# Two Relays On One Thermostat?



## Sawyer (Jan 4, 2011)

I have a thermostat to control the circulator in my workshop. I want to share this thermostat with a Taco SR503 switching relay on zone one to control a pump in the boiler room so both pumps come on at the same time. I donâ€™t believe I can connect both thermostat wires to the single thermostat because I am worried about the two different transformers conflicting. Am I correct?

Is there a switch I could connect to the 120v output or 24 volt on the Honeywell relay (like a normally open) that would energize when the thermostat activates the Honeywell Relay closing a switch to activate the Taco?

Am I complicating this?


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## Sawyer (Jan 4, 2011)

Would the RIBU1C work for this application? http://www.functionaldevices.com/pdf/datasheets/RIBU1C.pdf


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## ewdudley (Jan 4, 2011)

Sawyer said:
			
		

> Would the RIBU1C work for this application? http://www.functionaldevices.com/pdf/datasheets/RIBU1C.pdf



You've got it.  The RIBs are nice because that have the option of a 120VAC or 24VAC relay coil energization inputs.  (Just be sure you get the 120VAC/24VAC version.)  The contacts a may be a little iffy for a inductive load, even a small one like a circulator, but it should still last many years.

--ewd


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## Sawyer (Jan 4, 2011)

ewdudley said:
			
		

> Sawyer said:
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Thanks! I will get one and give it a try.


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## Sawyer (Jan 5, 2011)

Fortunately I was able to disconnect the thermostat from the Honeywell relay and feed that to the Taco 503. I then came off the X1, X2, terminals and connected those leads back to the Honeywell. The relay works great, both pumps come on simultaneously when the thermostat calls for heat.

I will still use a RIB on the pump in the house to close contact when the pump in the house runs.


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## BurnBabyBurn (Aug 10, 2011)

I have been considering doing the same thing with my garage and home thermostats. How is the switching relay working out for you it seemed there was some cause for worry about the relay coil energization inputs ? Since it has been a few months I was hoping I could be lucky enough to gain some wisdom from your experience. Thanks for any information and I appreciate any reply.


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## Sawyer (Aug 11, 2011)

BurnBabyBurn said:
			
		

> I have been considering doing the same thing with my garage and home thermostats. How is the switching relay working out for you it seemed there was some cause for worry about the relay coil energization inputs ? Since it has been a few months I was hoping I could be lucky enough to gain some wisdom from your experience. Thanks for any information and I appreciate any reply.



It works great.

I unhooked the thermostat wire from the Honeywell relay that controls the gas boiler and ran it to the Taco thermostat connection that controls my pumps at the Garn. I then hooked the thermostat wires on the Honeywell relay to terminals X1 & X2 on the Taco. Everything sequences properly.


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