How can I determine the voltage of my HVAC thermostat?

I just purchased a 24 volt programable thermostat and plan to replace my current one. Is there a way to determine if this 24 volt thermostat will work on my system?How can I determine the voltage of my HVAC thermostat?You determine that with a volt meter or by looking at the transformer that supplies the power. It is almost the universal voltage in the US. You might get the model number of the the one that is in place and check with the manufacturer for it's specifications. Just a tip. Replacing thermostats is not a slam dunk.How can I determine the voltage of my HVAC thermostat?Look for a specification plate or tag on either the hvac control box or the old thermostat - short of that, use a voltmeter and carefully check the wires into your old thermostat. Don't assume it's 24 volts.How can I determine the voltage of my HVAC thermostat?I can't remember seeing anything other than a 24vac thermostat in an HVAC domestic installation. Thermostat's are easy to install.



Turn off power to furnace. Remove the old thermostat, making note of which color of the four or five wires are connected to which letter on the thermostat base. If you matched the correct color of wire to each letter on the new base it should be fine.



If there is a hole in the wall behind the thermostat that air can come out of, be sure to plug the hole.



If you have a solid state thermostat (one with out a mercury bulb in it) you don't have to worry about it being level. Other wise level the base of the thermostat before mounting the thermostat.



The only way to know for sure is to check for voltage at the thermostat with a meter, thermostat set to off, check between wires (from red to others wires if the color code has been followed). You should read 24 to 26 volts ac.



good luckHow can I determine the voltage of my HVAC thermostat?three types of thermostats

type 1 the most common is a 24 volt thermostat has realy small wire like that of a telephone cable



type 2 110v thermostat has big wiring like that of the house



type 3 millivolt thermostat usually 750mv



type 2 and 3 are not common in a home unless it has a boiler

type one 24 volt is the most common



there will a transformer on the furnace where the two wire are connected to or on the circuit board it will say 24v where the two wires go in for ac as well it will be five wire



follow the wiring diagram in the box and you cant go wrong or as you take wired off your old one write down which letter they were connected to and do the same on the new oneHow can I determine the voltage of my HVAC thermostat?look at the wires if they are small red white green then they are low voltage ie 24 volts