Circulator wiring with Taco SR504 switching relay

danaturcotte

Hello, let me thank you in advance for your information and time. This is my first post so bare with me. I have a unconventional out door wood boiler with radiant heat. 3 zones for house and one zone for pool. My question is it possible to have the circulator at the wood boiler only come on if one or multiple zones circulators come on from the thermostat for such zone? If so how would I wire it to do so using a taco sr504 switching relay? Reason why I'm asking is I have a main cir. on a large diameter loop from the wood boiler into the house that circulates 24/7 then the zone circulators branch off of that loop I would like it to only circulate when a zone or multiple zones call for heat

Dave H_2

You cannot make it work with the exisitng control you have. You do need to add either a single zone relay (SR501) or a newer SR504-exp.

Using the existing and a new 501, you would wire 120v and the boiler pump to it.

From the the relay you already have, 2-wire t-stat wire would run from the bottom right terminal (isolated end switch) to TT at the top of the SR501.

If you were to get the new SR504-exp, it would have the terminal for Primary Pump and its function is already in the controller.

danaturcotte

Thank you Dave H_2 , I appreciate the information. I will look into the SR504-exp

bjohnhy

I don't remember details, but I've come across a system where the main system circulator (like you describe) is fed with the 120vac hot wire going through this isolated end switch. That switch closes when any one of the zones call.

Was that not an appropriate set up?