Page 3 of 5 FirstFirst 12345 LastLast
Results 27 to 39 of 57

Thread: HRV or ERV?

  1. #27
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by goldenear View Post
    Well dry is a relative term, right? For me personally, the past couple of weeks have brought the coldest, driest air that I can ever remember. This has been a brutal beginning to February, so much so that I'm thinking of moving, lol. In order for my house to avoid condensation on the windows right now, I'd have to maintain an indoor RH of probably <20%. That's great for the house but horrible for us humans.

    Ask any otolaryngologist about indoor RH during the heating months and they're going to tell you to definitely keep it above 30%, preferably no lower than 40%. So there's a conflict between the building scientists and the medical professionals. Some people can get away with temporary bouts of extremely low indoor RH. Others like me who have really bad vasomotor rhinitis, which seems to triggered by large swings in RH, temp, and barometric pressure, or those who have a house full of occupants with viral and bacterial upper respiratory infections, have little choice but to say to heck with the wooden casement windows - let 'em rot in winter, I'll fix 'em in the spring.

    Windows really are the weak link in the building envelope, assuming everything else is properly sealed and insulated. Unfortunately, if you don't build, then you're stuck with whatever came with the house (usually inadequate even in new construction) and that will ultimately determine your indoor RH if you're absolutely committed to maintaining a condensate free interior.
    You need better windows then. NW Ontario they can maintain 35% when its minus 30C
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  2. #28
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Quote Originally Posted by goldenear View Post
    I agree, but here in southeast WI, the past stretch of 10-20 days has been an extreme and definitely not the norm for the 6-7 months of the heating season (Oct-Mar/Apr). So you've got, at the most, one month out of let's say avg. of 6.5 months that there's no ROI on an HRV (ERV is beneficial the remainder of the yr in this climate, esp with a family affected by seasonal allergies, so opening windows is not advised).
    Consider that a home that gets enoughfresh air during the coldest months requires only small amount supplemental fresh air during the milder winter months. You are dealing with small amounts supplemental fresh air with small temp differentials during mild weather. Therefore the payback is much reduced. The energy saved is less than $100 for the year when compared to an optimized simple make-up air ventilating system. My concerns are that after spending a lot of money for a hrv, most will not provide fresh air ventilaiton during summer while maintaining <50%RH. Regarding IAQ, summer fresh air with <50%RH is much more critical supplemental winter ventilation. Dust mites and mold cause more IAQ problems a little window condensation. Do both if you have the money, but do not neglect summer needs. TB

  3. #29
    Join Date
    Apr 2002
    Posts
    11,808
    My cousin married a chiropracters daughter.

    Her father used to crack her back when she had a cold, quite a cure all
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  4. #30
    Join Date
    Feb 2007
    Posts
    2

    ERV for ICF home in utah?

    I am wondering about how to attain replacement or fresh air in an ICF constructed home. ERV or HRV?
    Also, if humidty is something to be too concerned with in a tight home in Utah, the second driest state in the nation. (our skin gets so dry here, we all look like lizards in the winter).
    The home is designed around passive solar gain in winter for some heating, radiant heating in concrete slabs.
    Passive breezes through open windows for summer cooling. (It will have ducts for air conditioning system).
    Any help or suggestions would be appreciated.
    Steve

  5. #31
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Quote Originally Posted by regulajo View Post
    I am wondering about how to attain replacement or fresh air in an ICF constructed home. ERV or HRV?
    Also, if humidty is something to be too concerned with in a tight home in Utah, the second driest state in the nation. (our skin gets so dry here, we all look like lizards in the winter).
    The home is designed around passive solar gain in winter for some heating, radiant heating in concrete slabs.
    Passive breezes through open windows for summer cooling. (It will have ducts for air conditioning system).
    Any help or suggestions would be appreciated.
    Steve
    You live in an arrid climate winter and summer. Probably with the clothes drier, bath fans, and kitchen hood in 2,500 sqft. 4 people, 75 cfm of fresh infiltration will be ok. Get good bath fans that you can operate extra hours during the coldest weather for extra boost. Any wood burners or fireplaces. If yes suggest some make-up air to assist the chimineies. TB

  6. #32
    Join Date
    Feb 2007
    Posts
    2
    Teddy,

    Thanks for your reply. Here are a few more details.

    The home is two levels, main and lower, 4000 square feet total with five people and a dog. It wiill have a gas burning fireplace on the main floor. The bath fans, 4 of them, will be very good, I believe they are about 200 CFM each and will vent outside the home.
    The kitchen range hood, centrally located in the homes main floor, is rated up to 1400 CFM on high, although I doubt we will run it on high very often.

    Any other suggestions or ideas would be appreciated while we are still in the design phase.

    Thanks again,
    Steve

  7. #33
    Join Date
    Oct 2003
    Posts
    45
    Quote Originally Posted by Carnak View Post
    You need better windows then. NW Ontario they can maintain 35% when its minus 30C
    Have known this for some time now. These are Hurd casement windows and there really aren't any better options here in the States. What brand are you talking about and are those wooden casement windows?

  8. #34
    Join Date
    Oct 2003
    Posts
    45
    Quote Originally Posted by regulajo View Post
    The bath fans, 4 of them, will be very good, I believe they are about 200 CFM each and will vent outside the home.
    That number seems a bit high. Average vent rating for bath fans is about 75 CFM. Regardless, with that size of a range vent, you're going to need makeup air because even deliberately running a 200 CFM ERV out of balance (something no manufacturer would ever "officially" recommend), it won't come even remotely close to balancing your home's air envelope.

    An HRV doesn't make any sense for you because, assuming you'll provide secondary humidification at least during the heating season, it will just suck out all of the moisture that you introduce into the air. If it were me, I'd ditch the bathroom vent fans altogether and source point ventilate all of them instead, ducting each one into an ERV to recover as much moisture and heat as possible which will transfer that energy to the incoming fresh air.

  9. #35
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    >>The kitchen range hood, centrally located in the homes main floor, is rated up to 1400 CFM on high

    I wonder what kind of ducting you have for a fan of that capacity? Just trying to learn. The more I learn about ducting, the more I feel the need to respect its problems.


    With those bath fans, sounds to me like you might easily see 1000 cfm total exhaust, with a tight house that sounds interesting. I'm sure there is a simple and probably elegant solution to keep your chimney from being the intake shaft.

    Best of luck -- Pstu

  10. #36
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Quote Originally Posted by regulajo View Post
    Teddy,

    Thanks for your reply. Here are a few more details.

    The home is two levels, main and lower, 4000 square feet total with five people and a dog. It wiill have a gas burning fireplace on the main floor. The bath fans, 4 of them, will be very good, I believe they are about 200 CFM each and will vent outside the home.
    The kitchen range hood, centrally located in the homes main floor, is rated up to 1400 CFM on high, although I doubt we will run it on high very often.

    Any other suggestions or ideas would be appreciated while we are still in the design phase.

    Thanks again,
    Steve
    Forget about ERV/HRV. You biggest problem will be operating all that exhaust equipment. Make sure all of the gas appliances are power exhaust to avoid backdrafting. You may need powered make-up at least for the kitchen hood. Maybe a custom designed make-up air on your furnace?? Only operate the on high with window/door open. Most do onle 50% of claim. That's still to much. You need a good a/c designer. A scared TB

  11. #37
    Join Date
    Oct 2003
    Posts
    45
    The more I think about your situation, the more I believe these "who can produce the biggest residential kitchen vent" contests to be an exercise in complete futility. No residence on Earth needs 1400 CFM of exhaust unless you're doubling as a commercial food preparing facility. Even then, that's overkill for that size of a space.

    My wife can cook the most obnoxious smelling food (not her cooking, lol, just the nature of the food material) without using ANY kitchen exhaust, and I can have the entire house cleaned out in a couple of hours using a 200 CFM ERV (not even installed in source point vent - just simplified volume). This is a 2500 sq ft ranch with the same layout in the conditioned lower level, so 5000 sq ft total (main floor 9' ceilings with cathedral great room and lower with 8' ceilings, so that's a decent amount of air).

    Although that's not the ideal method, it just goes to show you that these ridiculous kitchen vents are simply not needed in residential applications. People are being oversold everyday on these stupid things. But the real story is they cause more problems in terms of balancing the home's air envelope than is necessary.

  12. #38
    Join Date
    Dec 2000
    Location
    Michigan
    Posts
    724

    Hmm If one is good, then two is better

    “With those bath fans, sounds to me like you might easily see 1000 cfm total exhaust, with a tight house that sounds interesting. I'm sure there is a simple and probably elegant solution to keep your chimney from being the intake shaft.

    Best of luck – Pstu”

    Yes there is a KISS solution—however, it is very high tech and complicated, it is called “opening the kitchen window” when the fan is on and don’t stand in the way of the air flow (wind chill)!!!! My window and ERV/HRV comments which you so often do not understand are supported by the following posts!


    teddy bear " Forget about ERV/HRV. You biggest problem will be operating all that exhaust equipment. Make sure all of the gas appliances are power exhaust to avoid backdrafting. You may need powered make-up at least for the kitchen hood. Maybe a custom designed make-up air on your furnace?? Only operate the on high with window/door open. Most do onle 50% of claim. That's still to much. You need a good a/c designer. A scared TB

    goldenear “My wife can cook the most obnoxious smelling food (not her cooking, lol, just the nature of the food material) without using ANY kitchen exhaust, and I can have the entire house cleaned out in a couple of hours using a 200 CFM ERV (not even installed in source point vent - just simplified volume). This is a 2500 sq ft ranch with the same layout in the conditioned lower level, so 5000 sq ft total (main floor 9' ceilings with cathedral great room and lower with 8' ceilings, so that's a decent amount of air).”

    You failed to identify the cost to "condition" the 24,000 cubic feet of outside air you are exchanging in the two hours as a factor too!

    To avoid the requirement for large kitchen range exhaust fans, I think they invented outside barbecues!
    The quality of my performance, sometimes depends on the quality of my audience.
    Imitation (Plagiarism) is the best compliment one can get -- "Open A Window"

    To improve Indoor Air Quality: Control Indoor Air QUANTITY = "I.A.Q.Q."

  13. #39
    Join Date
    Oct 2003
    Posts
    45
    Quote Originally Posted by Xavier View Post
    You failed to identify the cost to "condition" the 24,000 cubic feet of outside air you are exchanging in the two hours as a factor too!
    And you failed to identify the cost to condition the outside air flowing through your open window to balance the air envelope while running all of the exhaust vents. Our kitchen doesn't have any windows since it is in the center of the home - just a patio door. During the past couple of days, if I had to open that door while cooking, the kitchen would have been full of snow. The average lot size in our neighborhood is 3 acres and when it snows, it often falls horizontally because there aren't any metropolitan structures to block the howling wind. Right now, there's a six foot high snow drift in front of our front porch.

    You're obviously absolutely correct, though. And that's why we use an appropriately sized kitchen vent to exhaust the odors before they permeate throughout the home. I simply provided this example to illustrate the "retardedness" of using commercially sized kitchen vents in typical residential applications.
    Last edited by goldenear; 02-28-2007 at 01:13 PM.

Page 3 of 5 FirstFirst 12345 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