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Can I Safely Jump Inputs on Taco 6 Zone Relay

I had a second floor addition done this year and added 2 new HVAC systems supplying both AC and heat for the first and second floors, but I never removed the old radiators on the first floor and now I would like to use them along with the new heating system.

I added in a hot water tank and 2 more zones and I added a Taco SR506-4 switching relay and right now it is set up like this:

Zone 1 - Circulator pump for old hot water radiators (wires still connected from old thermostat but no longer used - thermostat disconnected)
Zone 2 - New circulator pump supplying hot water to first floor air handler
Zone 3 - New circulator pump supplying hot water to second floor air handler
Zone 6 - Indirect hot water tank (not being used yet)

What I would like to do is jump zone 1 and zone 2 together so the first floor thermostat energizes both zones together and brings in the circulator pump for the hot air heat and also the circulator for the radiators. I wasn't sure if I could just jump the R to R and W to W between zone 1 and 2, or if there is another way to do it. I have found many diagrams online but not an actual schematic for the Taco relay box showing how the inputs are wired to the relays. I know each inputs of the relay box puts out 24VAC, but just not sure of the best way to connect 2 of them together.

If anyone has any ideas or has an actual schematic for the SR506-4 box let me know. Any info would be appreciated.


  • Zman
    Zman Member Posts: 7,572
    It should work like you suggest.
    Give it a go..
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • happy4ya
    happy4ya Member Posts: 2

    I went for it and it worked fine. The only problem now is the recovery on the air heat is so quick the thermostat shuts off before the radiators get a chance to get good and hot. Gotta play with the thermostat differential and see if I can stretch the on time a little longer.
    HVACNUT Member Posts: 5,855
    edited December 2017
    Why do you want to run the air and rads together? Are there rooms w/o rads?
    What operates the fan on a heat call? If it's a clamp-on aquastat, you could lower the cut in and and raise the differential.
    Is the 2nd floor A/H in the attic? Glycol?