Im hoping someone can explain to me why we keep getting the F23 error message and how we can prevent it happening again.
We have a combi boiler (downstairs) and a hot water cylinder (upstairs). As far as I understand it the combi heats the hot tap water downstairs directly, all the rads in the house, the underfloor heating we have in the upstairs bathrooms and the hot water cylinder upstairs.
A month ago we got the F23 error. A vaillant engineer said it was because we have the rads upstairs on low which is causing a significant temp diff between the combi flow and return which causes f23. He made some adjustments to the boiler and said it shouldnt happen again.
Yesterday we decided to test the piped underfloor heating we have in the upstairs bathrooms. Weve never used it before. The previous owner of the house said it may take 1-2 days to heat the floor tiles up which sounds like a long time to me but i know nothing about UFH. After leaving it on for 24h the tiles were still stone cold and the combi fell over with the f23 again.
Weve turned the UFH stat right down and darent try using it again!
So I guess its 2 questions really...
1) Anyone know whats going on with the combi and how we can stop f23?
2) Can someone explain my UFH? How come the tiles were still cold after 24h? When we turn the stat up the boiler fires up but it wasnt firing for that whole 24h period, it kept stopping and starting periodically. Also, surely the UFH wouldnt be running during the night when our heating is turned off? The previous owner said the UFH is on the same circuit as the towel rads but the towel rads have always worked fine and come on with the room rads when the UFH stat is turned right down. (ps the previous owner built this house).
We are confused