Results 1 to 7 of 7
  1. #1
    Join Date
    Nov 2007
    Posts
    5

    Can I have "too much" fresh air?

    Hello all,

    I'm a homeowner with a question about ventilation in our home.

    The home is recent construction; sealed very tight, one stage gas furnace and one stage A/C.

    The builder specified the HVAC contractor install an AirCycler FR (not FR-V) as part of the HVAC system. For those who aren't familiar with the AirCycler, it basically makes a 10 minute call for fan whenever there has been 20 minutes without fan activity. The AirCycler releases it's call if the thermostat makes one.

    Connected to my return duct is an undampered six-inch flexible insulated outside air duct.

    As I understand it, the builder had at least two things in mind specifying the HVAC this way. First, it provides regular ventilation with fresh air. Second, the fan cycling helps "even out" temperatures throughout the house.

    We've lately taken to running the house fan continuously. A concern I have is that this undampered six-inch outside supply is providing us with more fresh air than we need, which would make our furnace work overtime and make the humidifier less effective.

    The AirCycler model FR-V would have been able to control an electric damper and only allow fresh air in when needed, but that isn't what we have.

    Do you think my concern about "too much" fresh air is off-base, or would you recommend I have a balancing damper (or FR-V controlled electric damper) installed?

    Thanks!

    P.S. - The furnace has a separate outside duct to provide combustion air.

  2. #2
    we've had to correct this in a lot of a homes from well-known builders...

    can you have too much fresh air? no....unless the air is too hot/cold/humid.

    my boss came up with a design he's got a patent on that uses a Lennox HEPA filter and some controls that sense outside humidity and temperature.

    if the conditions are right it opens the fresh-air intake and let's it cool/heat the house for the cost of running the fan.

    if conditions are too cold/humid/hot (as in rain or a -30 degree winter morning) it won't open that damper.

    Fresh Air is good..but if the intake is undampered there is nothing stopping humid, damp, cold air from adversly affecting your home and YES causing your heat/cool system to run FAR TOO MUCH.

    get that thing dampered and/or shut it off...and in the meantime to NOT run the fan all the time..especially with winter upon us. You'll have a coronary when your gas bill comes in otherwise.

  3. #3
    Join Date
    Jul 2006
    Location
    Anytown USA
    Posts
    2,064
    Quote Originally Posted by Comfort Queen View Post
    my boss came up with a design he's got a patent on that uses a Lennox HEPA filter and some controls that sense outside humidity and temperature.

    if the conditions are right it opens the fresh-air intake and let's it cool/heat the house for the cost of running the fan.

    if conditions are too cold/humid/hot (as in rain or a -30 degree winter morning) it won't open that damper.
    lol honeywell know about this patent?

  4. #4
    Join Date
    Nov 2007
    Location
    Chicago
    Posts
    76
    Quote Originally Posted by Comfort Queen View Post
    we've had to correct this in a lot of a homes from well-known builders...

    can you have too much fresh air? no....unless the air is too hot/cold/humid.

    my boss came up with a design he's got a patent on that uses a Lennox HEPA filter and some controls that sense outside humidity and temperature.

    if the conditions are right it opens the fresh-air intake and let's it cool/heat the house for the cost of running the fan.

    if conditions are too cold/humid/hot (as in rain or a -30 degree winter morning) it won't open that damper.

    Fresh Air is good..but if the intake is undampered there is nothing stopping humid, damp, cold air from adversly affecting your home and YES causing your heat/cool system to run FAR TOO MUCH.

    get that thing dampered and/or shut it off...and in the meantime to NOT run the fan all the time..especially with winter upon us. You'll have a coronary when your gas bill comes in otherwise.
    Your boss designed an economizer with a differential enthalpy sensor, pretty sure those have been around for a while.

  5. #5
    how about we worry about answering this guys questions then whether or not my boss has a patent on anything?

    All I know is he designed the set-up and controls..tested it...has a patent pending that Lennox supposedly wanted to buy from him.

    regardless that's not what this thread is about and honestly I could care less if it isn't true in some way ;-)

    so back to the question...shall we?

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,637
    You need fresh the correct amount of air when you are in your home. To hot, cold, humid, or what, does not make that much difference. In 7,500 degree days of heating, 75 cfm of fresh make-up air 10 hours a day cost $100 per year. Operating your fan on a very low speed continuously sucks in less air than at high normal heating/cooling speed. A adjustable damper would be nice Evidence of too much fresh air is low winter %RH. If you have a humidifier operating, you may well have too much fresh air.
    In green grass climates, the sign of adequate fresh air when the grass is growing is high indoor %RH. That is unless you have a whole house dehumidifier to maintain <50%RH during low/no a/c cooling load. There is a lot of misinformation on the web about these isssues. Our contractors are well intentioned but are not aways correctly informed. Its a fine line between not enough and too much. Confusing at best. What climate do live in? Season greetings, 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"

  7. #7
    Join Date
    Nov 2007
    Location
    Chicago
    Posts
    76
    Yes you can have too much outdoor air, but a 6" round depending on the length and how its installed, will not really bring that much outdoor air in just installed in the return air duct with no fan. Personally I would remove or reprogram your furnace so it isn't cycling on and off every 20 minutes and your setup should be fine.

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