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Thread: Reversing valve wiring issue

  1. #41
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    Quote Originally Posted by theoldscroll View Post
    See post #2 thermostat with both o and b terminals. I'm still sayin it's a bad idea to not match HP and AH in the first place, but hey it's just one old guy's opinion.
    I ASSUMME the OP is speaking of the BOSCH Inverter Unit. (Nice Unit BTW) Agreed it should be matched but is forgiving.

  2. #42
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    I'm pretty sure that this is not an AHRI matching system. I don't see Trane matching the TEM air handler with anything other than a Trane product. The proper fix, per Trane or Bosch, is to change out the AH to match the Bosch Heat Pump.

    Quote Originally Posted by theoldscroll View Post
    See post #2 thermostat with both o and b terminals. I'm still sayin it's a bad idea to not match HP and AH in the first place, but hey it's just one old guy's opinion.
    Philippians 4:13
    I can do all things in him that strengthen me.
    Apostle Paul inspired by GOD.

  3. #43
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    Install a single throw double pole relay with a nc and no switch.
    “You don't get paid for the hour. You get paid for the value you bring to the hour.” Jim Rohn

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  5. #44
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    Quote Originally Posted by AtticAce View Post
    Install a single throw double pole relay with a nc and no switch.
    That makes it too easy!

  6. #45
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    Quote Originally Posted by brainsboy View Post
    Here is what i want.

    In cool mode i want to energize ah "o" and not energize Rv "o" to condenser.

    In heat i want to not energize ah"o" and energize Rv "o" on condenser

    The issue is some of you think "o" is dead on airhandler and im wasting time. Just wire for the rv and be done with it. As one person pointed out by schematic that the ah "o" does need to be wired correctly for blower speed based on heat vs cool.
    Back up. Yes O does need to be wired correctly but that depends on what you need for an end result. What do you want as the end result, ie I want the blower to do X on heat Y on cool, or airflow on heat and cool equal just need to switch RV, etc. There are many ways to do several different things with these air handlers and they don't all include the O terminal.

    So back to the question not mentioning terminals "what do you want to accomplish". What does the heat pump need from the air handler? Do you need more than 1 speed in heat and/or cool? Do you need different speeds for heat then cool. Do you just need to energize teh RV in the correct mode? What do you need/want?

  7. #46
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    Easy peasy 👍🏻 and Artietech is spot on !

    Some members here may need to offer the new guy an apology.
    I'll be the first.....
    Sorry for the confusion and welcome to the site.
    Please apply for Pro Membership so we can keep these discussion out of the open forums.
    Thanks

  8. #47
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    Whether that particular AH needs to see "O" for cooling or not, if you add a relay to the outside unit then you're covered either way.
    If you're not 100% sure whether or not it's needed, then it just takes all the guesswork out of the equation & for an HVAC tech it's a very simple job.
    Gary
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    http://www.oceanhvac.com
    The best things in life are free but not everyone is willing to pay the price.

  9. #48
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    i just copied and pasted this from a tem6 installation manual.

    Sequence of Operation
    Cooling (Cooling only)
    When the thermostat calls for cooling, the circuit
    from R to G is completed. The blower motor is
    energized directly by the ECM fan control, which
    receives the 24VAC signal from the thermostat.
    The circuit from R to Y is also complete energizing
    the compressor contactor of the outdoor unit. The
    contactor will close and start the compressor and
    condenser fan motor.
    Cooling (heat pump)
    When the thermostat calls for cooling, the circuit
    from R to G is completed. The blower motor is
    energized directly by the ECM fan control, which
    receives the 24VAC signal from the thermostat.
    The circuit from R to Y is also complete energizing
    the compressor contactor of the outdoor unit. The
    contactor will close and start the compressor and
    condenser fan motor.
    Circuit R to O energizes the reversing valve to the
    cooling position.

  10. #49
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    Quote Originally Posted by Artietech View Post
    On the Trane TEM units, the EEV profile is based on the "O" input from the thermostat. PLUS the ECM blower needs to see "O" for its cooling profile. Does not matter if communicating or 24v system. "O" tells the EEV to control superheat, while no "O" tells the EEV to open up for heating operations.
    are you talking about a TAM or a TEM? I did not think TEM had EEV but a TXV.

  11. #50
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    Quote Originally Posted by DOGBOY View Post
    i just copied and pasted this from a tem6 installation manual.

    Sequence of Operation
    Cooling (Cooling only)
    When the thermostat calls for cooling, the circuit
    from R to G is completed. The blower motor is
    energized directly by the ECM fan control, which
    receives the 24VAC signal from the thermostat.
    The circuit from R to Y is also complete energizing
    the compressor contactor of the outdoor unit. The
    contactor will close and start the compressor and
    condenser fan motor.
    Cooling (heat pump)
    When the thermostat calls for cooling, the circuit
    from R to G is completed. The blower motor is
    energized directly by the ECM fan control, which
    receives the 24VAC signal from the thermostat.
    The circuit from R to Y is also complete energizing
    the compressor contactor of the outdoor unit. The
    contactor will close and start the compressor and
    condenser fan motor.
    Circuit R to O energizes the reversing valve to the
    cooling position.
    Post #29
    And the TEM6 on his configuration only gets a Y call for both cool and heat the only way the air handler knows which speeds to use is via the use of O.

  12. #51
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    sorry, never noticed that heat pump and ac were 2 different cfm's.

  13. #52
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    Quote Originally Posted by DOGBOY View Post
    sorry, never noticed that heat pump and ac were 2 different cfm's.
    The Bosch is an Inverter Driven Heat Pump with Mitsubishis drive and compressor. Heat pump speed shouldn't matter as the pump will ramp up and down accordingly!

  14. #53
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    Quote Originally Posted by DOGBOY View Post
    sorry, never noticed that heat pump and ac were 2 different cfm's.
    I think your correct on the TXV involved because I only saw a mechanical one in that manual.

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  16. #54
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    I am still waiting to find out what he wants to accomplish. Most heat pumps can run just fine with the same CFM for heat and cool. 2 stage heat pumps will need a speed change between 1st & 2nd stage but can still run the same heat or cool. There are advantages to different speed for heat/cool but it also makes a difference if the equipment is designed for it. The point is Trane ECM's can do a lot of things but you need to know what you want to end up with before you start connecting wires. There are some Trane systems that you don't connect to O others you do and both run the same CFM for heat/cool. Other systems you select what speed you want for heat/cool. So many options but you need to know what you need for the system to work properly.

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  18. #55
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    I looked over some literature again, and it appears it is correct that O terminal at the airhandler does select heating or cooling airflow based on whether or not it receives 24VAC, so my bad.

    The thing is if you actually look at Tranes airflow charts for that TEM6 airhandler when paired with a 3 ton unit, the correct dipswitch settings produce a less than 50CFM difference on Low, Normal, or High dipswitch settings for each matching setting on heating vs cooing. This is making a mountain out of a mole hill and way overcomplicating this install. I personally would either pick whether I wanted cooling or heating airflows and wire 24vac from R or not. No screwing around with relays etc.

    Also, as mentioned, this airhandler comes with a TXV. I see no EEV options listed.

    TEM6 product data.pdf

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  20. #56
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    If there is such a minimal difference between AC & heating mode then it might just be the difference between a wet coil & a dry coil & have nothing to do with whether or not "O" is activated.
    Gary
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    http://www.oceanhvac.com
    The best things in life are free but not everyone is willing to pay the price.

  21. #57
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    You can get a bigger difference with BK.

  22. #58
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    Thread Starter
    Quote Originally Posted by BNME8EZ View Post
    I am still waiting to find out what he wants to accomplish.

    Looking to do 2 stage.


    and yes it has a TXV

  23. #59
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    Quote Originally Posted by brainsboy View Post
    Looking to do 2 stage.


    and yes it has a TXV
    So first stage compressor second stage heat strips ?

  24. #60
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    Thread Starter
    yes

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