My 4 year old Valiant boiler keeps cutting in and out when heating water for the taps and shower in the house, which means we are getting warm water one minute and cold/ luke warm the next ! We have in the past few months recently spent £900 having a power flush and getting the main heat exchanger replaced which worked fine for about 3-4 months but it is doing the same thing now as before. Very odd as central heating works perfectly. A fault code of F.22 comes up sometimes. Can anyone help with what it might be ??

Just had enough with it now and considering just giving up with it and paying out for a new Worcester boiler !!

Em W, November 2008

diverter valve might need replacing

haq, March 2009

It is most definately the domestic heat exchnager at fault (also known as the plate-to plate). In my experience - 32 years - a power flush will not clean this component adequately.

Aarovic, December 2008

Hi got the paperwork with me today, the boiler is the Valiant turbomax 824e model. They also checked the pump and it was fine, he checked everything to do with the fault code but everything was fine related F.22 fault code.

I think the domestic heat exchanger was also cleaned when the powerflush was done and the new main heat exchanger was replaced. They also put some centreal heating inhibitor in the system when they had finished is this magnaclean ?

Central heating works perfect, just the boiler keeps cutting in and out when you turn the hot water taps or shower on, pretty annoying as I'm 6 months pregnant and couls really do with a hot shower that works all the time !

I have been searching the net this morning, could the diverter valve be causing, reading back in the history of the boiler the people that had the house before us had this replaced about 3 times by Valiant ? !

Em, November 2008

? ecoMAX
F.22 = No water in system
Low water or no water in appliance
Pump defective
Pump lead defective

a, November 2008

was the domestic heat exchanger cleaned out when power flushed? if not then it will need changing waterways blocked.. then have magnaclean fitted to return heating pipe it will stop it happening again

alan, November 2008