I know there are lots of posts on these old boilers, but none seem to quite match the problem I'm having, unless I haven't looked carefully enough. Informed advice gratefully received!
System is: Potterton Suprima 50 boiler and Heatrae Sadia megaflo unvented cylinder.
Had various problems over the years, but this is what is happening at moment.
Following the last service not so long ago, had problems with the pump running and the boiler firing occasionally even when the controller for hw & ch were turned off. Problem seemed to resolve after a couple of days and cancelled engineer visit; found that when the boiler was working, the pump was pretty much always on (it would stop for a couple of seconds and then start going again, coupled with the boiler lights indicating (briefly) "no external call for heat" and then very quickly changing to "boiler temperature control satisfied"). Lived with it for a bit, but the problem of the boiler working when the controller is off has re-emerged, so the pump is always on, with brief stops of seconds, and the boiler is occasionally firing when the timed controls are off. The boiler does still seem to respond to the controller, i.e. only firing properly and in a sustained way when that is on, but it won't shut down completely ( to the state where the pump is off and the boiler light indicates no external call for heat) . Had to turn everything off at the mains to stop it.
Called out engineer and he changed PCB and twiddled with thermostat setting on the cylinder, room thermostat etc. He tested things out, seemed very good intially, but after he left and the timer was due to go off, the pump just kept running as before and boiler was indicating that the boiler temperature control was satisfied, wasn't changing to the no external call for heat. So, the problem is still there.
One difference: When you turn the temperature dial to off, everything does as it is supposed to. Pump doesn't run, light indicates no external call for heat. Turn it on even a smidgen and it fires up regardless of the timer for CH & HW being off. Drained the tank of it's hot water and left it for a few hours. Turned back on, fires up - hot water builds up again, central heating nice and warm, but when the timer is turned off, pump keeps going again etc.
So, engineer booked; again. Another day off work. What's happening with the bloody thing? Is it something to do with the pump? Motorised valves? The cylinder thermostat seems to work fine. Water temp matches the setting on the dial when changed.
The engineers that come out on my service plan either fob me off or just change the PCB, which does not seem to address things. It's not my area of expertise, so any help gratefully received. Thanks!
System is: Potterton Suprima 50 boiler and Heatrae Sadia megaflo unvented cylinder.
Had various problems over the years, but this is what is happening at moment.
Following the last service not so long ago, had problems with the pump running and the boiler firing occasionally even when the controller for hw & ch were turned off. Problem seemed to resolve after a couple of days and cancelled engineer visit; found that when the boiler was working, the pump was pretty much always on (it would stop for a couple of seconds and then start going again, coupled with the boiler lights indicating (briefly) "no external call for heat" and then very quickly changing to "boiler temperature control satisfied"). Lived with it for a bit, but the problem of the boiler working when the controller is off has re-emerged, so the pump is always on, with brief stops of seconds, and the boiler is occasionally firing when the timed controls are off. The boiler does still seem to respond to the controller, i.e. only firing properly and in a sustained way when that is on, but it won't shut down completely ( to the state where the pump is off and the boiler light indicates no external call for heat) . Had to turn everything off at the mains to stop it.
Called out engineer and he changed PCB and twiddled with thermostat setting on the cylinder, room thermostat etc. He tested things out, seemed very good intially, but after he left and the timer was due to go off, the pump just kept running as before and boiler was indicating that the boiler temperature control was satisfied, wasn't changing to the no external call for heat. So, the problem is still there.
One difference: When you turn the temperature dial to off, everything does as it is supposed to. Pump doesn't run, light indicates no external call for heat. Turn it on even a smidgen and it fires up regardless of the timer for CH & HW being off. Drained the tank of it's hot water and left it for a few hours. Turned back on, fires up - hot water builds up again, central heating nice and warm, but when the timer is turned off, pump keeps going again etc.
So, engineer booked; again. Another day off work. What's happening with the bloody thing? Is it something to do with the pump? Motorised valves? The cylinder thermostat seems to work fine. Water temp matches the setting on the dial when changed.
The engineers that come out on my service plan either fob me off or just change the PCB, which does not seem to address things. It's not my area of expertise, so any help gratefully received. Thanks!
.
