Ontario How to tell reversing valve direction

Discussion in 'Maintenance and Troubleshooting' started by Matthew Alberga, Dec 11, 2020.

  1. Matthew Alberga

    Matthew Alberga New Member

    Hello All.

    I have a 1991 Enertran Geothermal running on an open loop.
    Everything is working very well, the house stays at an even 70 degrees regardless of how cold it gets outside.
    However, some silly person 30 years ago figured it would be wise to put the thermostat(white-rodgers 9105-e7) in the corner of the home, beside an entry door.
    Being that it can be -15c to -25c for months on end here, Its not very wise, every time the door opens the Geo kicks in.

    Im going to move the thermostat to a new location(living room)
    As part of that move, I am considering an upgrade to the thermostat.

    One of the configuration points on the new thermostat is the setting for the reversing valve.

    Without having a Manual on this model groundwater heat pump, How can I test/validate what direction the reversing valve is set to? cool or heat?

    I would assume this matters based on the thermostat asking for this information.
  2. gsmith22

    gsmith22 Active Member Forum Leader

    I think you are going to have to explain this a little better. Presumably the reversing valve is currently in the position to heat, no?
  3. ChrisJ

    ChrisJ Active Member Forum Leader

    Most likely you can figure it out with the way the existing tstat is wired.
  4. Matthew Alberga

    Matthew Alberga New Member

    Thanks for the replies guys,
    I haven't done anything yet, I just want to make sure I do it right the first time if possible, "understand, then do"

    The question comes from reading this FAQ on the Ecobee website:

    For heat pumps, verify the O/B reversing valve is energized on the correct setting

    If you have a heat pump system, it's possible that your O/B reversing valve may be energized on the wrong setting. The easiest way to diagnose if this is the issue is by also testing your heat--is the air warm or cool? If the valve is energized on the wrong setting, you'll receive heat when calling for air conditioning and you'll receive air conditioning when calling for heat.

    When I read this, it would seem to me there are two ways a Geo can work: Energized on cool or Energized on Heat.
    meaning that there is a non-energized position? Like a "normally open, or a normally closed solenoid?"

    or does this mean "what is it currently energized on (right now)"
    Last edited: Dec 11, 2020
  5. SShaw

    SShaw Active Member Forum Leader

    This is not specific to geothermal. Heat pumps will have a reversing valve, which switches the heat pump from heating mode to cooling mode. The valve will operate in one of two ways: 1) O reversing valve (energized in cooling) or 2) a B reversing valve (energized in heating).

    If the O/B wire is disconnected (or not energized) an O system will operate in heating, and vice versa.

    To see what your current system is, you could use a voltmeter to see if your current TSTAT energizes the O/B terminal in heat mode. If so, you should read 24V AC between O/B and C terminals at the heat pump.

    If the setting is wrong on the new TSTAT, the system will operate in the opposite mode than called for. So, you could also just wire up the new thermostat, set the TSTA to call for heat and see if the heat pump works in heat mode. If not, just reverse the setting in the TSAT.
    Matthew Alberga likes this.
  6. Matthew Alberga

    Matthew Alberga New Member

    thanks a bunch!

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