NCM-300 w/ecobee tstats

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tobybowen
Posts: 1
Joined: Thu Nov 19, 2020 2:48 pm

NCM-300 w/ecobee tstats

Post by tobybowen »

I have a 2-zone, single stage gas furnace & outside A/C unit system. About 2 years ago I installed an ecobee 4 on the main floor (zone 1) with out issue and maintained the standard tstat in zone 2. Recently upgraded to ecobee 3 for zone 2, and now getting an issue when calling for heat in zone 2.

Ecobee tech seems to think we have a voltage issue causing the voltage to drop and only allow the furnace to run for about 1 min before shutting down. They recommended installing a transformer to supply additional voltage and see if that fixes the short run issue with the furnace.

My question is, can I wire the transformer into the zone 2 tstat C and Rc terminals on the board rather than at the tstat in the wall? This would be a cleaner install without having to run an additional wire inside a finished wall.

Old tstat wiring (IMG_4262), new tstat wiring (IMG_4261) and zone board wiring pictures (IMG_4268) attached
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John B.
Posts: 20
Joined: Fri Mar 13, 2009 8:57 am

Re: NCM-300 w/ecobee tstats

Post by John B. »

Sir,

That does'nt make any sense unless your NCM300 is being powered from the Furnace transformer, rather than a dedicated transformer. According to your pictures, each thermostat already has a 24v common wire.

Please don't do anything until you call and talk to us!...Do you have a voltmeter?...we'll need it.

John
John Brown :geek:
John B.
Posts: 20
Joined: Fri Mar 13, 2009 8:57 am

Re: NCM-300 w/ecobee tstats

Post by John B. »

By the way...it appears that you are missing a jumper from Rc to Rh on the Ecobee sub-base with the bubble level.

John
John Brown :geek:
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