central heating upgrade questions

[brian mitchell]

Hello,

My flat is heated by an old Ideal gas boiler, I hesitate to say exactly how old but we're talking decades. It probably has an efficiency rating measured in negative numbers but has never once failed. That's important to me. However, the engineer who has just completed its annual service (basically, sweeping the debris from underneath the burners) tells me it's too old for him to continue servicing it and it needs replacing. That I can understand, but he also says that the radiators and the copper piping under the floor have to go as they no longer conform to EU standards, and this is what I want advice on.

The piping, hot water storage tank, cold water tank, etc were installed circa 1982 for an earlier boiler. Two of the radiators are of that vintage, others have been replaced. The piping includes two motorised valves, one of which has had to have its motor replaced. The electrics are ultra-simple, non-digital, non-timed, room/tank thermostat driven and have also never failed. The gas supply is also copper from the same initial installation. Oh, and one change of pump. Is it correct that all of this will have to be ripped out and replaced?

I've gathered that all newly installed domestic boilers have to be of the high efficiency condensing type. Is this universally true? I'm assuming that these only run on mains water pressure; is that also true, or are there low pressure systems still available? I'm aso being told that the radiators must have thermostatic valves, the point of which I cannot see. The present boiler is housed outside the (ground floor) flat in what used to be an outside toilet, with the storage and header tank above. Replacing that wouldn't cause major upset but I'm loathe to have all the floors lifted if it's not actually necessary. There's also the not inconsiderable matter of price.

I'd be grateful if someone could clue me in on the current legal situation (how much is mandatory, how much merely advisory) and generally give their opinion on what's best to do.

Many thanks,

brian mitchell

[Dave Liquorice]

If it really is 20 or more years old it probably is worth replacing with a more effcient model.

Do any of the parts, valve, radiators, pipework leak? Has the system got inhibitor in it? If it ain't broke don't fix it!

Don't confuse a condensing boiler with a combination (aka combi) boiler.

A condensing boiler is a type constructed to use the lower temperature return water to condense some of the water vapour out of the flue gases, recovering the latent heat of evaporation in the process. This improves effciency.

A combi boiler is a boiler that heats the radiator circuit and the domestic hot water directly. You do get mains pressure hot water but unless you get a fairly hefty boiler at rather slow flow rates if you want decent hot water.

A combi boiler may also be a condensing type (most are these days). A condensing boiler does not have to be a combi.

Enables you to set individual rooms at a temperature suitable for their use. No point in heating the spare bedroom that is not in use to normal temperatures for instance.

IMHO your system could do with a refurbishment. New condensing boiler (no need for a combi) and decent control system could well see a 50% saving in your gas bill. I'd fit a programable room thermostat and thermostatic valves to radiators not in the main living/use areas, such as bed and spare rooms along with some form of timer and thermostat on the HW cylinder. Get as much insulation around that HW clinder as you can even if it is already foam lagged.

[Roger Mills]

As others have said, your old boiler could keep you going for a number of years yet - so do your own research on the availability of spares.

If you *do* replace the boiler, the new one needs to conform to current efficiency standards - which means (with very few exceptions) that it needs to be a condensing boiler. Also, the controls will have to be updated so that each radiator is turned off when its room is hot enough, and the whole lot is turned off when the primary room stat is satisfied. So you'll need TRVs on all but one radiator, and the working of your motorised valves will need to be checked - and possibly updated.

But I see no reason whatsoever to change the radiators and pipes as long as they are sound - and any reference to 'EU Regs' is cobblers as far as I am aware. The only note of caution here is that, for a condensing boiler to run at optimal efficiency, the flow temperature needs to be lower, so you need larger (or perhaps just finned, of the same size) radiators to get the same heat output. However, if the insulation of the house (loft insulation, cavity wall insulation, double glazing, etc.) has been improved since the system was installed, chances are that the radiators are over-sized for the current heat losses anyway, and will still be ok with a condensing boiler.

A new boiler would almost certainly use a sealed/non-vented/pressurised (*not* mains pressure!) system - but that's not a big deal - you just install a pressure vessel, filling loop and pressure relief valve and get rid of the F&E tank. Converting to pressurised will show up any weaknesses in the pipework, which will need fixing. Old radiator valves sometimes leak under these circumstances, but you'll be fitting new TRVs anyway. If you go down this route, I would also replace the lockshield valves - preferably with ones which have a drain-off facility.

However, I would think carefully before doing *anything*. A new boiler will save gas - but the break-even point will be many years down-stream - possibly beyond the life-span of the new boiler!

[The Medway Handyman]

Wouldn't be those lying toerags from British Gas by any chance?

[Harry Bloomfield]

brian mitchell pretended :

Hello.

As others have said, do a check round yourself to see what spares might be available for the old boiler - they are very simple and basic, nothing much to go wrong. 'Stat, gas valve and ignition/ pilot check you can get these and it could run for ever. Has it ever needed anything, other than cleaning out?

Modern condensing ones are much more complicated and cost more to repair and will not last for as long as the simple boiler you have.

Fitting a new condensing boiler, is not necessarily a reason to replace the rest of the system, unless there is good reason, such as rusted radiators and leaks. You can get condensing boilers which work in exactly the same way as your present boiler - using the existing header tank and hot water cylinder. As an alternative to the header tank, a sealed system could be installed - basically the system is filled via a filling loop from the mains and a 'tank' with a diaphragm in the middle and pressurised air above it, forms the system pressure (1 to 2bar). These are not very tolerant of leaks and the pressure can disappear rapidly, needing them to be topped up again from the mains - unlike an old style header tank which is automatic.

TRV's are probably worth fitting, but can be retro fitted to an old system.

Our heating system is 28 years old, header tank type and 18 months ago decided to replace the boiler for a modern condensing type. All that was changed was the boiler, room stat, pump and CH/HW valve. None of the latter items were essential, but they were done anyway. In the 28 years, we have installed double glazing, cavity wall insulation and etc. so our energy requirement have decreased quite a way.

[Clot]

A snip

Well? unless you use it as your airing cupboard and it heats your bathroom.

[Clot]

That was my immediate thought!

[David]

Just out of interest, what new boiler did you get?

[John Rumm]

If its something like a balanced flue Mexico - then it is probably something like 65 - 70% efficent. A modern one will take you to 90%+, however you will need to translate that into a proportion of your annual gas bill to know if changing it makes sound economics.

That does not really make sense. Is he going to forget how to sweep? If it breaks and needs spares then that may be a different matter, but even then, as others have said, there is a fair chance many items are still available.

Sounds like bull...

If your new boiler is a sealed system type, then you could lose the CH header tank. If you go for a combi boiler then you could do away with the other tanks. However there are pros and cons to doing this, and its certainly not a requirement.

As long as its traditional two pipe system (i.e. separate flow and return pipes to each rad) then the pipes should be fine.

Just about. There is a points based system that lets you assess if you qualify for an exception. Unless you have a back boiler and live in a terrace then chances are you won't.

Its also important not to get too bogged down in reliability of condensing vs conventional boilers. Its true that a cast iron lump such as you have will probably be more reliable than a highly complex modern boiler with electronics and fans etc. However you can't buy boilers like yours any more. Even modern non condensers will have equal complexity, and electronics etc, and are unlikely to be much different in overall reliability. So if changing you may as well go for the technology that costs least to run.

Sealed systems are certainly more common, but some modern boilers will still run with a vented system. (IIRC Tim S was installing one in his current refurb project). However a sealed system is generally better IME.

This is true. The point being that it saves energy wastage once a room is warm enough - even if the heating needs to carry on for a bit to get other rooms up to temperature.

Indeed. I can't see a need for too much floor lifting. Keeping current pipes, adding TRVs, and swapping in whatever type f boiler you decide to go for. Pipes are unlikely to leak unless they already do - even if you do increase the pressure. Old lockshield rad valves may weep a bit - but often they are ok.

If changing you need:

HE Boiler

Controls upgraded to modern spec (TRVs, and a room stat)

If the house is over a certain size (large) then zoning of the heating into discrete areas

hot water cylinder may need better lagging than the current one. (if its as old as the rest of the system it may be time for a swap anyway)

Basic info on CH design:

on boilers:

[Chris J Dixon]

Surely the "mains pressure" refers only to the hot water output of a combi, which has already been well described. Whether sealed system or not, the radiators do not run at mains pressure.

Chris

[Dave Plowman (News)]

In this house they do. My mains pressure doesn't exceed the maximum recommended on the pressure gauge.

[Chris J Dixon]

Advantage Plowman ;-)

Chris

[Dave Plowman (News)]

If only. Pathetic mains pressure in this part of London. In the first floor bathroom I have mains cold to the basin for teeth cleaning etc. And the flow from that is no better than the hot from the tank fed storage hot water system. In the kitchen it was - but due to fitting a fancy mixer tap (high pressure only) had to fit a pump to the hot water to match the cold. ;-)

[John Rumm]

Depends on what you call mains pressure I suppose. Most sealed systems will run between 1 and 2.5 bar, with the pressure blow off valve set at

3 to 3.5 typically. Mains can be anything from 1 to 10 bar or more.

[PeterC]

From personal experience: fitting a combi puts mains pressure on the HW side; 45yo pipes near/above cooker might have been corroded a bit. After 2 pinhole leaks I re-plumbed all of it.

When the combi was fitted, I was left to change the LP valve in the flush to a HP one. This could have been disastrous for some one who didn't realise what might happen.

If the washing machine takes HW (unlikely nowadays), the inlet hose will be hot and at mains pressure (if the HW gets that far) and most are rated at =

[brian mitchell]

A lot of encouraging and informative replies. Thanks. One question more: if I do decide to change the boiler, how much can I do myself? Can I connect the gas to it and wire it all up, or must I get registered engineers (fitters?) to do the final bits? I did the original installation but things have changed since then, I know.

brian mitchell

[John Rumm]

If you can claim "competence" then you can do it all, alas there is no exact legal definition of what makes one competent. Personally I work on the basis if you can understand how to do all that is required in the instructions. You know how to safely decommission, purge, pressure drop test, and can make reliable soldered joints every time then there is little to worry about.

[Owain]

You can do all of it if you are "competent" in terms of gas, but you would have to (are supposed to) apply to Building Control for a certificate of compliance with Part L for the installation of a new boiler (and possibly Part P for wiring).

Owain

[Harry Bloomfield]

brian mitchell presented the following explanation :

You can do all the work, if you would describe yourself as competent and are doing the work for yourself.