Having noticed a few unanswered questions about boilers in The Happy Room, maybe this will fulfill a need.
My own Vaillant boiler needs the heating turned on for the hot water to happen. I'm in denial of course, because I don't want to pay for some chap to come over and (possibly) do something simple for loads o' money. On the the other hand, I just know that on the coldest, darkest day just before Xmas . . .
Ha! You think you got problems! Me boiler is totally fecked, me cowl got blown off off in a hurricane and the rain entered down the flue. Hence, I have no heating at the mo except for a dismal halogen heater.
My hot water is by immesion
Brrr! Shades of a Child's Chistmas in Wales and chucking snowballs at the cats for amusement I think.
Hardy Stock, the Welsh!