Arrived on site, for no heat. Homeowner has been in the home for two years. Homeowner stated blower motor was running Hear the gas running. I began by setting the downstairs thermostat to heat. Upon reviewing the furnace, I found it was not calling for heat on the zone board. I tested the heat directly from the zone board and the furnace completed the heat cycle without issue. I then tested heat on the upstairs thermostat and it also completed the heating cycle without issue. I then wired R and W together on the downstairs thermostat and found that the heating cycle completed without issue leading me to believe that the thermostat is not sending a signal for heating. Advise homeowner upstairs heat is working at this time and provided estimates for thermostat replacement and possible warranty. Homeowner elected to try to replace the thermostat himself and
