I have a thermostat that calls for heat but nothing happens. I have tested voltage at the thermostat, there is voltage at the furnace where stat wire make first connection. There is no voltage at the gas valve. I am losing it somewhere between.
The normal operation should be, call for heat, exhaust fan starts up, electronic igniter sparks, pilot lites, burner ignites and fan kicks in. I get nothing. No attempt to do anything. Please help with your expertise. Sheldon

Set the thermostat for "Heat" & turn it up well above room temperature. Measure voltage at the furnace between R & W low voltage terminals. If you get 24v, there is no power getting to the furnace via the W (heat) terminal. You probably have a bad stat or wire.

Set the thermostat for "Heat" & turn it up well above room temperature. Measure voltage at the furnace between R & W low voltage terminals. If you get 24v, there is no power
getting to the furnace via the W (heat) terminal. You probably have a bad stat or wire.

Your right I changed out the stat and I was up and running. Thanks for your time

Glad to help & glad it was that easy, most are not.