I have noticed over the last few weeks that my Potterton boiler is cycling much more frequently than usual. When it get's near the desired temperature it tends to start up for approx 30 -90 seconds then shuts down for a similar period until it gets to the temp. I have had British Gas out 6 times where they have replaced the pump, room thermostat, boiler thermostat, PCB and some other componenets but I am not sure what they were. I mentioned that I had put Fernox F5 through the system and they have said that this would cause the sytem to work much more efficiently and therefore the cycling will occur at quicker intervals, I am not convinced and the boiler is still switching on & off frequently. Any ideas?

George Day, February 2011

Hi Brian

I tried it but no luck I am afraid it is still switching on and off at very regular intervals, I have turned the pump speed down in an effort to reduce it but again no luck. Any ideas on a faulty component? although there is not really anything left to replace now.

Kind regards

George, February 2011

sometimes it can be the system if you have a small rad near the boiler it will get hot very quickly and the return water is as hot as the flow at start up this doesn't matter as the return from the other rads lowers the temperature later on however it can create a "false" return temperature causing short cycling if this is the case then turn one of the rad valves off and then open 1/4 turn only this should reduce it's effect

brian, February 2011