Our Potterton Prima B is controlled by a Randall 4033 Programmer which must be at least 15 years old. The boiler is about 12 years old.
We always run the boiler in Timer mode. We have suddenly noticed that there is a pump noise when the timer is in the Off part of its cycle.
We have tried switching bewteen Timed and On mode and this seems to make the noise go away.
Does this indicate a problem with the controller? If so, what is the cheapest way to fix it? My wife and I have both been made redundant recently so cannot afford expensive repairs.

Jim McCarrick, March 2009

Thanks Bert, can you tell me where I can find the zone valve and roughly what size it is? Is it in the lower compartment or the upper one?

Jim McCarrick, March 2009

the boiler has a pump overrun thermostat which keeps the pump on after demand has finished these can fail,first i would check the zone valve or valves are not sticking as this is the most common cause,move the lever on the valve a few times and see if the pump stops running

bert, March 2009