Make: All
Model or Series: All
Type: Gas Boiler
Problem Description: No heat
Observed Symptoms: All thermostats calling for heat but pump doesn't run & burners don't ignite.
Solution: Found power to valves but no closure of the end switches to activate boiler. Replaced valve actuators.
Additional Information: L8148 Aquastat Relay, Vent Damper
- "TV" terminal from Aquastat Relay wires in parallel through actuator end switches back to "T" terminal to start pump and enable boiler through water temperature controller.
- Check for 24Vac across actuator motor terminals to make sure zone thermostats are calling for heat.
- Opening of any zone valve should close end switch and activate boiler.
- If necessary, place a jumper between "TV" and "T" to test Aquastat Relay and see if circulating pump starts.
- Vent damper must prove open before energizing ignition.