Lasting 50 years I presume makes it a cast iron exchanger. Presumably the ' rods' are short things moulded into the iron to improve heat exchange. So i t'll be in the 60s of % efficient, with a lot of thermal inertia. So you're paying around 50% above a modern boiler's gas bill. OTOH no endless repair & replace costs. There's always the risk you might need repair and/or repl acement though.
NT
45 years ago the average efficiency for an Ideal Standard gas boiler was in the region I specified. Manufacturers figures. A modern boiler is not much better if in non condensing mode.
he 'rods' are short things moulded into the iron to improve heat exchange. So it'll be in the 60s of % efficient, with a lot of thermal inertia. So yo u're paying around 50% above a modern boiler's gas bill. OTOH no endless re pair& replace costs. There's always the risk you might need repair and/or replacement though.
that would explain it, it was a manufacturer's figure. It's also a differen t boiler.
NT
I would expect something like 60 to 65% for a non fan, open flue, permanent pilot boiler. Perhaps mid 70s for a more recent balanced flue version. However those figures could be lower if driving a poorly matched load, and by having poor system controls (i.e. no pump overrun).
The matching problem is less of an issue with modulating boilers.
of the boiler casing.
cleared this when we had the problem. I'll contact him and verify again and report back next week. I do hope this is the problem!
Blue flames outside the case !! Wow, it should be all airtight.
It's probably similar to my faithful old Glow Worm Space Saver 50 installed new in the 1970's I believe. This has a cylindrical steel burner around
2" diam that just drops into place around the jet. You take the white ename lled cover off first (wing nuts at the back), then take off the internal co ver around the burner which, from memory, just clips into place. I found some spares easy to get on the internet around 12 years ago.
This means the channels up through the heat exchanger are blocked. Almost certainly nothing wrong with the gas valve or burners.
First thing, you need to get a different Gas Safe engineer (or CORGI in Northern Ireland). The one you have is incompetent - he has wrongly diagnosed the problem, and should have disconnected the boiler as unsafe.
You said there was a fall of soot - where from? You probably need to get the chimney swept before cleaning boiler. Then you need to get the boiler serviced by someone who knows what they're doing. This involves removing the burners and getting access to the combustion channels and using a stiff brush to brush out all the soot, being careful not to knock off too many of the heat exchanger nipples. (Brushes are sized and shaped to fit channels in different boilers.) Use mirrors and lights to ensure the channels are completely clear of soot. Then the burners need soot and dust cleaning out, and ensuring jet(s) and mixer tubes are clear (might be one for all of them, or one per burner, depending on design).
If the boiler is running properly, no soot is formed. In normal operation, a small amount of solid debris forms (burned dust, flies, etc) inside the heat exchanger. This falls off and can get into the burner air intake (together with dust). As the air intake gets restricted by dirt, the flames will start to generate soot, and this drops back and rapidly makes the situation worse. Within a couple of weeks, the effect will "run-away" rapidly generating more soot, which rapidly makes it worse until it's ended up in the state yours is in.
It's an open-flued boiler and extremely dangerous to use in this state, as it will be generating carbon monoxide in addition to soot. This type of boiler really does need an annual check, and you should have carbon monoxide detectors fitted and tested at the same time.
They aren't worked out in the same way. You can't compare the figures. (In particular, the original manufacturers figures won't allow for the heat wasted by a continuous pilot light, but also the calculation methodoligy has changed at least twice since then.)
Gas boiler of that age I used to service had a completely different design of gas valve. It used (abused?) a pressure reducing valve to operate as a gas valve for the main burners. It exposed what would normally be the air pressure side to gas pressure via a tiny orifice, which shut the thing off. To turn it on, it had a tiny gas valve which let the gas pressure leak away from the normal air side, which opened the pressure reducing valve (and it burned the leaked-away gas in an extra single burner).
If it's that bad, I would say it's had it. However, I never saw a burner that needed anything other than cleaning.
Like I said elsewhere, no evidence was posted that there was anything wrong with the valve or burner (beyond normal servicing). I strongly suspect the problem is blocked flue channels through the heat exchanger, having serviced similar boilers myself in the dim and distant past.
Just to close this off, Andrew was quite correct. The combustion channels were totally blocked with soot. Once we cleaned this out the boiler worked perfectly. I shall make sure this is done every year from now on. Many thanks for this valuable advice which hopefully resulted in many more years' service from this boiler. John
Chances are it went without a clean for *a lot* more than a year if it sooted up. But once it starts, it blocks very quickly.
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