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Wiring a 4 zone boiler w/o a common wire

Dakshack
Community Member

I have a 4 zone oil fired boiler. The wiring is 2 wire, R / W with no C terminal  on the switching relay.

1.     Do I need 1 nest connect for each thermostat?

2.     Where do I connect the C wire from the nest connect?

7 REPLIES 7

laurentbourg
Silver Product Expert
Silver Product Expert

Is your oil boiler currently controlled by 4 different thermostats, one for each zone, located at different places in your house? If so then yes you will need a Nest thermostat per zone to replace each of your thermostats. You should not need a C wire for the Nest 2nd or 3rd generation, I have not test the E or 2020 without a C wire. 

My system is 3 zone valves older system with no circuit board to attach Honeywell RA832A. I understand that i will nee (3) Nest to control .  I cant figure where to hook up C wire furnace. There is a transformer on the 832A? or do I have to pull power from zone valve. or is the C wire being used as a ground? thanks again new to this

EC88
Community Member

I have the exact same issue… A 3 zone oil burner with no terminal on the boiler control panel to connect the C wire. I do have an extra wire so where/what do I connect it to…?

Thekideo
Community Member

I've heard you could use white wire off of transformer as C wire. I also tried the Nest power connect but no luck with that either.

EC88
Community Member

Thanks… Have you tried that solution?

EC88
Community Member

Hey... Just wanted to let you know that I took the spare wire in my cable connected it to C on the nest and connected the other end to the White terminal of my 24VAC transformer. After restarting the Nest it came back without the error message and is now working fine.

Thekideo
Community Member

Cool. I'll double check mine