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  1. #27
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429

    Thumbs up 52nd or Bust

    Originally posted by Carnak
    You mentioned that you opened windows before and were concerned about all the cold air at 0F. You may be interested in a heat recovery ventilator or HRV as pecmsg
    has already suggested.


    This is a successful system used in Canada
    AND OTHER Northern states.

    [Edited by Carnak on 10-28-2005 at 01:24 AM]
    Is one supposed to infer that Canada is our 52nd state?
    Please advise.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  2. #28
    Join Date
    Apr 2002
    Posts
    11,808
    The OP is in a northern state, is Puerto Rico or Mexico the 51st?
    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/

  3. #29
    Join Date
    Feb 2003
    Posts
    1,996
    Is that fresh air damper hooked up to the furnace ductwork? Might just be a fresh air suppliment to your duct system.
    Even if you have a 80 or 90% gas furnace with indoor combustion air, it doesn't change humidity levels in the home.

    With all that exposed concrete in the basement, I'd see if you have higher humidity levels down there. The concrete might be picking up moisture all summer and venting it off into the home during heating seson.

  4. #30
    Join Date
    Jun 2004
    Posts
    8
    There doesn't seem to be any difference in the humidity levels upstairs and downstairs. Additionally, I taped six 12" x 12" pieces of Al foil on the walls and floor of my basement (in various locations)...and after 3 days, there was no evidence of the slightest bit of moisture on any of them.

    I'm not sure I understand the comment about 'additional fresh air for the furnace...' Does that mean there are other air inlet for it?

    Thanks!

  5. #31
    Join Date
    Feb 2003
    Posts
    1,996
    Some FA systems have a duct off the return straight to the outdoors to pull fresh air in. Of course this causes more of a load on your system in both heat and cooling mode.
    During the winter this should bring in drier air from outdoors.

    What are your outdoor relative humidity levels durring the winter? If you have a 90%+ furnace, is water seen inside the unit from a clogged condensation drain. You might have a pool of water in the unit acting like a humidifier.

  6. #32
    Join Date
    Jun 2004
    Posts
    8
    I'm not experienced enough to tell if this duct is a 'seconary duct' or the main one? From looking at my basement ceiling, there's a lot of ductwork for this 'seconary' inlet...like 50+ feet worth...but maybe that's code or something? Right above the furnace, the ductwork utilizes the ceiling joices and flat sheet steel(to make bigger ducts) and I don't know if there's something that runs vertical from there (which I would assume has to go to the roof/attic?) that would then be the "main" inlet? Hard to tell. I do know that when I took off the 8' section on what I'm calling the secondary duct, there was a good amount of suction (I could certainly feel it). I still haven't removed this valve (traveling this week)...but maybe I'll give that a shot.

    I live in WI, so I assume my humidity levels are very low - as most people have to add humidity...

    I'm not sure I know enough to look into my furnace to look for water...might be time to call that HVAC guy!




  7. #33
    Join Date
    Nov 2005
    Posts
    2
    Is there a published residential indoor humidity recomendation based on outdoor temperatures?
    I have been told at 0ºf RH of 20% and increase RH 5% for every 10ºf.
    That sounds low to me and I need to make recomendations to people.
    If anybody knows for sure or can reference a link I would be grateful.
    It may clear up some other discussed issues as well....

    Thanks

  8. #34
    Join Date
    Nov 2005
    Location
    sacramento calif.
    Posts
    1,191
    ALL GOOD POINTS ,HERES ANOTHER CONDENSATION ON THE INSIDE OF WINDOWS IN COLD WEATHER IS THE SINGLE MOST OBVIOUS INDICATION THAT YOU HAVE A CRACKED HEAT EXCHANGER.CALL A REPUTABLE CONTRACTER WITH NO WARRANTY STAKE IN YOUR HEALTH.

  9. #35
    Join Date
    Mar 2004
    Location
    Cabot, PA
    Posts
    177
    Actually have a similar problem here in PA house is 2200sf radiant floor heat in all basement and garage floors and hydronic air handler that supplys the first floor living area pre-cast basement walls house is also 2 years old and moisture was a huge problem last winer so I installed a HRV AND IT SEEMED TO HELP BUT GOT A CALL A COUPLE WEEKS AGO FROM HO AND THEY STATED THAT THEY ARE HAVING CONDENSATION ON WINDOWS AGAIN. MY QUESTION IS THE HRV HAS NO TIME CONTROLL SO IT SEEMINGLY RUNS ALL THE TIME .and the HO unplugs it freequently to save electric should this HRV run all the time or should it run with some sort of timer?
    sorry about the caps but i wasn't retyping all of this

  10. #36
    Join Date
    Apr 2002
    Posts
    11,808
    Have it run off of a dehumidistat.

    Make sure the intake vent is not plugged up and the intake flex duct is not collapsed.

    Tell the ho to leave it plugged in and to stop hang drying laundry in the house.
    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/

  11. #37
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Originally posted by Carnak
    Have it run off of a dehumidistat.

    Make sure the intake vent is not plugged up and the intake flex duct is not collapsed.
    Whats the %RH setting that minimizes the run time of the HRV? In other words, operate the HRV for proper fresh air (10-12 hours/day), stop sweaty windows, without running continuously during routine +45^F dew point PA weather. A friendly TB

  12. #38
    Originally posted by t527ed
    if furnace does not dry out air then why are houses with hot air heat so much drier in winter time than a house with hot water heat???
    Warm air furnaces don't decrease humidity.


    I have herd that old wives tale of hot water system making the air"wetter", but that's just a misinterpeted observation our grandparents made. Back then they're were more steam raditors with leaky reliefs pouring steam into the occupied space.

    The generalization has stuck to this day.

    When the 80%s came into being the supply air was lower temp because more gas is being burned and that made for air that held LESS moisture, not MORE.


    Now we hav 90%s with even lower supply air temps.


    So a warm air furnace does not remove or add moisture.

    [Edited by curry on 11-10-2005 at 11:53 AM]

  13. #39
    Join Date
    Apr 2002
    Posts
    11,808
    Originally posted by teddy bear
    Originally posted by Carnak
    Have it run off of a dehumidistat.

    Make sure the intake vent is not plugged up and the intake flex duct is not collapsed.
    Whats the %RH setting that minimizes the run time of the HRV? In other words, operate the HRV for proper fresh air (10-12 hours/day), stop sweaty windows, without running continuously during routine +45^F dew point PA weather. A friendly TB
    The RH setting depends on the quality of the windows and how cold it is outside. A good starting setpoint in the heating season is 35% when it is below freezing out and 50% when it is above freezing out.

    Will not be a sweaty window problem when ambient dewpoint is 45F with a ventilated home. Running on a timer could control humidity, running by a dehumidistat will minimize run time especially in the coldest weather.




    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/

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