When troubleshooting a residential heating system, the technician reads 24 volts across R and W on the furnace low-voltage terminal strip with the thermostat set to call for heating. What would be the most likely problem?
A) defective gas valve
B) defective transformer
C) blown high-voltage fuse
D) defective thermostat

Question

Quizplus · Accepted Answer

The 24 volts across R and W on the low-voltage terminal strip indicates that the thermostat is calling for heat and the signal is reaching the furnace. However, if the furnace is not responding, then the thermostat may be defective and not properly communicating with the furnace. The other options (defective gas valve, defective transformer, blown high-voltage fuse) would typically result in no voltage at all on the low-voltage terminal strip, rather than voltage being present but the furnace not responding.

When Troubleshooting a Residential Heating System, the Technician Reads 24