Replacing a thermostat.

[techs]

I have one of the old fashioned thermostats you can see here:
http://www.homedepot.com/Building-Ma...atalogId=10053

I disassemled it and it just has two wires coming into it.
Can I replace it without cutting the power or turning off the heat in the basement? Or will I electrocute myself or do damage?

Thanks.

 

[Fear No Evil]

I'm pretty sure its low voltage. I've always turned off the electricity to the furnace/AC unit when working on it but I don't think you will kill yourself. Then again, I could be wrong.. sorry I'm of no help.

 

[Mark R]

Turn the power off.

These are often mains voltage, as traditionally, furnaces didn't use any low-voltage circuits. The valves and pumps were all mains powered. The thermostat acted simply as a switch that turned on the gas valve and circulation pumps.

Modern furnaces may use electronic controls, but the mains voltage connections are preserved for compatability (as some thermostats have a small heater inside that comes on when the thermostat is requesting heat - this means that the thermostat shuts off slightly early, and avoids the temperature overshooting as the house continues to warm up due to radiators/pipes/ducts remaining hot).

 

[skull]

Its 24 volts you can't short anything out if its only red and white. Reds power white goes the relay to turn the heat on.

 

[skull]

Turn the power off.

These are often mains voltage, as traditionally, furnaces didn't use any low-voltage circuits. The valves and pumps were all mains powered. The thermostat acted simply as a switch that turned on the gas valve and circulation pumps.

Modern furnaces may use electronic controls, but the mains voltage connections are preserved for compatability (as some thermostats have a small heater inside that comes on when the thermostat is requesting heat - this means that the thermostat shuts off slightly early, and avoids the temperature overshooting as the house continues to warm up due to radiators/pipes/ducts remaining hot).

120v thermostats are really rare. OP if the wires are thick like house wire call a professional. If there thin it should be like I said.