topic Re: Do I need an Isolating relay? in Nest Thermostats

Do I need an Isolating relay?

AlanPA — Sun, 27 Feb 2022 05:31:08 GMT

HVAC ITEMS, My hardware:

Hyrdro-therm HC-145 boiler for hydroponic baseboard heat ~ 50 years old

24-volt transformer with R, C, W, G terminals

White Rodgers Zone Valves, Mode number 1311-102 times TWO.

One for upstairs heat

One for downstairs heat

Terminal 4 = white wire ---à W1 = “call for heat”. Causes valve to rotate open and furnace to ignite.

Terminal 5 = red wire ------à Rh = power

Terminal 6 = green wire. ---à Y1 = “call to stop heat” and turns furnace off.

Was working fine until put in Nests GA02082-US thermostats in place of upstairs and downstairs Honeywell thermostats.

Now will actuate Call For Heat and system works to warm house.

DOES NOT CALL TO STOP HEAT! No activity to Green wire by Nest Thermostat.

Old functioning Honeywell thermostat had White to W1. Red to Rh. And Green to Y1.

Same wiring used with Nest thermostat.

Getting an N260 Code form Nest, related to needing a “C” wire, which I can handle.

QUESTIONS:

How do I get power to the Green wire to call to stop heat by shutting valve on zone valves?
I see on the internet that people are using an Isolation Relay. But I don’t see a wiring diagram anywhere. How do I wire the isolation relay to the thermostat and the boiler’s zone valves?
Is it possible to program the Nest thermostat to power the green wire to call for stopping the Heating cycle?

Re: Do I need an Isolating relay?

Ryan_G — Sun, 06 Mar 2022 22:11:44 GMT

Hi AlanPA,

Thanks for reaching out and we're sorry for the delay.

With this kind of setup, it is recommended for a HVAC tech to inspect and they will check further if a relay is needed for your multi zone system.

Also, let's stick with the wiring setup and go to settings > equipment then select the right heat type and source from your Nest Thermostat.

I hope it helps.

Best regards,

Ryan

Re: Do I need an Isolating relay?

Ryan_G — Wed, 09 Mar 2022 22:53:58 GMT

Hey AlanPA,

I just wanted to follow up and see if you're still in need of help? Please let me know, as I would be happy to answer any questions you may have.

Best regards,

Ryan

Re: Do I need an Isolating relay?

Ryan_G — Sat, 12 Mar 2022 22:59:05 GMT

Hey there,

Just wanted to jump in here to check to make sure that you saw our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Have a great day.

Best regards,

Ryan

Re: Do I need an Isolating relay?

Ryan_G — Sun, 13 Mar 2022 23:52:42 GMT

Hey folks,

It looks like we haven't heard back from anyone so I'm going to go ahead and lock the thread. If you have any further questions or concerns, feel free to create a new thread.

Have a great day.

Best regards,

Ryan