Nest E (3) and Nest 3rd Gen (1)

Old 11-18-19, 08:02 PM
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Nest E (3) and Nest 3rd Gen (1)

I have a Burnham V-74-T furnace, 4 zone, 3 just heat and 1 does heat and AC. Installed 4 Nest thermostats and my furnace is clicking rapidly. Appears I need a common wire for power. Do I need to add a common wire for each thermostat? And how do I do this?
What additional info can I provide for assistance?


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Last edited by PJmax; 11-19-19 at 05:57 PM. Reason: added pic from link
Old 11-19-19, 05:12 AM
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Hi, each stat will need a common C conductor to do the install correctly, post some pics of your current Stat wiring and also the control center of the furnace.
Old 11-19-19, 06:01 PM
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Welcome to the forums.

You've got some issues. That old Argo panel was not sized to run multiple electronic thermostats. It only has a 15va transformer to power the entire board and the relays. It will not power your wifi stats properly.

Technically you'd need to use a another 24vAC transformer to power the nests.
The nest on the heat and A/C should be ok. That thermostat needs to get its C from the A/C.

How many wires between the thermostats and that Argo board ?
You're going to need at least three wires.

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