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zone valve question

cf Member Posts: 3
Have a taco 3 wire valve on geothermal system would like to replace with honeywell v8043

wondered if anyone had tips on the wiring to make it easy.

any response greatly appreciated.


  • HDE
    HDE Member Posts: 225

    3-wire powers the valve open and closed. The H/W is spring closed, so now you only use 2 wires to power it open.

    Other factors may be involved though such as a signal from the 3 wire must be changed to end switch operation from the 2-wire valve head.
  • billtwocase
    billtwocase Member Posts: 2,385
    are all 3 terminals used on the Taco?

    Easy wiring. Your #1 on your taco will become TH on the H/W, #2 on the taco will become TR and jump it to the end switch terminal above it. #3 on the taco will be the other end switch terminal. The bottom far left terminal on the Honeywell is nothing, and not used. If there are only 2 wires on your Taco, the end switch will not have wires connected to it. Only TH and TR will be used, like an EK. Good luck
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    That is not a power open/power close valve.

    With the Taco valve You aply power to two of the terminals and this opens the valve - the third wire feeds power back to the heat pump to start the compressor.

    The Honeywell valve may not have enough closing force to stop the water flow.

    I would replace it with another TACO.
  • cf
    cf Member Posts: 3
    thanks for the replies

    plumbed in the hw and you were right won't close all the way. will be talking to the salesman tomorrow. and yes the taco uses all 3 wires and thanks for the how to on the wiring.
  • RJ_4
    RJ_4 Member Posts: 484
    system pressure

    I believe the old taco valves were a slow opening globe valve design ( heat motor ) I believe the mh valve use a spring and rubber ball device, I would check both manufacts. for pressure drop and flow data   There have been water hammer problems in the past if the wrong valve is installed.  I agree with Steve.
  • cf
    cf Member Posts: 3
    Thanks for the advice

    Where is a good place to buy the Taco valve.
  • RJ_4
    RJ_4 Member Posts: 484

    most hvac supply houses should stock them  Taco is a large manufact. of valves pumps etc
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