F01 indicates that one of the safety interlock switches present in the unit has tripped. There are several interlock switches that could possibly trip and cause this error. The following switches are installed standard equipment in all boilers.
1. Flue ECO – Trips if the flue temperature is excessive. This switch has to be manually reset.
2. Blocked vent pressure switch (BVPS) – This switch trips if there is excessive pressure in the flue and automatically resets.
3. (EL-299 / 301 / 399 models ONLY) Boiler module front temperature switch - Trips if there is excessive heat on the front of the heat exchanger.
4. Optional - The UL 353 Low Water Cutoff (LWCO) may be installed on the boiler. This device trips if the water level in the boiler is low. This switch must be manually reset.
1. Determine if the boiler has an optional UL 353 LWCO. If so, check if the indicator light shows that the LWCO has tripped.
2. If the LWCO has tripped, restore proper water level. Then manually reset the switch and boiler.
3. If there is no LWCO or the indicator light is not illuminated on the LWCO, use an ohmmeter to test each of the standard switches one at a time. Turn the power off to the boiler and disconnect the switch to be tested from the boiler to determine which one has tripped. After finding the tripped switch investigate the cause of the fault based on the purpose of the switch. NOTE: The common reasons for temperature switches to trip are a) low water flow through the boiler, or b) poor heat transfer from the water to the load.
4. If no switches are tripped, push RESET on the boiler. If the boiler tries to ignite or ignites and only runs for a short time and the F01 code returns, investigate the flue for blockage.
