Boiler Packed Up

[Tim+]

Number 6 in the drawing in the manual.

Tim

[Brian Gaff (Sofa]

At least it had the sense to fail in the summer not on the coldest day of the year I suppose. Brian

[Andy Bennet]

Oil? Feed blockage?

[Michael Chare]

The power supply cable to the burner can be unplugged. Not all oil boilers let you do this. It is shown in the manual and can be done on an earlier version of the boiler which I happen to have.

[Dave Liquorice]

Or the boiler is controlled via a microswitch on a valve and the microswitch has failed or the valve is responding but is gunked up and not opening enough to operate the switch.

[Martin Brown]

Cleaning the photosensor is always the very first thing to try - especially after high winds from unusual directions.

+1

Does the ignition spark actually occur but no flame?

Does the blower run?

Does it smell of kerosene after failing to light?

Weirdest one mine ever had was that it would lockout and not light the very first time every morning. Turned out to be a failing fuel solenoid allowing a tiny leak that made a bad sooty flame in the first ignition that caused immediate lockout. Reset and retry and it was fine all day.

Until the next morning when it failed exactly the same way...

[John Rumm]

If its a conventional wiring with the microswitch firing both the pump and boiler, then it must be ok if the pump is running. Likewise if the boiler controls the pump, and its running, then the call for heat must be getting as far as the boiler.

[Mike McLeod]

Well, yes, it *had* tripped. I couldn't find it! I had to call out the engineer in the end. I don't *fully* understand what happened, but the gist of it was the expansion tank had failed, the pressure in the system had fallen too far, some overheating had occurred somewhere and the overheat stat tripped out. If it had just been the trip I'd have been really pissed off with myself, but the fact that the tank had to be replaced anyway made it worthwhile calling out the engineer, so no regrets over the expense. :-)

[Andrew]

Does central heating oil suffer from the same issue as red 'bio' diesel ?. The latter apparently grows bugs that clog up the tractor/combine harvester fuel filters annoyingly often according to someone with farming connections who posts here.

[The Natural Philosopher]

does the air pump spin up and the igniter crackle?

[The Natural Philosopher]

classic lockout for me is when a gale blows from one direction. the balanced flue is short and it blows the flame out

[The Natural Philosopher]

if it tries and fails might be a flame sensor

[The Natural Philosopher]

there is an air pump as well. That you can hear

[Cynic]

Glad to hear you're fixed. However it's worth mentioning to all the blocked fuel supply proponents, an oil boiler sequence control expects to start the ignition cycle with a dark combustion chamber then see a flame within a short time. If neither of these conditions are satisfied the burner locks out and an indicator lamp(s) light up. It might also be worth adding that most of the oil combis I've ever worked on have the diverter valve and pump(s) in the package so "plan" systems are generally unnecessary. However I do recall fitting one to a large farmhouse so upstairs and downstairs could be programmed for separate times. The cost of a manufacturers expansion vessel can be quite daunting hence if possible I usually fitted a robokit somewhere convenient and tapped it into the pressurised system. Saved a lot of dismantling and allowed use of a larger expansion capacity.

[Mike McLeod]

Thanks for your interest, but it's been fixed now (expansion tank membrane perforated).

[Michael Chare]

I wonder why that happens. I have an earlier non condensing version of that boiler, and the expansion tank was changed for the previous owner of the house.

[Cursitor Doom]

Well that membrane is continually "in flux" as it were and like anything else that moves, that causes wear.