Results 1 to 12 of 12
  1. #1
    Join Date
    Jun 2011
    Location
    SW Ohio
    Posts
    224

    Tempstar and humidity question

    I just had a new Tempstar HP and gas furnance system installed about a month ago. I have the blower motor running 24/7 and the humidity setting set at 50%. The company that did the install is coming back out because they weren’t able to set the charge properly for the AC side due to the temperature but got it close. Would the charge not being correct allow the humidity to get over 60% in the house before it over cools to bring down the humidity? Another thing I have noticed is that the blower motor stops running after the unit has satisfied the call for cooling but then kicks back on a few minutes later.

    The old system (also a 3 ton) never had a problem with humidity just not able to cool the house.

    System info:

    F9MVE0802120A
    TCH636GKA
    END4x48L24A
    “Observer” Communicating Thermostat

    We currently have the temp set to 77 degrees but it will cool to 75 sometimes to get the humidity down to 50%.

    I have a cheap temp/humidity gauge in the basement that reads 71 degrees and close to 60% humidity. The same company is also going to put in a return in the basement. What would be "normal" humidity levels for a basement? The whole basement is spray foamed with closed cell insulation BTW.

    Thanks

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,595
    Don't run the fan constantly, leave it on AUTO. The water on the coil re-evaporates and keeps the humidity up. The fan stopping after a cool cycle tries to let water drain off the coil and probably helps reduce the issue but leaving it on auto would give you the lowest possible humidity.

    In the basement, probably will be high, other than a big dehumidifier, probably can't chage that.

    You do keep it pretty warm so unless it is really hot out, the unit won't be operating a lot so humidity would be a bit higher. Possible that the unit is a pinch low which can reduce humidity control too.

  3. #3
    Join Date
    Jun 2011
    Location
    SW Ohio
    Posts
    224
    We were suggested to run it on "on" to help with some room temperature differences. I have a feeling though that sealing up all the duct work helped with that more than running the blower all the time.

    Don't know if you noticed that the unit has a 4 ton coil installed. I have the AHRI for it that specs out the higher SEER rating but didn't know if that would help or hurt humidity levels as well?

    Yeah, my wife wants me to turn it down which I may do. We ran the old one at that temp because it struggled to go any lower.

  4. #4
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    Make sure the indoor coil has a TXV on it.
    A heat pump's superheat is usually set quite low, as low as even 7 to 9F SH, that should help with dehumidification; (heat pump systems have a suction line accumulator to protect from compressor slugging, thus allowing for lower SH settings).

    Basements are bad for high humidity; perhaps the new Return-Air will help some to improve air changes, but you may need a dehumidifier in the basement.

  5. #5
    Join Date
    Jun 2011
    Location
    SW Ohio
    Posts
    224
    Udarrell, without asking the installer is the TXV placed somewhere I could find it to see if I have one?

    I;m hopeing that the return will help get it a little lower down there.

  6. #6
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    Quote Originally Posted by rk05 View Post
    Udarrell, without asking the installer is the TXV placed somewhere I could find it to see if I have one?

    I'm hopeing that the return will help get it a little lower down there.
    If this ID; END4x48L24A is the fan coil of you new system?

    The 5th letter is X, standing for a TXV metered coil; P is the letter for a Piston metered coil.
    The TXV is located near the indoor coil in the plenum or coil case.

    I'm positive your HP HI-efficiency unit would have a TXV on the indoor coil.

    There is a way to tell using pressure gauges & covering part of the condenser air intake to the coils; but you are not licensed to do that.

  7. #7
    Join Date
    Jun 2011
    Location
    SW Ohio
    Posts
    224
    I would have to think that it would have a TXV installed too for the SEER rating it has.

    I will turn the blower to "auto" and see what it does to both the humidity and the balance between the rooms.

  8. #8
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,031
    I will turn the blower to "auto" and see what it does to both the humidity and the balance between the rooms.
    If that doesn't do the job; try lowering the blower CFM to 350-CFM per ton of cooling.

    Check the duct system & RA filter area for proper sizing, & for SA & RA duct leaks, which can cause many serious problems - including humidity problems.

  9. #9
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,770
    Quote Originally Posted by rk05 View Post
    I just had a new Tempstar HP and gas furnance system installed about a month ago. I have the blower motor running 24/7 and the humidity setting set at 50%. The company that did the install is coming back out because they weren’t able to set the charge properly for the AC side due to the temperature but got it close. Would the charge not being correct allow the humidity to get over 60% in the house before it over cools to bring down the humidity? Another thing I have noticed is that the blower motor stops running after the unit has satisfied the call for cooling but then kicks back on a few minutes later.

    The old system (also a 3 ton) never had a problem with humidity just not able to cool the house.

    System info:

    F9MVE0802120A
    TCH636GKA
    END4x48L24A
    “Observer” Communicating Thermostat

    We currently have the temp set to 77 degrees but it will cool to 75 sometimes to get the humidity down to 50%.

    I have a cheap temp/humidity gauge in the basement that reads 71 degrees and close to 60% humidity. The same company is also going to put in a return in the basement. What would be "normal" humidity levels for a basement? The whole basement is spray foamed with closed cell insulation BTW.

    Thanks
    Check the CFM setting, probably moving a lot more air then the old system did.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Jun 2011
    Location
    SW Ohio
    Posts
    224
    I switched it over to "auto" last night and it seems that it has helped because the humidity when I got home was 59% but after I switched it every time I walked past and checked the highest it was 55%. I'm going to leave it like that for a couple of days and seem if it holds it to 55% or lower.

    I also need to put my thermometer back into the bedrooms to make sure the temps are still staying close to the set point. That was a big problem we were having with the old system. The install company as well as myself sealed up all the ducts to those rooms and now the balance is much better.

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,638
    To get <50%RH, you need a <45^F cooling coil temperature. Measure the supply air temperature to the rooms. <50^F supply air is important to get dehumidification. Long cooling cycles are also important. <20 mins. cycles just load the cooling with moisture and with nothing going down the drain. Water left on the coil re-evaporates back to the home. With the fan on, it takes 40 mins. for the coil to dry. With the fan "auto" of off, it takes 1.5 hours to dry.
    If the a/c does not operate continuous for 1 hour, do not expect much dehumidification. If you want humidity control when there is low/no cooling loads, get a whole house dehumidifier like the Ultra-Aire whole house. As others posted, for homes with a basement get large dehumidifier like a Santa Fe. Dehus like mentioned are durable and high efficiency.
    Keep us posted.
    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
    Jun 2011
    Location
    SW Ohio
    Posts
    224
    Teddy, I will check the temps coming out and report back.

    It rained off and on yesterday and after I switched the fan to "auto" the humidity in the house seemed to drop. Today and especially tomorrow should be a good test since the weather man is calling for very humid days.

    Am I being a little on the miser side by keeping our AC set to 77? I know my wife would love it for the temps inside to be cooler maybe 75?

    I'm going to see what this summer brings for the basement humidity after I get the remodel complete. If the humidity stays up in the low 60's I may have to get a dehumidifier.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event