Burner and pump running when no DHW drawn

[vmaxnick]

Hi all, my old Heatline Capriz plus 24 is playing up, when you draw DHW, it does it's job fine, but when you close the tap, the hot water symbol in the LCD display keeps flashing and the burner switches off but the pump and flue keep going for a bit, as you'd expect, but after 30 seconds or so, the burner fires again. This continues until you turn the boiler off manually. If you then draw COLD water, it's hot until it's drawn enough through to cool itself. We use the central heating intermitently as we have a log burner. Had various issues with it over the last 2 years where I replaced expansion tank, heat exchanger, PCB pressure guage and LCD display. I had an F32 fault last week (Flue pressure) Last night I changed the diverter valve assembly and purged the flue pipes. Everything is working again now DHW and heating, but the problem persists where the boiler isn't shutting down and is heating the cold water. It's a bit of a mystery The burner shuts down when you close the hot tap but the HW display stays flashing and it powers back up. If you reset the boiler, it stays off until you draw DHW then the problem persists until you manually shut it down. Appreciate any advice in advance.

 

[gas112]

it is showing there is a HW demand when no demand so flow switch or sensor attached to it is faulty

 

[vmaxnick]

it is showing there is a HW demand when no demand so flow switch or sensor attached to it is faulty

Thanks, I'm waiting on a new flow impellor and sensor, will report back if that fixes the issue.

 

[vmaxnick]

So, just replaced impellor and sensor, no change. However, I have found the problem; underfloor hot water pipe is leaking. Doh! I've fitted an isolator valve which has cured the issue, now I just have to run a new length of pipe to the bathroom taps.