Baxi Solo WM 30/4 RS No Hot Water

I was called to look at a Baxi Solo WM 30/4 RS which was not working and the lady had ran out of hot water. Immediately I could see that the pilot was not lit and attempted to relight the pilot light. It would not stay lit and being the SS version had an overheat thermostat interrupting the pilot thermocouple at the gas valve. Once I had reset the overheat thermostat I was able to relight the pilot light and the boiler was able to fire for the hot water.

As soon as the main burner came on I could hear that the boiler was unusually noisy and so checked the burner pressure which was as it should be. The pump which was adjacent to the boiler was fairly old and didn't quite sound as if it was running at the correct speed. I replace the pump and refired the system and the boiler was running a lot more quietly and didn't sound so scaled up.

After the boiler ran for about five minutes it started to crash and bang before cutting out on the overheat thermostat. I used my flue and gas analyser to measure the flow and return temperatures to find that the flow temperature was exceeding what it should have been and the boiler thermostat was not cutting off the boiler until the overheat thermostat kicked in. I replaced the Ranco C77P0135 thermostat and the system was working well again.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.