2 thermostats in parallel - hybrid hydronic

SiZim

Hi

I have a steam boiler - which had a hydronic baseboard zone added before we bought the house. The hydronic zone is in the addition on the ground floor and the steam heats the front of the house and the upstairs so we want to make it a two zone system. The plumber had put in a relay controlling the hydronics with an aquastat and the circulator controlled from it. The red and white wires from the relay (I presume) are wired in parallel with the main house thermostat... so if either stat calls for heat the boiler will fire.

I just replaced the old stat for the main house with a Honeywell EIM and put a FocusPro wireless upstairs so that things will work better as a two zone system as before both stats were on the ground floor. But it made me think - is it safe to have these wired in parallel like this?

Right now the hydronic zone is controlled by a T87 (non mercury) but sometime I want to have a programmable stat there instead. I read some articles about anticipator circuits causing a problem but I am not sure if that is the case with these newer programmable models. Any issues in parallel like I currently have it also? Would not want to blow the new EIM.

Thanks

Si

icesailor

Parallel Thoughts:

Use Isolation relays and blow up to your hearts content.



Something is missing.

JohnNY

No problem

There's nothing wrong with wiring the two thermostats in parallel using any of the devices you're describing.



Go for it.