www.hvactechgroup.com - forums

HVAC Forums => HVAC Help => Topic started by: rovafa2002 on June 14, 2023, 10:28:43 AM

Title: Replacing 80's Thermostat 7.5v?
Post by: rovafa2002 on June 14, 2023, 10:28:43 AM
Hi everyone,

Nice to e-meet you!. I am trying to upgrade my baseboard heaters thermostats upstairs in a house from 87. These thermostat probably were installed when the house was built.

What are my options? I get 12.9v in DC but if I switch to AC I get 7.3v. I tried a new 24v one but it didn't work of course. I am somewhat handy but on basic electric stuff, I am assuming there is a relay somewhere but maybe you know of a nicer Thermostat model that could work for this application just using the two wires.

Thanks in advance!
Title: Re: Replacing 80's Thermostat 7.5v?
Post by: Hgye on June 15, 2023, 02:36:45 PM
Have you tried a battery operated thermostat?
Title: Re: Replacing 80's Thermostat 7.5v?
Post by: Admin on June 16, 2023, 09:39:33 AM
You will have to trace those low voltage wires and see what they connect to.  There should be a transformer that will tell us the output voltage and I would measure the voltage off of the transformer itself.  It's probably 24V AC but your measuring 13V because of a grounding issue. The transformer common may not be grounded.
Title: Re: Replacing 80's Thermostat 7.5v?
Post by: rovafa2002 on June 22, 2023, 11:01:57 AM
Thanks for the replies! As for testing with a battery operated one I did but it doesn't trigger the heat.

Also regarding the grounding issue I doubt it since I get the exact same issue in three different bedrooms.

Any other thing that might be happening?