Simplest way to replace the boiler...

They are basically cottect. Any new boiler has to be installed to comply with the current regulations. This may well involve changing much more than just the boiler. There are grants available for the elderly and the chronically sick.

Peter Crosland

There may not be a solution which simultaneously complies with current regulations *and* meets your friend's budget constraints!

So let's start with the basics. *Why* does the boiler need to be replaced. The only compelling reason in my view would be if it was broken and couldn't be mended through lack of spare parts. Even then, I would question how hard anyone had looked for spares.

If it really does *need* replacing, the new boiler must comply with the latest energy efficiency requirements, and the controls for the whole system must be brought up to standard - including fitting TRVs on all but one radiator. The boiler will almost certainly need to be condensing - but does

Decide exactly what needs to be done, and then get quotes from several independent heating engineers. Try to get recommendations from people you know who have had work done. Don't go anywhere near British Gas!

I quite agree, repairing the boiler would be the only low cost compliant option. Why not tell us more about the boiler.

The next lowest cost option is to fit a new replacement boiler, but its against regs so no plumber will do it, and youre not allowed to either. If you replace boiler and get compliant, they'll want to change everything. Including your HW cylinder. To get your guarantee you'll also be pressed into forking out excessive money for a pressure flush.

I would avoid a pressurised system if possible. Theyre less reliable and put a lot more stress on joints, heat exchanger, rads, etc.

NT

Converting an old system from vented to unvented may indeed cause problems.

But I don't think it's fair to extrapolate that to new systems. After all, they run at a lower pressure than mains cold water systems - and the joints etc. cope with that perfectly adequately. Unvented systems also don't suffer from ills like pump-over which seem to beset many vented systems.

It's a Glow Worm KFB50. It's had a new fan, been serviced, new pilot jet, new thermistor, refurb control board, had the pressure retwiddled and all sorts.

It doesn't light reliably (spark ignition just sparks indefinitely) unless the cover is left slightly propped open (which I know is somewhat dodgy - but it's in a well ventilated kitchen with a CO alarm right next to it). and now it's stopped even that. So it's time to go, I think.

The cheapest way would be to find someone replacing a boiler of a similar type which is working but being replaced for other reasons (e.g general refurb) and fit that. As it would be of comparable age, regs would only be an issue if anyone could prove when it was done...

There may be something wrong with the spark gap - which should be fixable. My Baxi Solo won't fire if the two screws holding the outer casing on are done up tight. I presume that they distort something slightly and screw up the spark gap. Slacken them just a bit, and it's fine!

Quite a few models permit (cf require) the use of a vented primary. Including Keston and Poxi-Batterton.

Interesting - thanks. So it may be possible to replace the boiler with a modern one without *too* much upheaval. The system would still need TRVs and some way of achieving a boiler interlock, though.

Baxi Solo 2 or 3? I've had a devil of a time with a 2 which would intermittently stop lighting. Replacing the pilot injector and ignition electrode seemed to fix it but then it played up again. Replacing the insulation on the EHT cable seemes to have fixed it (for now: fingers crossed, salt over shoulder, watch out you chickens and goats)

Maybe a similar problem with the OP's boiler?

Possibly but the whole pilot injector assembly has been replaced, as has the themocouple and the EHT wire from the board to the electrode... although saying that, that was about a year ago and it has worked well enough in the meantime (albeit propped slightly open) so conceivably something else could be going wrong *again* now!

Neither! Just a Solo - I suppose it would be a Solo 1, except that they didn't start numbering them until the Solo 2!

Yes. No problem, although not all models are suitable. My last house had an condensing Ideal Icos on a vented system. However, a sealed system is superior, and I would advise taking the opportunity to change over.

I see this as an advantage of the sealed system. Better have the radiators/valves etc. blow right now, with a plumber in the building. If the sealed system at 2 bar causes a leak, there is only a few months left at atmospheric pressure, when they might start leaking during Christmas dinner or when you're off on holiday.

Christian.

The current system already has heating system interlock, according to the description.

What it might not have, and would need if not, is a cylinder thermostat and fully independently controlled pumped primary circuit to the coil.

Christian.

I'm not sure how you have deduced that. He has said that it is a 20-year-old boiler, and the description says: "She currently has radiators without TRVs, a wall stat, an all-in-one pumped mixer shower and the aforementioned old-standard (no integral anything) boiler."

I'd put my money on that being a gravity HW and pumped CH system, with no valves and no cylinder stat. If so, it doesn't even provide heating interlock since the boiler will continue to cycle on its own stat after the room stat has turned the pump off.

Or a 2-port zone valve and cyl stat to convert it to C-Plan.

C-Plan does not comply with building regulations for a gas/oil boiler, as the hot water circulation is unpumped. Although a worthwhile addition to an existing system, it would have to be replaced upon boiler replacement.

Christian.

In that case, even more extensive mods would be needed if it *is* a gravity HW system.

It is easy to modify C Plan by adding an additional pump on the hot water side. Alternatively, most modernish boilers can have the gravity hot water capped off and have S/Y on the heating side. Check first, though, as some boilers require a reliable gravity circuit for heat dumping.

Christian.

FWIW it does have a cylinder stat as well as the wall stat, a pump and a three position valve.

I *think* if boilers are still available that will run a vented system while not containing a pump or being at mains pressure then that will be a drop in replacement. TRVs are probably worth doing at the same time while the system is drained and about to get a new shot of inhibitor...