Hi.
The boiler for my central heating is behind a radiant heater in my front room. Recently, it stopped heating the water properly, and I discovered that the boiler had sooted up. I cleaned it, but the problem re-occurred just three days later.
I think that the flame looks too yellow. Any idea what might cause that?
Picture 62kbytes, showing burner and sooty boiler.
Too much fuel/not enough air. This is potential lethal, so turn it off until you get it fixed. Have you got a carbon monoxide detector? If ventilation to the room and front of the boiler is okay you should check the flue isn't blocked.
In message , Dave Farrance writes
yellow flame is producing soot AND carbon monoxide, so if you can't find an obvious reason, get someone in as it's dangerous
That takes me back a few years to when I last owned a Baxi Bermuda!
How did you clean it? You need to turn the gas off, disconnect the crane joint, and slide the controls and burner out from under the boiler.
Then clean *between* the two halves of the boiler with a bottle brush. The boiler is like two chunky bars of chocolate, facing each other. You need to get all the soot off the chunky bits.
Then you need to clean the burner itself - best done with a dusting brush on a vacuum cleaner to make sure you suck up all the crud. Most importantly, make sure that the air ways to the main jet are clear - yellow flames are usually a sign of insufficient air. Talking of which, the room where it is installed *must* be well ventillated - with a decent sized air brick at least.
From the photo, the *front* of the boiler looks sooty - as though the flames have been lapping round the front rather than going up the middle. Is it? It makes me wonder whether the chimney is drawing properly. Not blocked with birds' nests is it? You need to get a smoke match and do a smoke test to ensure that the smoke goes up the chimney and not into the room!
Meanwhile, I hope you're saving up for a new boiler! Bermudas were good work-horses in their time, but they're very inefficient compared with modern boilers - and not that easy to maintain when they start giving trouble.
Thanks. I cut off the gas when I realized that it must have developed a fault. I've looked at the construction of the gas burners for the radiant heaters and I can see that air is mixed in with a jet. Presumably there'd be something like that for the burner under the boiler, although I can't see it because there's things in the way. If a yellow flame is caused by lack of air, then maybe there's an air intake that's got blocked. Is that a reasonable assumption?
I checked the flue, and it's perfectly clear. When it's burning, even with the yellow flame, smoke from a match gets sucked towards the boiler, then up the flue, so I guess that any CO would have gone in the same direction. Anyway, it's off now.
Yes, I realize that. I might well end up getting someone in, but I like to know what's gone wrong first, so that I'm not told that the whole central heating system needs replacing. :)
Ah, I didn't realize that the burner assembly could be slid out. And that crane joint looks like it'll need three spanners to avoid putting strain on the pipes, and the nut seems to need a one and eleven-sixteenths spanner, which I don't have. Maybe I'll buy a large adjustable spanner.
I fixed newspaper over the burners with masking tape, then cleaned the boiler with the burner in place. And I discovered how difficult it is to buy a bottle cleaner these days. I eventually found one in an Asian general store.
Evidently that's the next thing I've got to do.
Yes, I guess I could check the room vents with that bottle cleaner.
The gap between the two halves of the boiler was solid with soot. Luckily it was soft and easily brushed out. Also luckily, the flame licking round the front warmed the thermostat at the front, and kept cutting off the burner after a few minutes, so it was obvious something was wrong. And yes, I've done the match test, and it's OK.
I used to clean out my parents' Ideal Standard boiler, not a back boiler, but otherwise similar.
I'm not familiar with your particular boiler, but the sooting up mechanism is pretty common to them all. Once it starts, it runs away rapidly. Soot produced on the heat exchanger reduces the airflow, causing production of more soot. Soot also falls off the heat exchanger into the burner, and depending where the air intake is on the burner assembly, this blocks it and produces even more soot. A boiler can go from apparently working to sooted up very quickly.
What starts it can be down to chance, such as when a gradual buildup of dust crosses a threshold. It might also be a more definate event such as something suddenly blocking the flue.
That's probably not good enough. You need to go to a plumbers merchant and buy the proper brush, which will be a stiff wire one of the right dimensions to fit exactly into the heat exchanger. What you've got probably won't be cleaning anything like well enough.
Yes -- the instant re-sooting up indicates the problem is not fixed. The other thing is to be sure you did actually clean the whole heat exchanger, and haven't missed anywhere. I used to use a light at the bottom and mirror at the top to make sure there were no areas missed, as again that will cause instant re-sooting.
intake
Yes it is. You know you said you did the smoke test? did you try it at the base of the boiler where you can see the main burner, or under the draught hood? I'm concerned that even though you have cleaned the boiler fins, there is still blockage between there and the flue?
Rich
Thanks. I'll bear that in mind.
The bottle cleaner *seems* OK, and by luck it is of the right dimensions. And I need to bend the wire handle at right angles to get in at the sides, because access is restricted.
Yes, I figured out the use of a light and mirror. :)
No, you only need two! The big nut holds two conical shaped bits together. You need a 25mm or 1" spanner to hold the bit it screws *onto*. You can then undo the big nut itself with a decent pair of water-pump pliers - and finally, ease the two bits apart with a screwdriver. [I've still got a crane joint which I rescued when I junked my Bermuda about
10 years ago, and have just had a look at it in the garage.]
The most likely cause of your problem is crud blocking up the main air intake. I can't remember where this is, but if you follow the pipework from the crane joint to the gas valve and on to the jet, it should be obvious. But you'll have to undo the joint and slide it all out first. [I seem to remember that there's a screw at hearth level under the middle of the fire which you have to undo, too - and (I think) you need to lift the front of the controls slightly to clear the frame.]
I see. Thanks.
The function of the various bits and pieces that I can see seem clear enough. I can't see the intake because it's behind the electrically operated valve (I presume), so I'll have to slide it all out first.
Before you or anyone else gets hurt stop using this boiler now.
The boiler will need a thorough going over to get back into an acceptable state. Every aspect of the combustion and flue system will need checking and cleaning.
When was the last time you had this serviced. This type of boiler will not remain safe enough to use without annual services.
What you do next will depend on your budget, and level of competence. HTH
Which frankly it does. There is a small risk that whilst trying to bring it up to scratch you find something damaged...
i think you'll find that there may be a fine gauze inside the mixing tubes (the part of the burner between the injector and the flame outlets). This is easily blocked by very fine dust and washing it out is often the best approach. Dry well afterwards.
Thanks. I've removed the burner's jet, and found some soot in there, which probably fell from the boiler. I can't see very far inside the burner, and can't see any gauze, but I'll wash it anyway.
As regards your other comments in this thread, yes, I realize that it needs a professional examination, and probably replacing, and I will arrange that. Since that's likely to cost a fair bit, I'd rather not have to make a quick decision because I've currently got a non-working boiler.
I had to lift the draught hood out to clean the boiler fins, and it's OK. The flue is wide and clear, and gives good suction.
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