Oil boiler cycling in and out every 10 seconds!

Bif

Folks,
What might be causing the above? The boiler is cutting in and out every 10 seconds but heating the rads without cutting out. This seems very short...what might be causing it? The circulating pump was replaced recently and ran fine till now. Thanks.

jimf

a few things really could be causing this issue

a dirty or faulty photocell

b fuel pump slipping or fuel starvation

c a leak of combustion gasses could be getting sucked into the air intake

d partially blocked nozzle


as you can see its total guess work without been on site

John.G

or just maybe low system pressure if a unvented system or no water in feed&expansion tank if vented.

jimf

John.G wrote: »

or just maybe low system pressure if a unvented system or no water in feed&expansion tank if vented.

would have though the cycle time would be an awful lot longer if this was the issue john

10 seconds sounds way too short

John.G

You are spot on there I'd say.
Think I had this myself about 5 years ago (Firebird SE boiler) it happened after I got a refill of oil and even though it only lasted for a few minutes never to return I just wondered if somehow there was entrained air in the oil which would have been agitated by the new fill, incidentally this boiler has never tripped on flame failure in 14 years of service.

jimf

John.G wrote: »

You are spot on there I'd say.
Think I had this myself about 5 years ago (Firebird SE boiler) it happened after I got a refill of oil and even though it only lasted for a few minutes never to return I just wondered if somehow there was entrained air in the oil which would have been agitated by the new fill, incidentally this boiler has never tripped on flame failure in 14 years of service.

as a rule it should have no air in the line unless you run out of oil john but as you say agitation of the tank contents maybe a cause

the fb se boilers are/wer a great boiler with minimal care and servicing they seem to go on forever

my own is a popular 90 fitted in 1995 still going strong

note to myself it needs a service but her indoors wont pay me to do it so no money in that job

Bif

Thanks lads. I pulled the photocell and it was dirty. Cleaned it and that seemed to do the trick. Unfortunately the core issue may a boiler leak as it is damp underneath the boiler and maybe that caused the photocell to get dirty if the boiler is leaking into the burner / flame area. How much is new boiler to have installed? It is a Grant Euroflame, fitted 20 years ago.

jimf

if you pull the burner from the boiler see if any water in the combustion chamber

dirty cell probably caused by poor combustion due to lack of servicing and setting up properly

water underneath doesn't sound good but first port of call is to identify where leak is coming from

very approx. price to supply and fit new boiler 2.5k

Wearb

Bif wrote: »

Thanks lads. I pulled the photocell and it was dirty. Cleaned it and that seemed to do the trick. Unfortunately the core issue may a boiler leak as it is damp underneath the boiler and maybe that caused the photocell to get dirty if the boiler is leaking into the burner / flame area. How much is new boiler to have installed? It is a Grant Euroflame, fitted 20 years ago.

If there is a Safety pressure release valve fitted on top of the boiler, that's the first place to check to see if its letting water through. Otherwise do as Jim says.

Depending on how that valve is installed, water from it could show up anywhere around the boiler.

John.G

If vented tie up the ballcock and see if level drops in tank. If unvented ensure the "Autofill" valve is shut and watch for fall in system pressure.

Bif

Thanks all. Vented system and the safety valve was replaced a couple of months ago with the circulation pump and pump isolation valves....looks to be dry enough.. I will investigate further as water leaks can be hard to pin down. Indoor boiler so some clearing to be done first!!! Thanks for the advice...keep it coming!

jimf

any washing machine etc in the general area ????

Bif

jimf wrote: »

any washing machine etc in the general area ????

Washing machine, dryer and sink!

jimf

Bif wrote: »

Washing machine, dryer and sink!

some investigating to do so be careful you don't end up needing a new utility



had a boiler a few years ago suspected leak it was the pipe from the washing machine that was the culpit

littlecopilot

My firebird burner was doing this exact thing for last few weeks. Cutting out every few seconds. I just changed the jet and it solved the problem for me, but I guess it can be a number of things and I was just lucky

jimf

littlecopilot wrote: »

My firebird burner was doing this exact thing for last few weeks. Cutting out every few seconds. I just changed the jet and it solved the problem for me, but I guess it can be a number of things and I was just lucky

yes the nozzle can cause the very same symptom as it can get partially blocked thus the burner oil/air ratio is changed and the burner is now very over aired blowing the flame off the end of the blast tube