Convert Mobile Home to Central Air; Have Central Heat

Discussion in 'HVAC Heating & Cooling' started by kailor, Dec 3, 2010.

  1. kailor

    kailor New Member

    Messages:
    22
    Location:
    Huntsville, Alabama
    What size outdoor compressor should I get for a 14' x 66' MH? I already have central heat. I have always heard the rule is 1 ton of unit for every 600 sf. of heated and cooled living space. I will need to get an "A" coil also. Anything to consider with that?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    Rule of thumb can be quite expensive! You need to do a manual-j heat load analysis. If you do a search, you can probably find a free calculator, or have the vendor do it for you. It depends on the insulation, windows, orientation, and local ambient conditions. AL can be quite hot and humid. To remove the humidity means if the a/c is too large, it won't run long enough to pull the moisture out of the air and you'll be cold and clammy. You're better off with one slightly small verses one too big as you'll be more comfortable at a higher temp if the humidity is low, verses cold, but clammy.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    It is tough to do a rough guess on a mobile home, because your construction and insulation are different, possibly minimal. How many BTU is your furnace? I am guessing it may be relatively small, in your climate. You will have to determine from the manual for that heater how many tons of A/C the blower will support. But since you are well under the 3 ton range, it is likely that will not be a problem. A local HVAC guy should be able to figure this out.

    Yes, you need a cased coil attached to the furnace. Is there room on top of the furnace for that, where it sits?

    Around here, you could get the coil and a 1½ T R410 condensing unit , installed, between $3k and $4k.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,026
    Location:
    Cave Creek, Arizona
    An area enclosed by glass will need a much LARGER heating/cooling unit, than one completely enclosed with well insulated walls. The size unit you need will depend on your window areas, the orientation of you mobile home, the insulation in the walls, floor, and ceiling (probably minimal). Too small and it will run continuously. Too large and it will not run often enough to provide the needed dehumidifying in the area.
  5. gator37

    gator37 Retired prof. engr.

    Messages:
    108
    Location:
    Alabama
    jadnashua is correct about sizing

    but if you get an estimate on a condenser, refrigerant lines, A coil and electric to your condenser plus a new heat/cool T-stat, you might want to consider a package unit, gas heating electric cooling with either propane or natural gas what ever is available in your neighborhood . Then you can remove the furnace, patch the duct, and have closet space for shelves or something useful. They could run metal round to the center of the existing air supply line add a return grill w/ return duct in you living room and insulate the duct with foil back wrap under the mobile home.
    By the way I live just outside of Huntsville in Madison County.
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