Pumped system boiler trips flue thermostat

[stevo185]

I have an Ideal Minimiser boiler. When hot water is switched on, it works fine, burning for a while then controlling on the boiler stat. When I put the heating on, the boiler burns, the radiators get hot, but the boiler stat never cuts in and eventually the flue stat pops. I can switch off, open the panel and reset, then it will do exactly the same thing. Both the boiler and flue stats were replaced just over a year ago.
So the boiler stat seems to be working, just not when heating is on.
Any suggestions as to where the fault might lie please.
Steve.

 

[ianmcd]

when was the last time that you had the internals of the heat exchanger cleaned properly ? these boilers are terriible designs and proper cleaning of the heat exchanger fins is crucial and very difficult to do

 

[stevo185]

Boiler was cleaned and serviced last year. Not sure how that would produce symptoms I have. I'm not familiar with the electrics up in the loft that control pump and motorised valve, suspect something is amiss there.

 

[ianmcd]

I have a lot of experience with this boiler Steve, and if you havent had a complete , heat exchanger clean then that will be your problem mate, you have a very poor boiler and I would budget to replace as soon as you could afford it

 

[45yearsagasman]

+1 for me. Those heat exchangers are notoriously difficult to clean effectively. Even experienced guys find it so. That is the most effective brush that can be used on these boilers. A good service on these will take in excess of an hour. I bet your man didn't do that.View media item 44168

 

[Agile]

For the few that are still working I would recommend that it is serviced every six months as they get gunged up so often.

Tony

 

[ianmcd]

+1 for me. Those heat exchangers are notoriously difficult to clean effectively. Even experienced guys find it so. That is the most effective brush that can be used on these boilers. A good service on these will take in excess of an hour. I bet your man didn't do that.View media item 44168

That is exactly what i use pete although I have a deluxe wooden handled one that I cut down, ironic really that you have to use a loo brush because the boiler is an absolute pile of shoite

 

[stevo185]

Sorted. Obviously one of the connections to the side of the boiler is intermittent. Wiggled them all and now working perfectly. Still don't know which one it is/was. Will keep searching for a schematic to understand the control system.
Steve.