Honeywell thermostat keeps reversing valve energized?

Discussion in 'Solar and Geothermal Water Heating Forum' started by MichaelSK, Jan 17, 2020.


Does your thermostat keep the reversing valve energized when system is off?

  1. Yes

  2. No

  1. MichaelSK

    MichaelSK Member

    Oct 1, 2016
    North Central Florida
    Honeywell RTH7560 thermostat keeps the reversing valve energized even when “mode” is set to “off”. There is no need to keep a nominal 26vac on the (orange) lead, the reversing valve solenoid remains very hot when the system is not being used. I spoke with the Honeywell consumer help rep who stated that the thermostat should de-energize the valve when the mode is set to “off”.

    My concerns are: 1) this is the third thermostat (same model), 2) I called the technical guys at Honeywell and asked if there was a recall - he responded “no there is no a recall on that thermostat,” 3) my valve gets very hot 168 f after 10 minutes, 4) seems that this behavior would shorten the reversing valve life-span, 5) could be a fire hazard, 6) this thermostat is widely used, few consumers would be aware that the device is energizing their reversing valve when the system is off. Indeed, how many repairs and shortened system lifespans are r/t to this behavior?

    One last question, the consumer, i.e. nontechnical rep, stated that the thermostat should not be energizing the reversing valve - what’s your experience? IMHO, the reversing valve should only be energized in most heat pumps when the system is actually RUNNING in COOL; the thermostat should not be keeping the valve energized when the system is idle - perhaps for months at a time.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    I had a friend who had a problem like that, except it reversed ALL THE TIME, so his heating cycle used the auxiliary heat strips to overcome the cooling load, at an extremely costly, and nonrefundable, expense to him.
  3. Sponsor

    Sponsor Paid Advertisement

  4. fitter30

    fitter30 Member

    Feb 2, 2020
    Retired service tech
    Peace valley missouri
    Have you pull the wire off either o or b on the subbase to see if the valve powers down?
  5. WorthFlorida

    WorthFlorida The wife is still training me.

    Oct 28, 2009
    Orlando, Florida
    What brand of unit you have? Do you have AUX heat strips (two stage heat)? One stage cooling? You could have it miss programed it for the third time but I don't know what would keep the voltage connected to the O terminal 100% of the time. It is why a miss wire would be my first concern, then programming.

    Is this new thermostat & new install or did this problem just started The reversing valve de-energized places the system in heat pump mode, energized it is in cooling mode. There could be three things going on, miss wired, a short (chew wire, etc) or the thermostat is bad or programmed wrong.

    Remove the wire on the "O" terminal and check for any voltage on the wire, there should be no voltage. If there is, something is miss wired at the compressor or a shorted wire. Also check the O wire inside the air handler that it is free and clear of any other wire. If it goes to a terminal to connect to the wire going to the compressor, be sure no other wires are on it.

    If the thermostat has power on the "O" terminal in heat mode or off, it's a thermostat problem. Do check that the wire from the AUX terminal is not touching the O terminal. LOOK for SHORTS.

    Another thing you can try is reprogram the thermostat for a single stage cool only system and there will be no voltage on the O terminal since a cool only system has no reversing valve.
    Last edited: Feb 3, 2020
Similar Threads: Honeywell thermostat
Forum Title Date
Solar and Geothermal Water Heating Forum Use a Thermostatic Mixing Valve in a Solar Hot Water heat dissipator Jun 18, 2010

Share This Page