Pottertonpromax he plus overheating

[jren]

Hi Everyone
I've searched for any clues to this one but coming up short.
Boiler was working fine was running low (half temp) on ch dial...
External controls running ok.

Then boiler starts to over heat.
Ch kicks in water heats but not going anywhere, pump red hot boiler locks out
Display shows water temp rising to 90 even when dial is only at 6 o'clock

Pump head replaced, now can hear pump running but same problem, feed into the pump
Is too hot to touch, pump is too hot to touch, pipe work after pump is hot for approx 6 inch. ( probably heat transference

Hot water works fine

No previous blockage as far as aware, magna clean on system, boiler fitted Feb 2014
Only two things that come to mind are
Change whole pump with auto vent rather than just pump head or blocked heat exchanger??
Other fact not stopping when reaches dial set temp rises to 90 then kicks out. Last time I moved the ch dial on panel it went to max 30 not 80 which seemed a bit strange.

Would really appreciate any input!

 

[jren]

Wow so many replies and advice!!!
To update
I've stripped the entire pump and checked it...
No blockages pump spinning fine... But not circulating the heated water ????
I've stripped the diverter valve and that looks dodgy so I'm going to replace that.
Heat exchanger shows no sign off deterioration,
Can't explain why the system is allowing the ch to heat up past the dial set temp
Hot water working fine ??

 

[ianmcd]

your boiler doesnt have a diverter valve , do you mean the 3 port motorised valve ? Y plan , or do you have two 2 port valves ,S plan, if you are not sure , post a pic of what part you are referring to

 

[stem]

First of all, When you say that it is overheating? I assume you mean that the safety overheat is tripping, is this correct? If not, it's probably OK. If the demand for heat is low, the residual heat once the burner has closed down may be causing the temperature to continue to increase beyond the set point.

When the temperature gets higher that it should, but before the overheat trips; is the burner still lit, or has it gone off?

If it is tripping the overheat, that suggests to me that there is insufficient flow of water through the boiler to disperse the residual heat once the burner has closed down and so the temperature continues to increase.

I assume that it has worked OK previously. So, has anything changed that may have restricted the flow though the heating circuit, such as additional TRV's being fitted? Have you switched off any radiators that don't have TRV's and that should be left open to maintain the flow through the boiler? (usually in the room where a room thermostat is located) or adjusted any by-pass valve?

It may be that there is a problem with the boiler's control circuits that is allowing it to overheat, but if it doesn't trip when only the hot water is on, and that it works OK on the half heat setting that would suggest, perhaps not. Even if this were the case, for your safety, the Gas guys are unlikely to give you advice, other than perhaps to call a professional.

 

[Ihavenojob]

Are we talking combi ? If so there is possibly a mesh filter in the return isolating valve which could need cleaning.

 

[stem]

Are we talking combi ?

No

Pottertonpromax he plus overheating

It's not a combi

 

[Ihavenojob]

Promax he plus is a combi, the heat only ones don't have any display on them.

 

[stem]

There is a Promax Combi, but the Promax HE Plus is heat only.

 

[Ihavenojob]

The op is a bit lacking when describing the boiler, I guessed he was on about a combi when he said pump with auto air vent, display on the boiler & cleaning the diverter valve, though I may be wrong.

 

[Agile]

Hot water working fine ??

That seems to imply he has a combi.

But his vague style of writing makes it very difficult to help him.

I also suspect he is opening his room sealed boiler for DIY repairs!