Swiftflow 100 died today. Main burner not firing on either DHW or CH. Pilot
+ fan + pump running fine. I havent got the installers instructions that
would allow me to work through the flowchart that Hepworth thoughtfully
include. Before shelling out 115 for a new Gas Valve are there any overheat
or flow sensors that would prevent the gas valve operating on both HW & CH ?

Neil