ideal classic boiler overheating

[GWILSON1]

Hi - Anyone have any idea what could be wrong with my boiler or heating system??? I have an ideal classic ff250 (bout 7yrs old) - always serviced - recently started to pop out the overheat/reset button. Its been checked by a reg gas eng/plumber who's having difficulty resolving the prob. The boiler itself works fine on hot water only - but on either heating or heating and water the boiler casing gets extremely hot - and eventually pops the oheat/reset. The heating system (vented) as been power flushed, changed the pump and the diverter valve (as they were a bit clogged up) - but still not resolved.
Confused ...... ?????

 

[namsag]

Faulty boiler stat/ overheat stat .

 

[GWILSON1]

Hi - Thx for quick response - I forgot to post - limit stat (reset) has been renewed and stat sensor harness also renewed
Regards
G

 

[bellairaphon]

could be a filter blockage or airlock

 

[gas4you]

Has the water level, or lack of it, in your header tank been checked?

 

[shambolic]

More likely a circulation problem than a boiler one TBH!
Possible airlocks or blockage Ps was the pump fitted in the right direction?
Good indication of reverse flow in a classic is the noise constantly like bubbles running through the boiler when pump on!

 

[Agile]

A better indication of the flow rate through the boiler is given by the temperature differential across the flow and return.

It should be a nominal 11 °C.

However you have said nothing about then boiler control stat setting! Have you turned it down and if so whats the result?

Tony

 

[Kev F]

always best to leave on nothing higher than 4.

 

[shambolic]

always best to leave on nothing higher than 4.

Aye right
So the thermal store its fitted to(in some cases) will never shut the boiler off as it doesnt get to temperature of 80.

Also would it not be better to have 82 deg going to the cylinder at all times as the cylinder would cut off on cylinder stat quicker?

This depends on the correct fitting and flow rates through boiler and pump though!