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  1. #14
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    we are mostly heat pumps,and it should be able to be set for 50%.No idea why yours won't go to 50%.

  2. #15
    I'm wondering if somehow the installer didn't setup the stat to indicate variable speed air handler? I also noticed in the install instructions that there was an option for super dehumidify mode (option 7) in the install manual. If this was not enabled (is it even an option with the FV4 coil?), do you think that could have an effect? Like you all said earlier, I guess it is just time to call the contractor.

  3. #16
    Join Date
    Feb 2003
    Posts
    275
    as my esteemed collouge stated software switc 7 must be on and so does 5 which signifies variable speed blower.

    now try to adjust it lower

  4. #17
    Join Date
    Apr 2005
    Location
    Kingston Ontario Canada
    Posts
    1,210
    Originally posted by kilobravo3
    Let me know if this question is out of line. If so, I will understand. In trying to setup my new Thermidistat with 38YDB heat pump and FV4A fan coil(new construction install). I tried to set the dehumidify function on the thermidistat. The manual says that the acceptible values are from 50% - 90%. For some reason, I can't get it to go below 60%. Did the installer forget something, or am I just doing something wrong?
    I have the same Thermidistat,and the same FV4A Fan coil. My thermidistat has the range of 50 to 90. But I find that if I use the cool to dehumidify function the heat pump short cycles at night when the cooling load is low. Any body any ideas?

    [Edited by thorton on 04-24-2005 at 11:47 PM]

  5. #18
    Join Date
    Apr 2005
    Location
    Kingston Ontario Canada
    Posts
    1,210
    Originally posted by kilobravo3
    Let me know if this question is out of line. If so, I will understand. In trying to setup my new Thermidistat with 38YDB heat pump and FV4A fan coil(new construction install). I tried to set the dehumidify function on the thermidistat. The manual says that the acceptible values are from 50% - 90%. For some reason, I can't get it to go below 60%. Did the installer forget something, or am I just doing something wrong?
    The guy's below are absolutly right, go into the configuration mode of your Thermidistat and select option # 5(variable speed blower) on, and option #7 variable speed superdehumidify. I'm sure then you will have the correct range of dehumidify (50 to 90)

    Thorton

  6. #19
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by thorton
    Originally posted by kilobravo3
    Let me know if this question is out of line. If so, I will understand. In trying to setup my new Thermidistat with 38YDB heat pump and FV4A fan coil(new construction install). I tried to set the dehumidify function on the thermidistat. The manual says that the acceptible values are from 50% - 90%. For some reason, I can't get it to go below 60%. Did the installer forget something, or am I just doing something wrong?
    I have the same Thermidistat,and the same FV4A Fan coil. My thermidistat has the range of 50 to 90. But I find that if I use the cool to dehumidify function the heat pump short cycles at night when the cooling load is low. Any body any ideas?

    [Edited by thorton on 04-24-2005 at 11:47 PM]

    Cool to Dehum.,should be 10minutes on ,10 off.Is that what you see happening?

  7. #20

    Dash

    I know it has been a couple of weeks on this one, but I just wanted to get some more info. We had a brief power outage and after that, the stat allowed me to set the humidity to 50(can't figure that one out!!). I also got the installer's guide and check the settings for #5 and #7...both look good. Now, here is the question regarding the cool to dehumidify function that was asked by someone else in this thread. My book says that it will overcool by up to 3 degrees in order to reduce the humidity. I have the stat set to 78 and the indoor temp is 78 with RH of 60. To me, it seems that the unit would come on trying to reduce the humidity until it hit the desired humidity, or 75 degrees, whichever came first. This is not happening though. When there is a dehumidify demand, the unit runs for 6 minutes. It turns off for some time (haven't timed this yet), but then runs again for 6 minutes. Either something is not right, or I have a complete misunderstanding of how this thing is supposed to work. Which is the case here?

  8. #21
    Join Date
    Apr 2004
    Posts
    7,680
    I'd buy a bigger hammer if I set my thermostat to 78 it would run as low as 75.

  9. #22
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,134

    Re: Dash

    Originally posted by kilobravo3
    This is not happening though. When there is a dehumidify demand, the unit runs for 6 minutes. It turns off for some time (haven't timed this yet), but then runs again for 6 minutes. Either something is not right, or I have a complete misunderstanding of how this thing is supposed to work. Which is the case here?
    Unit should run approximately 10 minutes and be off for same amount of time when there is a cool-to-dehumidify call. It is not a constant run down to 75F.

    From page 9 of your installation manual:

    During cool-to-dehumidify demand, the compressor runs a maximum of 10 minutes on, followed by 10 minutes off.
    Read page 9 slowly. The answers are all right there.

  10. #23
    OK. Thanks guys. I guess I just misunderstood how this was supposed to work. I saw the earlier post that said 10 minutes on/10 minutes off, I guess I just missed the "up to" part. 6 minutes just seems kind of random, but it is running that amount of time every time.

  11. #24
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,260
    Originally posted by kilobravo3
    OK. Thanks guys. I guess I just misunderstood how this was supposed to work. I saw the earlier post that said 10 minutes on/10 minutes off, I guess I just missed the "up to" part. 6 minutes just seems kind of random, but it is running that amount of time every time.
    It takes 6-8 minutes for the cooling coil to get cold enough to remove moisture. Recycling this quickly reduces the moisture removed vs. the sensible cooling. Keep us posted on the indoor %RH during cool wet weather with no cooling load. Contolling %RH with a dehumidifier is more comfortable and prevents moisture condensation on cold surfaces.

  12. #25
    It's been relatively cool here in FL the last couple of weeks. We've had a couple of days of rain and 75 degrees. The humidity tends to stay around 60%...sometimes creeps up to 63-64, and sometimes down to 57-58. I usually have to turn the stat down though to add a cooling demand in order to get the humidity in the 50's. Things are starting to warm up here, and I imagine as I have more of a cooling demand, the humidity will get under control. I guess I am too optimistic that I can get the humidity down in the low 50's in FL. I'd really like to have the temp around 78-80 with the low humidity, but usually have to turn the stat down to around 76 to get the humidity into the 50's.


  13. #26
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    If it's working as designed,it will control the humidity just fine,assuming no other problems ,like high infiltation,duct leaks,etc..

    I know because mine does,we have had very cool ,wet weather the past two months ,and it works.

    Keep the stat at 78 ,so the overcool,doesn't go below 75 and you'll be very comfortable.

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