Potterton Combi 8o CH stays on

[DavidHop]

I have a Potterton Combi 80 Boiler that is about 5 yrs old. It worked fine until January when it needed a new control board. About a week ago I tried to get get water and noticed that the boiler had locked out. I reset the boiler and got hot water. The boiler has since locked out 3 more times each time I have reset it and I can get hot water. 2 days ago I noticed that after drawing a sink of hot water the central heating comes on (this despite the fact that the thermostat is set on its lowest setting and the programmer is set to off). The only way to stop the boiler is to switch it to standby after a while (I don't know how long I have only left it over night) you can turn the boiler back on and the heating will not turn on. This problem only seems to occur when a small amount of hot water is needed if I run a bath the problem does not occur. Can any one help?

 

[ChrisR]

SOunds like the domestic hot water flow switch is sticking on. Has cropped up several times on the forum so do a search - same thing happens on a Puma boiler.