I am putting in a honeywell tstat TH8110U, and have two wires coming out the wall (white and black). Is the white the heat relay?

Unless your unit is a heat only thermostat, I would call on the "services" of a hvac tech. typically there are multiple wires (whi, yel, grn, red, blu, etc) going to the thermostat, which, depending on what weekend warrior installed the earlier thermostat could be connected to anything... Check the thermostat instructions... also, if your diy instructions don't make sense, and your not familiar with electricity and you can't read a schematic, don't operation... looks like you may be trying to fit a circular tube into a square hole...

P2E :confused:


I am putting in a honeywell tstat TH8110U, and have two wires coming out the wall (white and black). Is the white the heat relay?

I am putting in a honeywell tstat TH8110U, and have two wires coming out the wall (white and black). Is the white the heat relay?
... to get back on-line and answer your questions.

On most systems, the hot wire from the transformer connects to the R terminal at the stat, and a white wire runs from the W terminal to the relay or solenoid controlling the heat.

With only a 2 wire system, it would still work if the conventions weren't followed.

On most systems, the hot wire from the transformer connects to the R terminal at the stat, and a white wire runs from the W terminal to the relay or solenoid controlling the heat.

With only a 2 wire system, it would still work if the conventions weren't followed.

Labman, Thanks for the help, as it turned out I had it wired correctly but nice to be sure.