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  1. #1

    Humidity Control with Lennox Comfort Sense 7000 T-stat

    I recently had the following new systems installed in my home:

    - 1st floor: Lennox 15GCSX Heat Pac with Lennox Comfort Sense 7000 T-stat
    - 2nd floor: Lennox XC15 and G60V furnance with Lennox Comfort Sense 7000 T-stat

    The system has been running for about a week now but the humidity level still remains fairly high (between 67 and 69% according to the RH reading on the t-stat). At this point I am wondering if there is a problem. Since the RH is not reaching the 50% setpoint, the system only runs in dehumidification mode and keeps the temperature 2 degrees below the temperature set point (the dehumidification temperature variance). I put another Honeywell humidistat directly on top of the t-stat and it reads a much lower RH than the t-stat does. So I am wondering if the humidistat on the t-stat is not very good or if the entire system is having issues removing humidity from my house. The settings on the t-stat are:

    - Dehumidification mode: Precision
    - Compressor Stages: 1
    - Fan Mode: Circ (35%)

    Any feedback/suggestions would be appreciated. Thanks!

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,346
    Does the air in your house actually feel "sticky"? If you were truly running 70% relative humidity at normal room temperatures, it would seem your main complaint would be one of discomfort vs. run time of the system and accuracy of the humidistat.

    It is possible the humidity sensor on the thermostats needs calibration.

    If you are feeling sticky, set the fan mode so it does not circulate at 35%, but only runs when the a/c runs. See if that improves your humidity readings and your comfort levels.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,441
    Quote Originally Posted by njrefugee View Post
    I recently had the following new systems installed in my home:

    - 1st floor: Lennox 15GCSX Heat Pac with Lennox Comfort Sense 7000 T-stat
    - 2nd floor: Lennox XC15 and G60V furnance with Lennox Comfort Sense 7000 T-stat

    The system has been running for about a week now but the humidity level still remains fairly high (between 67 and 69% according to the RH reading on the t-stat). At this point I am wondering if there is a problem. Since the RH is not reaching the 50% setpoint, the system only runs in dehumidification mode and keeps the temperature 2 degrees below the temperature set point (the dehumidification temperature variance). I put another Honeywell humidistat directly on top of the t-stat and it reads a much lower RH than the t-stat does. So I am wondering if the humidistat on the t-stat is not very good or if the entire system is having issues removing humidity from my house. The settings on the t-stat are:

    - Dehumidification mode: Precision
    - Compressor Stages: 1
    - Fan Mode: Circ (35%)

    Any feedback/suggestions would be appreciated. Thanks!
    With Fan recirc at 35% without a high cooling load or a dehu is difficult. Are providing any fresh air ventilation?
    There is method to check your portable %RH meter. A cup with a couple tablespoons of wet salt in a sealed plastic bag and %RH meter should read 75%RH. All so cooling a shiny metal bowl with ice/water down to the moisture condensing temperature on the cool surface determines the dew point of the air. Knowing the air temp/condensing temp determines the %RH. Regards TB
    Regards TB
    Last edited by teddy bear; 06-03-2009 at 12:31 PM. Reason: missing words
    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"

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,090
    Is that 2-5 ton units on a 2000 sq ft house.
    Or 2-2 ton units on a 4000 sq ft house.
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    How many times must one fix something before it is fixed?

  5. #5
    Quote Originally Posted by beenthere View Post
    Is that 2-5 ton units on a 2000 sq ft house.
    Or 2-2 ton units on a 4000 sq ft house.
    Total sq ft = 2300 with the 2nd floor being larger, probably 1000 sf on the 1st and 1300 sf on the 2nd. The 1st floor unit is 2 ton and the 2nd floor unit is 2.5 ton.

  6. #6
    Quote Originally Posted by shophound View Post
    Does the air in your house actually feel "sticky"? If you were truly running 70% relative humidity at normal room temperatures, it would seem your main complaint would be one of discomfort vs. run time of the system and accuracy of the humidistat.

    It is possible the humidity sensor on the thermostats needs calibration.

    If you are feeling sticky, set the fan mode so it does not circulate at 35%, but only runs when the a/c runs. See if that improves your humidity readings and your comfort levels.
    Actually, it feels comfortable and not "sticky". I read on another post that running the fan more often causes more humidity and it sounds like you are suggesting the same. I originally had the fan set to run continuous with the idea that it would improve the air quality. I just recently knocked it down to Circ -35%, but I will change it to Auto as you suggest and see if that makes a difference. I'm guessing calibrating the t-stat is not something a homeowner should attempt? Thanks for the feedback.

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