Can anyone please give me any hints as to what is wrong with this combination valliant boiler that is giving heating but not giving hot water? the hot water is only functional when the heating system is on. 6 new rads were fitted and the system was also flushed. Now contains inhibitor.

David, October 2011

hot water heat exchanger is blocked look like sadin can at back take it out clean with spirit if salt.

ltd, October 2011

thanks for your reply, heating flow from boiler was totally blocked solid so i changed it,cleaned out the system,then added inhibiter filled up to 2br and bled rads then turned on the heating everything was fine hot water was fine,turned off heating and later their was no hot water and the hot water pressure is low from the hot taps,but when i put the heating back on i get hot water pressure from hot taps pick up slightly,it was power flushed prior thats how i found the blocked chf pipe blokecd

David, October 2011

Try without heating, turning two hot taps on, at the same time, if it then comes on, the flow control for hot water is faulty, Other than that, need more info, what exactly happens, what does not happen etc Plus model etc.

SD, October 2011