Thermostat calls for heat but connected Stelpro baseboard or convector does not warm up

Safety: Turn off power at the breaker before opening any junction boxes or heater covers. Confirm power is off.

Steps to troubleshoot no heat at the heater:

• 1. Confirm thermostat output: With the thermostat calling for heat, measure voltage at the thermostat load terminals (carefully, with power ON). If full line voltage is present, the thermostat is working.
• 2. Check junction box connections: Turn power OFF. Open the heater junction box and inspect wire nuts and connections for loose or burnt wires. Tighten or remake connections as needed.
• 3. Test heater element: With power OFF and wires disconnected, measure resistance across the heater element leads. An infinite reading indicates an open element or tripped internal safety.
• 4. Inspect thermal cutoff: Many Stelpro heaters include a manual-reset thermal cutoff. Look for a small reset button on the heater body and press it if present (power OFF). Clean dust from the heater to improve airflow.
• 5. Check wiring continuity: If the heater tests good, check continuity of the cable between thermostat and heater to ensure there is no break.
• 6. Replace heater or repair wiring: Replace the Stelpro heater if the element is open or the internal safety cannot be reset. Repair or replace any damaged wiring.

Warning: Do not bypass internal heater safety devices. Replace the heater if the safety device has failed.