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  1. #1
    Join Date
    Jan 2007
    Posts
    54

    HVAC in Crawlspace

    Currently building a new home and my HVAC contractor wants to put the gas furnance in the crawlspace. What are the positives and negatives by doing so. My crawlspace is about 6 blocks high where he wants to put it with a crawlspace door with in 8 feet of unit.

  2. #2
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    5,542
    There is almost nothing positive about equipment in a crawl space. Some companies won't service them as it's technically considered a confined space requiring two people with ventilation and communication. I know this is not common today but I believe it's coming.
    While you might save a little space in the living area in my experience crawl equipment doesn't get the extent of maintenance a unit in a more accessible space would.
    Ducts have to be carefully insulated to prevent condensation.
    Lets face it. Crawls are mostly nasty. Spiders, snakes, mice and the guy servicing the unit can't wait to get out. Not to mention he is covered with dirt and has to go to another call.
    Attic spaces aren't any better. These installs were some reasons I only do commercial.
    Tracers work both ways.

  3. #3
    Join Date
    Feb 2009
    Location
    pinehurst north carolina
    Posts
    54

    Cool

    Quote Originally Posted by Bigdog8 View Post
    Currently building a new home and my HVAC contractor wants to put the gas furnance in the crawlspace. What are the positives and negatives by doing so. My crawlspace is about 6 blocks high wh ere he wants to put it with a crawlspace door with in 8 feet of unit.
    There are both positives and negatives. The negatives are its under the house and subject to animals getting in and messing with the ductwork or equipment, could be that the maintenance person does poor work because you can't see him. I live in NC and don't know that I've ever heard of a person not working on a unit because its under the house unless the house is real low and the person is real big or there are issues like standing water or snakes or something else like that, its not at all common for companies to refuse work.
    The positives are that while its under the house you don't have all the equipment operating noise that you would if it was inside the space, the venting is all easily accessible to work on if there is a problem, the ductwork is the same easily accessible if it needed balancing or ever got messed up it could be easily replaced or cleaned, no special insulation required of course if you were running the duct in a conditioned space then its not needed to be insulated at all,better options at space requirements for enlarging returns or supplies, less chance of condensate leak ruining flooring, most importantly any repairs are going to be done outside of the house which means the walls don't get banged up, the floors don't get mud tracked in or scratched up.
    Of c ourse if you put it in the attic you've got a whole bunch of other issues so if I had my choice and trusted the hvac company I contracted and knew beyond a shadow of a doubt there would'nt be any changes I'd put it in a mechanical room but if not I'd go in the crawl space as long as it is pretty high. hope that helps

  4. #4
    Join Date
    Jan 2008
    Posts
    38
    Put it as close to the door as you can and you'll have no problem.

    It's only a pain when you have to crawl the width of the house to get to it.

    Like mine.

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    Crawlspace better than the attic. Provide enough space to work around the unit. Make your crawlspace dry by placing a durable vapor barrier on the earth to stop moisture from the earth. Also seal the space to stop outside moisture from entering the space. Keep the humidity below 55% RH in all inside spaces throughout the year. Provide fresh air ventilation when the home is occupied. An air change every 4-5 hours during occupancy is suggested by most codes and IAQ experts. Green grass climates with adequate fresh air ventilation need supplemental dehumidification. A new home should be healthy and comfortable during typical weather. 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"

  6. #6
    Join Date
    Dec 2007
    Posts
    4,710
    where is the air filter going?
    if it is at the unit are you going to change it or call a company to do it every time?
    as mentioned already, make it as worker friendly as possible; clean, lit properly( light in the correct location, tall enough tech does not have to lay down to service, dry, etc.), large access for any size person and tools, and remember it WILL have to be replaced at some time so think about getting a new unit in there and the old one out.
    if this HVAC guy wants it there, hope he will thik of all these things and any others.

  7. #7
    My crawlspace is rather comfortable and cozy.

  8. #8
    I had no problem doing it, my boss would have us put down a layer of poly under the unit that was about 10 feet square.
    (The wise men of modern thought) adore a god made of putty or of wax - plastic, effeminate, molluscous, with no masculine faculty about him, and no quality that entitles him to the respect of just and honest men, for a being who cannot be angry at wrongdoing is destitute of one of the essential virtues, and a moral Ruler who is not angry with the wicked, and who refuses to punish crime, is not divine. ---Spurgeon

  9. #9
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    5,542
    I do remember one nice system where the equipment was in a full height area of concrete like a small basement. All mechanicals were in this area.
    Tracers work both ways.

  10. #10
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    insulate the cawl walls [not bottom 4"]
    provide drain from crawl
    consider a concrete pad for furn & space in front, sidewalk to door.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    A forgotten point is that any air leakage moves to the house through the crawlspace floor and no heat/loss compared to the hot/cold attic.
    In cold climates, there are big condensation problems inside the ducts during cold weather.Monitor the %RH in the crawlspace, dehumidify when needed. Accurite has a neat remote %RH meter, WalMart $29. 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
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    whether in a crawl space or an attic;

    anytime a unit has to be put in a horizontal position

    IMHO, i would say that automatically knocks a few years off the life of the airhandler

    airhandlers, work better, seal up better, drain better when they are in a vertical installation

    but if i had to choose between the crawl space and the attic, i would choose the crawl space.



    .



    .

  13. #13
    Join Date
    Feb 2009
    Location
    Arnold, Mo
    Posts
    13

    Need more options

    I could come up with all kinds of negatives. It appears to me that equipment in crawl spaces don't have the longevity as other installations do.

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