Oil-fired boiler problem

[Boxersoft]

Danesmoor Worcester (15/19). Recently noticed a bit of an oil smell from the boiler but no obvious leak and apparently working OK. This morning it locked out. Reset OK, but locked out again after a couple of hours, and subsequent resets only lasted perhaps half an hour.

Any pointers for obvious things to check before calling in an engineer?

 

[spraggo]

Danesmoor Worcester (15/19). Recently noticed a bit of an oil smell from the boiler but no obvious leak and apparently working OK. This morning it locked out. Reset OK, but locked out again after a couple of hours, and subsequent resets only lasted perhaps half an hour.

Any pointers for obvious things to check before calling in an engineer?

Have you had it serviced recently?.

 

[Boxersoft]

Ummm... No, I'm afraid I have to confess it hasn't been serviced in the 3 years we've been here <blush>.

I've not worked on an oil-fired system before, but I became quite familiar with the gas-fired condensing boiler at our previous home. I've dug out the manual for this one and it details the steps for cleaning the burner, so I thought perhaps I'd give that a go myself. Anything particular to look out for in a unit that hasn't been serviced for a few years?

 

[spraggo]

Ummm... No, I'm afraid I have to confess it hasn't been serviced in the 3 years we've been here <blush>.

I've not worked on an oil-fired system before, but I became quite familiar with the gas-fired condensing boiler at our previous home. I've dug out the manual for this one and it details the steps for cleaning the burner, so I thought perhaps I'd give that a go myself. Anything particular to look out for in a unit that hasn't been serviced for a few years?

Soot, worn electrodes, nozzle, dirty ffd, etc, etc,

 

[slapper]

Thats why we use Flue Gas Analysers to set them up on correct burning etc. DIYers Perhaps youll want to Pilot the Plane on your next holiday.

 

[Boxersoft]

Thanks spraggo - I've given it a good clean and I'm trying to source a new nozzle before I put it back together and give it a try.

 

[Burnerman]

If the internal flue ways are clean within your boiler, the oil pump pressure needs to be 115 psi and exhaust gas set at 10.5% CO2. Unfortunately this can't be guessed, but if you can see smoke at the flue it is miles out.
Was the smell of kerosene, or exhaust fume?
John

 

[outinthestix]

If none of the previously mentioned fixes the problem, check the electrodes for cracks and leads for shorts. If ok change the EBI unit. Stix.

 

[Boxersoft]

@Burnerman: The smell was of kerosene, not exhaust. I hadn't noticed smoke at the flue, just water vapour (or that's what I've always assumed it was). I don't have have the equipment to check the pressure and CO2, so I stayed well away from any adjustments - I just wanted to get it running well enough to tide me over until I can get someone in to give it a proper service. I gave everything a good clean and replaced the nozzle, and it fired up and ran fine (perhaps more quietly than before) but it locked out again after about an hour, so I guess there's something else amiss A few years ago I was renting a place with an oil-fired boiler. That started locking out, and engineers kept coming out, tweaking things and going away saying it seemed sorted, only for it to lock out again some while after they had gone. Gawd knows how many visits we had before it was finally sorted - I hope we're not in for something similar with this one

@outinthestix: I checked the electrodes and they seemed fine to me - no sign of cracks. The burner was firing up anyway, so I figure the electrodes must have been working. I noticed that the burner was completely loose - the combustion head was simply resting in the housing, with the retaining screws backed out completely, so presumably it wasn. I don't know whether it's more likely for vibration to have worked it that loose over time, or for the last service to have been rushed and securing it was missed.


Thanks folks.

 

[Burnerman]

Thanks for the reply!
For the kerosene smell, check the condition of the flexible pipe that feeds oil into the burner. These are meant to be replaced from time to time. Also I think there's an oil tap inside the boiler casing in these - see if its damp by applying some kitchen paper, but I don't advise turning it as leaks are fairly common! Its also possible to get the odd drip from pipe joints around the pump.
Water vapour at the flue is common at this time of year.
So - where do we go from here? You can withdraw the photocell and see that its clean, and the other common thing is the solenoid coil that sits on top of the oil pump. After that, its set up time with a pressure gauge and a flue gas analyser. Even this should only really be done if the inside of the boiler is clean. After 3 years there's sure to be soot and sulphur deposits in there!
John

 

[Boxersoft]

I checked the braided hose while I had everything open, and it seemed OK to me. Unfortunately I didn't read the recommendation to replace it periodically until after I got back from town with the replacement nozzle...

Yes, there is an oil tap inside the casing. The instructions said to turn it off before opening the burner, so I did. I didn't notice any leaks from it, but obviously there was a fair bit of oil around once I started taking things apart (and, especially, after bleeding the pump after re-assembling) so I guess it will be a while before that stops masking any underlying leak.

I took the photocell out and gave it a gentle wipe, but it looked clean anyway. I hadn't identified the component sitting on the pump - is it DIY testable, or one of those 'swap it out to e safe' cases?

I've had a local engineer recommended and I've left a message on his voicemail so hopefully we'll get it looked at soon, but it's a chilly time here in Scotland at the moment and when it fired up so nicely after my efforts I really hoped I had bought us a cozy weekend in the meantime. C'est la vie.

 

[AlanE]

Running for some time then locking out can be caused by virtually blocked filter in the fuel line. If this is the case can also cause combustion chamber to soot up.

 

[Boxersoft]

Well, we did have an oil delivery fairly recently, but that was over a week ago. The tank was getting quite low, so I guess crud in the bottom could have got stirred up I cleaned the filter in the pump, but it didn't seem grotty anyway. I looke carefully at the oil that I bled off but it looked clear and free of water or crud, and seemed to be flowing well. There's a bowl of some kind under the main fuel cock at the tank, and I guess that might be an inline filter. I haven't checked it yet, but I'll try to do so tomorrow.

Thanks for the suggestion.

 

[spraggo]

Well, we did have an oil delivery fairly recently, but that was over a week ago. Thanks for the suggestion.

It is possible that you have a problem with lack of combustion air, try running the boiler with the front casing removed. If then OK there is a leak between the inner and outer balanced flue ducts.

spraggo

 

[Boxersoft]

I already tried that. I noticed an oil leak from the underside of the pump when I last checked. It seemed to be coming from what I think is a blanking plug (don't have the diagrams in front of me at the moment). I tightened that a tad which seemed to stop the leak, and I ran it for a while with high hopes (and the cover off). Locked out after about an hour again though.