Hi there. There is a tricky thing in my boiler. I was observing that my heaters are hot and the temperature is much above which is set on regulator. I took a closer look at what I discover, when boiler shows "t" (pre heating) in fact it heats no hot water but central heating!!!!! God knows when and how long. I'll call the serviceman but maybe it is something easy to fix. Any idea?

Piotr, January 2014

Hi Again
You are right. After cleaning the divert valve all starts working properly but now again heats central instead a hot water, so will buy new valve. I'm from Poland so that is a little delay with delivery infortunately. Also new problem occur it shows DHW thermistor malfunction, so should I replace both of them some time? Thanks for help.

Piotr, January 2014

from your description the divertor valve still seems stiff

i would personally remove & fit a new one

this is a job for a qualified gas engineer

you are not qualified to do this job but at least you now know what the problem is & which part needs replacing

you just have to shop around for a reasonable quote

Q, January 2014

I did as you advice. The head looks like working. I see that the shaft of the valve was stuck and needed a lot of force to move. So I did push and pull few times adn use penetrating grease to make it work. Now all looks operational but stil the problem persist. Boiler is preheating "t" and it heats a central heating instead. Maybe that valve is completely stucked inside? I do not know but something busted iside? Hmm, now I'm little confused. Any ideas?

Piotr, January 2014

divertor valve 174200
sticking or seized
repair or replace

http://www.ebay.co.uk/itm/ideal-isar-diverter-valve-cartridge-repair-kit-part-no-174200-original-/280753479627

Q, January 2014