Everything seems to work OK at first.
Controls call for heat
Fan starts.
Usual clicks an noises.
Spark starts.
Pilot lights.
Main burners come on - Whoomph
Fires for between 2 - 10 minutes depending on how cold it is to start.
Tick noise - then main burners, pilot, everything goes out.
System still calling for heat.
Ignition still firing (spark still showing - I can hear regular ticks)
10-15 minutes laters after boiler has cooled down - system will reignite (pilot, main burners etc)
Then shuts down after 2-5 minutes again and goes through this cycle again.
So that's the problem - now some other stuff that might help diagnosis:
Radiators come on fairly quickly.
All radiators get heat at same time. No cool radiators (all rad valves open)
If boiler runs for 10 minutes they are all nice and hot (although cooler at bottom - but this could be they just don't have time to heat up properly?)
All rads bled and air free.
Loft Expansion tank seems to be working OK.
I drained some water from the system (at the boiler ) and loft tank filled up again fine.
Rad circuit is 15mm and also microbore 8mm
Boiler sounds fine when getting hot - no kettling noises.
Overheat button not popping out.
Boiler never gets as hot to the touch as is used to when running normally (just gets warm).
Happens on both HW and Heating.
With heating the return pipe to the boiler takes a while to heat up - but at a bout the time it cuts out it is starting to get hot. Eventually it will reach about the same temp. as the flow pipe (of course the flow has cooled down by now as the boiler has cut out).
With hot water on (immersion on also) flow pipe gets v. hot quickly - return pipe gets v. hot also - maybe 10% difference between the two. Still runs for a few minutes then cuts out.
Water pump appears OK.
Removed Grundfos screw - and can see pump spinning - changes speed from settings 1,2,3 and goes nice and fast on 3.
Took it apart and gave it a clean - no nasty rattling or scraping sounds.
Recently had new fan fitted.
Some things have read suggest that circulation problems can cause the boiler to overheat and cut out - and issues could be:
Air lock (have an automatic air lock removal thing that I could hear cutting in fine when I took the pump apart for a clean)
Faulty pump
Bockage in pipes (usually cold feed - but when I ran water through from the loft tank it all seemed pretty clear) - not a huge amount of gunk in there.
So - before I buy a new pump / drain the system / pay for a powerflush etc etc - what do you fine gentlemen and ladies think?
Boiler or circulation system?
Thanks for your advice.
Controls call for heat
Fan starts.
Usual clicks an noises.
Spark starts.
Pilot lights.
Main burners come on - Whoomph
Fires for between 2 - 10 minutes depending on how cold it is to start.
Tick noise - then main burners, pilot, everything goes out.
System still calling for heat.
Ignition still firing (spark still showing - I can hear regular ticks)
10-15 minutes laters after boiler has cooled down - system will reignite (pilot, main burners etc)
Then shuts down after 2-5 minutes again and goes through this cycle again.
So that's the problem - now some other stuff that might help diagnosis:
Radiators come on fairly quickly.
All radiators get heat at same time. No cool radiators (all rad valves open)
If boiler runs for 10 minutes they are all nice and hot (although cooler at bottom - but this could be they just don't have time to heat up properly?)
All rads bled and air free.
Loft Expansion tank seems to be working OK.
I drained some water from the system (at the boiler ) and loft tank filled up again fine.
Rad circuit is 15mm and also microbore 8mm
Boiler sounds fine when getting hot - no kettling noises.
Overheat button not popping out.
Boiler never gets as hot to the touch as is used to when running normally (just gets warm).
Happens on both HW and Heating.
With heating the return pipe to the boiler takes a while to heat up - but at a bout the time it cuts out it is starting to get hot. Eventually it will reach about the same temp. as the flow pipe (of course the flow has cooled down by now as the boiler has cut out).
With hot water on (immersion on also) flow pipe gets v. hot quickly - return pipe gets v. hot also - maybe 10% difference between the two. Still runs for a few minutes then cuts out.
Water pump appears OK.
Removed Grundfos screw - and can see pump spinning - changes speed from settings 1,2,3 and goes nice and fast on 3.
Took it apart and gave it a clean - no nasty rattling or scraping sounds.
Recently had new fan fitted.
Some things have read suggest that circulation problems can cause the boiler to overheat and cut out - and issues could be:
Air lock (have an automatic air lock removal thing that I could hear cutting in fine when I took the pump apart for a clean)
Faulty pump
Bockage in pipes (usually cold feed - but when I ran water through from the loft tank it all seemed pretty clear) - not a huge amount of gunk in there.
So - before I buy a new pump / drain the system / pay for a powerflush etc etc - what do you fine gentlemen and ladies think?
Boiler or circulation system?
Thanks for your advice.
