New Gas Boiler again

[Roger]

I have a 20 years old Glow-worm Spacesaver wall boiler which works fine, providing pumped CH and gravity DHW. B/Gas 3 star engineers keep telling me the they can "no longer guarantee to be able to source spares"...ie a sales ploy to sell a new boiler. Our local council are supplying discounted high efficiency boilers as a greening initiative, but I reckon the bill will be £2k with fitting and maybe mods to the exisiting system. Any of you experts got any impartial advice ? My gut instinct is to try and source spares for my existing boiler to keep it going as long as possible. What do you think.?

[Christian McArdle]

Keep it going. Start putting money into a replacement fund for when it finally breaks down terminally. Don't bother with boiler insurance. If you hadn't paid for it and just put the cash into a bank account, you'd probably already have saved enough for a new boiler...

Christian.

[Set Square]

I would update the system at a time of *my* choosing, and certainly *not* employ BG to do it.

It's pretty certainly a sales ploy to try to sell you a new boiler - although there *may* be a risk of not being able to get spares at some point, which would leave your stranded. Meanwhile BG still seem willing to take your money for a maintenance contract - which would be fraud if they

*knew* they couldn't get spares. [There are lots of on-line sources of boiler spares. It wouldn't do any harm to line up possible sources of PCBs (if applicable), fans (if applicable), thermostats, gas valves etc.]

Updating your system will cost quite a lot of money. Not only will you need a new boiler but you will also need to modify the pipework and add a lot of controls - zone valves, tank stat, TRVs, etc. to comply with the latest regs. BUT, having done it, you will save a *lot* of fuel. Modern boilers are much more efficient than 20-year-old models and, coupled with better controls, you'll achieve the same or better comfort levels with a lot less gas.

So it *is* worth doing - but you can choose your own time to do it.

[Harvey Van Sickle]

On 12 Jan 2005, Set Square wrote

-snip-

Agreed.

As an aside, I've just had a conversation with my boiler service guy (very local -- I know him well, as he lives three doors away), who was saying that from (April?), new installations will have to use condensing boilers, and conventional boilers like mine (which is 7 or 8 years old) will no longer be installed.

He understands the efficiency reasoning behind this -- although, as he noted, placing a condensing boiler on an old system can reduce the efficiency to the point where it's not actually condensing -- but mentioned that he's quite busy at the moment installing conventional boilers for people who want to beat the deadline for the new regs.

[Jim Alexander]

Not a fan of BG service but after 20 years they may have a point. If you decide to go the new boiler route which really means new system route you have a choice in the open market. No need to accept BGs offer. Sadly its a hard lesson, the BG money is down the drain now, only you can decide if the unlimited call-out peace of mind was worth it.

My view would be that the existing boiler is written down and expenditure beyond the odd thermocouple isn't worth it. Start planning now for a replacement, but not during the winter heating season.

Don't know where BG get this unlimited call-out idea from, unless it is their own duff maitenance. On balance, most appliances of any description these days don't require unlimited call-outs, so the BG offer can't be good value. Bank the savings.

Jim A

[Jim Alexander]

Not a fan of BG service but after 20 years they may have a point. If you decide to go the new boiler route which really means new system route you have a choice in the open market. No need to accept BGs offer. Sadly its a hard lesson, the BG money is down the drain now, only you can decide if the unlimited call-out peace of mind was worth it.

My view would be that the existing boiler is already written down and expenditure beyond the odd thermocouple isn't worth it. Start planning now for a replacement, but not during the winter heating season.

Don't know where BG get this unlimited call-out idea from, unless it is their own duff maitenance. On balance, most appliances of any description these days don't require unlimited call-outs, so the BG offer can't be good value. Suggest you bank the savings next time.

Jim A

[Set Square]

AIUI, boilers will have to be capable of at least a certain efficiency level - which condensing boilers can meet more easily. I'm not sure that it's necessarily *impossible* to meet with a non-condensing boiler?

*Can* but not necessarily *does*. Systems designed to run at a high radiator temperature won't allow the boiler the condense when running at that temperature. But this will only happen in very cold weather. In milder conditions, the rads can run cooler - but be on more of the time - which *will* allow the boiler to condense.

[Harvey Van Sickle]

On 12 Jan 2005, Set Square wrote

That would be interesting to know -- but from my friend's statement it sounded as if the manufacturers werent' going down that road. (He mentioned that the only non-condensing boiler which was currently available without jumping through hoops was a floor-standing rather than wall-mounted model.)

Yes, right: he was quite clear that it was system-dependent. He was just making the point that increased efficiency depends on more than simply hooking up a condensing boiler to all existing systems.

[IMM]

Not so. Modern condesning boilers have load compenstion modulating control to lower the return temperaure to the building heat load. Over 90% of the time a normal system will be on part load, so not really an issue. Maker have designed boioer for the replacement market.

Stupid idea, condensing boilers are well worth it over regular boilers. They are virtually the same, only one has a larger heat exchanger and a condensate drain.....and saves lots of gas.

[IMM]

Not so. Just get the right boiler and simple replacement and efficiencies far greater than before.

[Set Square]

Having said that, a new boiler - condensing or not - is going to be a damn sight more efficient than a 20-year-old model anyway!

Personally, I wouldn't want it *too* efficient. Stray heat from my boiler is the *only* heat I curently have in my utility room!

[IMM]

SEDBUK has the best regular at about 80.5%. The "peak" efficiency can be over 90%.

If you engineer the system to get the most from a regular boiler you can be in condensing boiler efficiencies. But you have to know what you are doing. A regular boiler is designed "not" to condense.

1. A blending valve is fitted on the flow and return ensuring the boiler return never gets below say about 55C, which below condensing occurs
2. The boiler stat is set to 10C above so at 65C

1. The cylinder coil and rads are designed and sized for this 10C differential and flow of 65C and return of 55C

Doing the above will improve a regular boilers efficiency substantially. Just having the blending valve and setting the boiler to 65C will do wonders, as in most homes the rads are oversized for most of the operation time. They are sized for the worst case example of -1 to -3C outside. If it is really cold then turn the boiler stat up to full, then back down to

65C when it warms up outside. Simple to do, will protect the boiler from condensation and improve efficiency.

[Roger]

Hi guys...thanks very much for the advice....much appreciated. For information, I have just spoken to tech support at Glow-worm who assure me that all spares are available for this boiler and will be for the foreseeable! His comment was that BG want me to replace the boiler before it starts giving problems and costing BG money. (ie I'm on a fixed price contract). His advice is to run it until it drops, which could be years. He also said "there is b***er all to go wrong in those simple old boilers, unlike the new condensing jobbers which have hundreds of parts to go wrong!" So I'll stay where I am........ Thanks again Roger

[IMM]

Bills will drop by about 40%. It is worth keeping this boiler for a while and see if the condensers drop in price after April.

[IMM]

New non-condensing boilers have just as many parts to go wrong. It is worth your while doing the figures on payback as you gas bill will drop like a stone. The techie mans opinion is well, just his opinion, not the definitive way to go.

A new modulating boiler will give superior comfort condistions and give greater DHW recovery. So, you also have greater advantages in living with a new system.

[Andrew Gabriel]

The area where they are significantly more efficient is less waste heat going out of the flue as steam, which probably does little to heat your utility room unless there's a long length of exposed flue. It's interesting to watch the condensate trickling out of a condensing boiler and think to yourself that you used to be wasting the energy required to boil all that away and send it up the flue.

You can always have an extra radiator fitted when the boiler is replaced. (If you have any radiators which are currently too small for their rooms, you should think about upgrading those when you switch to a condensing boiler, and you might be able to swap a small one which becomes spare into the utility room.)

[Ian Middleton]

Not convinced of the economics of boiler replacement, other than if terminal. A mate of mine had his old back boiler replaced and pipework modified for fully pumped wall mounted jobby, cost £2.5K, job nicely done but bills dropped from about £220 a year to £170 a year which gives a 50 year payback time !!!

[IMM]

Don't reuse rads. They contain rust and the likes. Not worth it as they are so cheap..

[Set Square]

That's a very valid point - even allowing for a rapid rise in gas prices, which will shorten the payback period a bit.

[IMM]

I'm sure this man didn't change a back boiler just to save £50 a year. He did it to get rid of the thing from his living room. Then there is the comfort that a new boiler gives.