better than no fresh air.

    Keep us posted.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

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