Marvelous - gives me something else to try tomorrow - thank you.
incidentally to the first replier is there something that can be put into the boiler re hard water as it is a particular problem where i live?
Good people out there some advice please.
Ravenheat rsf100et been installed for approx 4 yrs - no problems. Suddenly dhw cycling on / off. [ch working just fine]
Dhw temp set midway.
Get manual out and follow instructions - switch to hot water only.
Take cover off and watch boiler flame...