Problem with failed Oil Potterton Statesman Flowsure + Combi boiler

oliveoil54

Hello, Can anyone help, my husband is at his wits end!



Our boiler is an Oil Potterton Statesman Flowsure + Combi boiler.
A few days ago woke up to cold radiators Checked boiler and boiler temperature gauge was showing boiler at 90deg (it usually runs at 65-70).



When I moved the diverter valve arm to manual position, radiators got hot but boiler was still controlling at 90 deg. When valve arm was moved back to auto, the radiators went cold eventually and boiler was still at 90 deg. The pump appears to be working ok. The Burner cycles much more frequently than normal to keep everything at 90deg.



The Boiler temp control knob didn't have any control of the boiler in this condition so I replaced the boiler thermostat but this hasn't changed anything. I'm wondering if some other thermostat has failed to cause the boiler to drive to 90 deg.(Heatstore stat or tank limit stat?).



I replaced the diverter valve actuator about 3 years ago, so I would be surprised if that had gone again.



But something has changed to make the boiler run hotter.



We are not in a position to be able to afford a new boiler.

Would be really grateful for any help or advice.

Datcher

Hi,

I too am suffering from a similiar problem with the same model of boiler.

The symptoms I am seeing are:

No hot water in the morning. Boiler temp around 90 deg which may or may not result in the overheat indicator being illuminated.

To get around the problem I switch off the boiler at the mains and let cool down. Once the temp is below 88 deg (limit stat setting - I think) I switch it back on and reset the overheat if necessary. The boiler seems to operate ok for the day but same thing the next morning. As you say, the boiler control has no affect.

If my memory serves me correct, I think this seems to happen when we move from colder weather to prolonged warmer weather - just a theory - probably clutching at straws. I will work on the boiler this week and will be looking at the same components as you. I have changed the majority of components on this boiler in the last six years due to various problems and am now of the opinion it is inherently a bad design. I will report on my findings.

Have you had any luck since posting?

oliveoil54

Sorry to hear you are having the same problems, know exactly how you feel.

Have changed 3 thermostats so far, boiler themostat (still no control), heat store thermostat, tank limit thermostat. Still with no improvement.

Next step is to change the motorised valve actuater. Can get heat to radiators by latching the actuator arm into the manual latch & leaving it there, but its only a temp position as it gets too hot at 90 deg.

Checked expansion vessel pressure & its ok.

Will be very keen to know if you have any luck, please let us know how you get on.

Datcher

Having been away for the weekend I expected to come back to a boiler overheat. This was not the case and the boiler has been fine since (touch wood etc etc).

One thing I forgot to say was when I get an overheat/high temp situation, I temp to bleed the auto air valve and all of the grey bleed valves. At high temp it is generally steam that is released. I then reset the system pressure to approx 1.5bar.

I am wondering if the 'steam' is the product of the high temp or if there is air in the system and this is causing the high temp ? Anyway, after a bleed/reset the system seems to calm down for a while and probably means I have a small leak.

Although I'm no heating engineer (aircraft engineer by trade), if I was you I would give the boiler and the rads a good bleed (disconnect the burner plug and call for heat via the room stat to provide flow), keeping the valve in the default position so as not to introduce more air into either system.

Apologies if I'm covering old ground.

Datcher

I know it's been a while but did you get to the bottom of the problem?