Our boiler has just started switching itself off after a few minutes running, it will try and restart and will run for a short while but then stop again.

Just before it stops it sounds (and looks) like it’s running out of oil but there’s plenty in the tank.  I’ve checked the filter in the [Riello 40] pump but it’s pretty clean and the valve solenoid tests OK.

Jet hasn’t been changed for a while so I’ll try and get one tomorrow but I’m not sure it’s that as it starts and runs fine for a while.  Certainly sounds like fuel starvation.

Is it possible for a solenoid to repeatedly open properly initially, then fail after a short while?

Frozen condensate in the short exposed run of pipe that feeds oil to the boiler from outside? Find the pipe and pour boiling water over it?

firevalve shut its self for some reason./failed.

had similar symptoms on my grant but was my firevalve was triggering at much lower temp than it should.

Have a look at the tank filter bowl may have ice in

The  solenoid runs on two powers a higher voltage to get going the drops in he power down after 30 second or so

have a quick look at the photo cell start the boiler when it tries to fit pull the sensor out and shine tourch on it see what happens

what boiler is it ?

If it runs for about 10 min to start with then again for less and less each time it’s probably the solenoid starting to break down.

If it starts and runs ok for more than 40 sec it’s probably not the photo cell as if it’s not registering darkness it won’t fire and if it doesn’t register light it won’t run for more than 10 sec or so (but worth giving it a clean anyway!)

RT has the probable cause. Get a coil as well as a nozzle.

Sounds like the circulation pump has failed

Sounds the same fault we had on tuesday night, oil pipe from tank to filter blocked with gunge and ice,  removed pipe and flushed through. Couldnt believe it, iust shows ho low temp plus wind chil . Pipe now lagged.

Sorry, should have elaborated ….

It’s an old mistral boiler,, not condensing – basically an empty box with a Riello 40 burner on the front.

No filter bowl near the tank that I can see and oil line runs mostly underground – oil is running fine, but I’ll try hot water on the exposed pipe.

If the fire valve had triggered I would have thought the boiler wouldn’t run at all – I can keep pressing the reset button and it will always restart and run for a short time.

Cleaned the photocell and reckon it’s ok for the same reason as above (no photocell, no fire).

Didn’t know solenoids can break down – they do seem to be an issue. I’ll try and get one in the morning.

Pump to motor coupling would be my guess.

Its just a bit of plastic and simple to replace if you can find one.

But if the pump wasn’t working then surely it wouldn’t fire at all?

Plus on initial fire up it runs for 10 mins or so which it could never do without a fully operating pump.

Worth bearing in mind though.

Update time:

Went out this morning and got a new solenoid and jet – they didn’t have a needle valve in stock.

Cleaned everything up, fitted the new parts and the boiler fired up straight away (as it did before).  It’s now been running for about an hour but it’s recently restarted a few of times and I can see/hear the burner misfiring a bit before it shuts down.

So – not fixed yet.  I’ll try and get a needle valve and if that doesn’t do it then it’s probably new pump time as there’s basically nothing else to replace!

Obviously it ‘might’ be a feed issue but I’m not so sure about that.  Maybe it is though….. I’ll chuck some hot water on the external oil feed pipe.

Oil supply could be a problem from your recent description.

Sounds like it could be a blocked filter. Oil will be flowing but not at a fast enough rate to keep up with the burner, what tends to happen is if it has been off for a while the oil will fill the pipe and / or filter bowl, it then fires uses up this small store of oil then starts misfiring again. Leave it off for a while again and reset it and all seems good?

Look at the tank end to see if there is a filter built into the control valve.

Well having said that there was no inline filter….. I’ve just found one!!

[I’ve only lived here for 16 years… give me a break 😉 )

Took it apart and the the filter was covered all over with a healthy layer of black slime.  Removed, cleaned up in petrol and re-assembled.  Boiler fired up and running as I type.

Bear – sounds completely feasible and probably right.  It really sounded/looked like it was running out of fuel but as I thought I’d checked all the filters I had decided it couldn’t be that!

If this now works all it’s cost me is a new £20 solenoid as the jet needed replacing anyway.  Plus I’ve learnt a lot about the burner and how to service it 🙂

I will update again later.

Well it’s been running perfectly for an hour or more…. job jobbed I think.

Thanks for the pointers.

Nice one. I’m on Oil and the boiler is over 20 years old. It needs a bit of TLC to keep it going but I can’t justify a new one yet. Things go wrong but they are usually an easy / cheap fix.

Had a similar problem a few weeks ago, turned out to be water in the oil tank building up from condensation on the inside. As it builds up at the base of the tank what was coming down the fuel line was sort of a watery emulsion. Once tank was pumped out (just the water from the base plus a little excess oil) it was fine. You can get water detecting paste stuff for a few quid you smear on a stick and dip in to see if there’s any there and how deep it is (it changes colour).