My PROTHERM 80E works fine on C.H but does not give hot water. [it used to but stopped]. CH Plumber turned power off and on and it worked briefly but stopped after an hour and will not give hot water. F1 shows briefly when power turned back on but then goes off and normal (temp) display shows.
CH works OK. HW display light does not come on (CH light stays on). No pilot light but boiler lights fine when CH demand on.

Is there a simple fix? Control switch/valve?

I do not have a manual

Will, August 2007

check that your diverter valve is working

zola, August 2007