Combi cutting out

[bunser]

Our combi boiler is cutting out after the overheating light flashes.(obviously overheating)
If i turn down the comfort switch to below 4 the temperature light stays at 80 deg and the overheating light does not flash. Does the comfort switch adjust the flow of water or the amount of gas?
Could this be due to a slow pump and is there a way to check pump speed with a multi meter. If I unscrew the end cap on the head of the pump, water sprays continuously, is this normal? The heating side works fine.
The combi boiler is a Radiant Bruciatori RSF 20-24 pilot flame.
Thank you

 

[Paul Barker]

pump sludge or both. Remove pump not just head, inspect whole thing, take it off use a pair of buckets does it pump from one to other in about 10 seconds? It's OK.

Heat exchangers need a clean thermisters if wet pocket also need cleaning.

 

[bunser]

The Pump has been stripped and cleaned, heat exchangers cleaned also no sludge or build up etc. Forgot to mention that after the light flashes the boiler shuts down and has to be relighted. have not tested the pump off of the boiler. Whats thermisters?
Thanks

 

[John_D]

The heating side works fine.

so this is about the tap water, expect the heat exchanger may be scaled up, get it descaled by a powerflusher or replaced.
the water goes through the heat exchanger and gets too hot so the boiler cuts out

the screw cap on the pump is for bleeding it, it would spray water till the system pressure drops

 

[bunser]

The heat exchangers have been descaled. I was talking about the cap in the centre on the end of the pump spindle (motor side) not the bleed valve.
Thank you

 

[Paul Barker]

That cap is where the pump is blead.

Not familiar with ure boiler whatever form of temperature senser it uses needs proving and dhw heat exchanger needs investigating furthermore or again.

 

[bunser]

Is there anyway to test the pump speed without removal
Thanks

 

[Paul Barker]

Not familiar with the boiler but if u are scared to remove the pump u don't sound like the sort of person who can fix it.

 

[Agile]

If this is the model with the "L" shaped combustion chamber cover they are very prone to getting debris trapped at the 90° elbow on the flow connection to the primary HE.

Removing the connection will usually expose a build up of oxide debris.

Tony

 

[namsag]

Nickso do BG still have limpet facility on lap top. As for checking pump speed and functioning correctly while still in place

 

[nickso]

Nickso do BG still have limpet facility on lap top. As for checking pump speed and functioning correctly while still in place

they do still have it although there was a shortage of test leads for some time.

i never really trusted it though as it quite often gave poor results. it was always a last resort for me.

edit: sorry i just reread you post and in actual fact the best thing about it was for testing the pump speed and electrical integrity of the motor. it only really failed once sludge and other such factors were involved.

 

[bunser]

"Not familiar with the boiler but if u are scared to remove the pump u don't sound like the sort of person who can fix it."




Paul Barker,
Funny thing but i was thinking exactly the same about you lol.

 

[Paul Barker]