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  1. #1
    Join Date
    Jan 2007
    Posts
    115

    Rheem 90RJ Fan Speed Change

    My folks have a home new to them that is having humidity problems. Running around 60%.. Long standing lung problems etc.. already in play, I need to get the humidity down.

    It seems easy enough to drop the fan speed on cool down to medium, but I don't want to do something that will create a pressure problem and/or slug the compressor.

    Still, I sorta think the expansion valve will handle that concern and I'll get just what I want: increased latent cooling, decreased sensible...

    Fan speeds (short of a static test) are:
    Hi = 1135 cfm
    M = 960 cfm
    L = 790

    Heats on the low, cool is on the high. I'm thinking I move to cool, and the reduction seems in line with what I want, but...

    Am I thinking wrong here?

    And, does anybody have a manal for one of these?

    Thanks guys! dan

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,298
    You left off the most important detail: what size A/C? And the static needs to be checked before any speeds are changed as few duct systems are any where near as low as .5

  3. #3
    Join Date
    Jan 2007
    Posts
    115
    Hey Boldloonie. Mod huh? I don't remember that from over the years I've been coming and going. Thanks for the time committment to helping this board. A great forum.

    I've got his A/c specs at home, but I'm at work so I'll have to check back in again later. Static won't be so easy. Any way I can get that on my own? Or a good rule of thumb to estimate it?

  4. #4
    Join Date
    Jan 2007
    Posts
    115
    Mr: Loonie sir:

    13 seer, 2 ton Rheem. 13AJA.

    I'm probably not reading the specs right, but Rheem specs show almost all condensors for that call for 800 cfm, some smaller. Only two call for more, and that's 820 CFM.

    Heck, even @ .7kpa the blower, on medium, does 835 CFM.

    Course, just because that's all the farther chart goes doesn't mean its not worse, and I've zero, and I'm mean zip, knowledge on how to judge it. If it matters's it's ranch with a full 9' basement. The ducting can't be too byantine.

    And as long as it's at least close, doesn't the TXV handle this? Or do I have it wrong again?

    As always, my thanks to any and all;

    dan

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,298
    Yea, low would be the appropriate speed for cooling unless your static is outrageously high.

  6. #6
    Join Date
    Jan 2007
    Posts
    115
    Thank you. However, low is already on the heat side (this thing has a terminal that interfaces fan speeds to calling condition). I could parallel the low speed wire to both terminals easy enough. If that isn't a problem. Or I could move low to the ac side and put medium on the heat.

    Or just put medium on the cooling side.

    Mind given me the lesser of the evils advise?

  7. #7
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,298
    I'd either tie both on low or move heat to medium.

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