Page 1 of 3 123 LastLast
Results 1 to 13 of 30
  1. #1
    Join Date
    Oct 2012
    Posts
    87

    New Construction Next Steps: ERV & Dehumidifier -Advice?

    Hi new to the board & was sent here by the gardenweb folks to ask the HVAC pros here for some help. So please dumb it down for me as much as you can.

    We are building a house:
    *~2900 sf
    * 1.5 stories bungalow front/ranch back
    * conditioned crawl space
    * Foam roof lines/ cellulose attic/ closed cell batts for walls
    * Earthcraft certified with blown door tested
    * Gas range - 4 burner with 600 CFM vent hood
    * 12 windows 1st floor - 9 windows upstairs
    * central VA/midatlantic/richmond
    * temps mid 40's winters/ 90's summers/55+ humidity most of the time
    * Nat gas & elect available
    * Hate humidity


    Equipment selected so far through builder/HVAC sub:
    * Trane XR16 Heat Pump (upto 18 SEER/9.5 HSPF/2-stage/3 tons)
    * Chose this after review of our heating needs vs. winter temp expectations in our area

    Question:
    1) Would we need a ERV?
    2) Would we need a Dehumidifier? - seems this is big point here from what I've read - not sure why

    Appreciate any feedback. Thanks!
    Last edited by Ben44; 10-05-2012 at 11:15 AM.

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,674
    If humidity is a concern, which for most it is whether they know it or not, a dehumidifier is a good choice because in low load conditions the ac won't be running therefore you will need suplimental dehumidification. I'm sure teddy bear will be along in a few to elaborate. You can bring in fresh air with a dehumidifier as well to get proper air changes to purge indoor pollutants.

  3. #3
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Definitely look at a whole house dehumidifier. The Trane XL16i (I assume XR 16 is the same unit with a different case) is known ot have poor dehumidificaiton on low stage.

    I would also look at a ERV as well. But I would run the ERV semi-independently so that it constantly exhausts air from bathrooms and the kitchen, and then supplies fresh air to the air handler to be distributed to the house.

    You will then need a independant make-up air unit for that range hood that it intelocked electrically with the exhaust fan. You won't find a 600CFM ERV either. Also keep in mind that when running on a hot day, you'll need almost 2 tons of AC capacity to cool and dehumidify the air it draws in. In winter, you might need that much to heat it.

    I honestly haven't personally descided what hte best way is to handle thsoe large exhaust hoods. It's tricky when you combine commericale style systems in a residential HVAC environment. Commerical HVAC cna be deisgned to have large amounts of make-up air and maintain buildign pressure in varying conditions. You can get small make-up air units to do the same. But in residential, the equipment is used intermittently. SOmetiems i think you'd be best ot go with a commerical air handler or rooftop unit with a economizer, or even better a dedicated 1/2 ton hydronic air handler with a chilled water system set-up as a make-up air unit that would supply air directly back into the kitchen, and possibly have a damper and otherwise serve jsut hte kitchen space.

  4. #4
    Join Date
    Oct 2012
    Posts
    87
    Quote Originally Posted by jtrammel View Post
    If humidity is a concern, which for most it is whether they know it or not, a dehumidifier is a good choice because in low load conditions the ac won't be running therefore you will need suplimental dehumidification. I'm sure teddy bear will be along in a few to elaborate. You can bring in fresh air with a dehumidifier as well to get proper air changes to purge indoor pollutants.

    Thanks J Trammel for chiming in. Can't wait for the Bear to show up LOL! I've read his writings.
    Any how, are you suggesting that a dehumidifier can also serve as an ERV?

    Also, I've done some lite budgeting & it appears that a separate ERV & a whole house DH would run @ least $1K+ each?
    That's a big $2K expense that I rather not broach with the tight budget already of the new build. So seeking alternatives that meets the need would be preferable.

  5. #5
    Join Date
    Oct 2012
    Posts
    87
    Quote Originally Posted by motoguy128 View Post
    Definitely look at a whole house dehumidifier. The Trane XL16i (I assume XR 16 is the same unit with a different case) is known ot have poor dehumidificaiton on low stage.
    Oooh - might have to research on your Trane statement. Do you think in a 'tight' house that humidity would be an issue?

    Quote Originally Posted by motoguy128 View Post
    I would also look at a ERV as well. But I would run the ERV semi-independently so that it constantly exhausts air from bathrooms and the kitchen, and then supplies fresh air to the air handler to be distributed to the house.
    Can a centralize ERV's serve as a replacement for bathroom exhausting? Or would I still need indv. bathroom exhausts?

    Quote Originally Posted by motoguy128 View Post
    You will then need a independant make-up air unit for that range hood that it intelocked electrically with the exhaust fan. You won't find a 600CFM ERV either. Also keep in mind that when running on a hot day, you'll need almost 2 tons of AC capacity to cool and dehumidify the air it draws in. In winter, you might need that much to heat it.

    I honestly haven't personally descided what hte best way is to handle thsoe large exhaust hoods. It's tricky when you combine commericale style systems in a residential HVAC environment. Commerical HVAC cna be deisgned to have large amounts of make-up air and maintain buildign pressure in varying conditions. You can get small make-up air units to do the same. But in residential, the equipment is used intermittently. SOmetiems i think you'd be best ot go with a commerical air handler or rooftop unit with a economizer, or even better a dedicated 1/2 ton hydronic air handler with a chilled water system set-up as a make-up air unit that would supply air directly back into the kitchen, and possibly have a damper and otherwise serve jsut hte kitchen space.
    To tell you the truth, these large hoods are starting to be more costly than their worth with all these 'add-ons'. We are erring on the side of conventional wisdom which says to provide x CFM's (8" duct btw) to cover a 30" 4-burner gas range. Even though we will NEVER have all 4 burners lit up MAX @ any one time.

    We are sensitive to smells, so minimizing the smell is a primary concern but reading has lead us to believe that we will have to add in MUA, Recovery Ventilators, & Dehumidifiers because we essentially are sucking out air & have to introduce air again into the envelope.

    Sorry to whine, I guess we never knew it can be so complicated & costly to breath! LOL!

  6. #6
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Yes, the large hoods can be more trouble than they are worth.

  7. #7
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    The quest for perfect IAQ can be very expensive, on the front end and operationally and upkeep and repairs. You should consider all of these to ensure you are prepared for these substantial and on going costs before you put it in your home. Also consider if you ever decide to sell it and move you will have to find someone else who is willing to take on a commercial maint program in their home. Remember not only do all of these components have to work they have to work to gather which means commercial control system of some type as well. I am not suggesting you not do what you are wanting I'm just suggesting you think very carefully about it. Research all of these costs and make a truly informed decision. You can have the cleanest bestest air in the whole neighborhood but it may bankrupt you to get it. Good luck.

  8. #8
    Join Date
    Oct 2012
    Posts
    87
    Quote Originally Posted by Tommy knocker View Post
    The quest for perfect IAQ can be very expensive, on the front end and operationally and upkeep and repairs. You should consider all of these to ensure you are prepared for these substantial and on going costs before you put it in your home. Also consider if you ever decide to sell it and move you will have to find someone else who is willing to take on a commercial maint program in their home. Remember not only do all of these components have to work they have to work to gather which means commercial control system of some type as well. I am not suggesting you not do what you are wanting I'm just suggesting you think very carefully about it. Research all of these costs and make a truly informed decision. You can have the cleanest bestest air in the whole neighborhood but it may bankrupt you to get it. Good luck.
    Exactly my desire - to stay out of BK but still have adequate air supply & exchange.

    I think based on my little info I posted above, I would hope that there is a 'right' package that some1 here could devised for me without costing $ & like you said maintenance time.

    The quest for a tight home has unfortunately caused an even costlier side effect.
    All these years, I've put up with smells & humidity in my home with no real ill effects.
    Now just wanting to step up a little in IAQ with our first custom home has been a real education.

    Being aware is expensive.

  9. #9

    New construction nex step

    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.
    Last edited by jpsmith1cm; 10-23-2012 at 05:19 PM. Reason: non AOP member

  10. #10
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,998
    okconstructioncorp


    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,070
    Quote Originally Posted by Ben44 View Post
    Thanks J Trammel for chiming in. Can't wait for the Bear to show up LOL! I've read his writings.
    Any how, are you suggesting that a dehumidifier can also serve as an ERV?

    Also, I've done some lite budgeting & it appears that a separate ERV & a whole house DH would run @ least $1K+ each?
    That's a big $2K expense that I rather not broach with the tight budget already of the new build. So seeking alternatives that meets the need would be preferable.
    I must appologize! This old bear missed your post and thanks for the support from my follow posters.
    Glad you are considering fresh air ventilation and humidity control. In moderate climates like yours, I suggest that a whole house ventilating dehumidifier will handle fresh air ventilation and maintain <50%RH when there is low/no cooling loads. 100 cfm of make-up fresh air ventilation is adequate for changing the air in your home in 4-5 hours. The fresh air ventilation is needed when the home is occupied and winds are calm.
    During cold windy weather most well built homes do not need supplemental fresh air ventilation. This is because the natural forces on the home will change the air in the home every 4-5 hours.
    The kitchen hood is a wild card. I suggest not using high speed exhaust unless you open a window or a dedicated make-up system. There are a few hoods that include make-up air as part of the design.
    Sorry about the mess-up on catching your original post.
    Regards TB
    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"

  12. #12
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    2,998
    * Foam roof lines/ cellulose attic/ closed cell batts for walls

    can you explain this a little better?
    foam roof line & cellulose?
    what are closed cell batts?

    glad to see you made it over here.
    but leave pricing out of posts.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  13. #13
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,649
    Quote Originally Posted by Ben44 View Post
    We are building a house:

    * Gas range - 4 burner with 600 CFM vent hood


    Non-sealed combustion appliances have no place in super-efficient homes.

    Gonna have babies? Ever heard of SIDS? You aware small children and elderly are highly susceptible to CO?


    Will this be the only gas appliance? Propane? I've seen really high CO levels on ranges - and counting on low CFM vent hood to magically remove CO is nuts.

    And when you call someone to "tune" this thing, good luck!! Bet they don't own a CO meter, so how they gonna get it burning efficiently - eyeball?

    Induction ranges are beginning to get rave reviews.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event