A boiler shock

[Moo]

We've just had our twelve year old combi boiler serviced (not by British Gas!) and learned that the heat exchanger is on its last legs and should be replaced at a cost of £500, so that's going to be done next week.
BUT - we've also learned that because all new boilers are now the condensing sort, any eventual replacement boiler wouldn't be a simple matter of taking the old one out and plugging the new one in - it would have to go somewhere else.
At the moment the boiler is right in the middle of the building (discreetly hidden in the book room on the first floor) and vents up a (lined) chimney, but a new one would have to have a balanced flue to the outside. As the nearest outside wall is on the street, we guess that a vent there would be out of the question - listed, conservation area etc.
The only place that a new boiler could be installed would be in the (brick) shed at the end of the kitchen, which is a very long way away from its present site, and would presumably mean some pretty major re-routing of pipework (= pretty major cost!).

Please, can anyone come up with some words of comfort?

 

[philpjuk100]

Condensing boilers have a life expectancy of five years!! we had our 30/40 year old boiler replaced last year as replacement parts were not available,I was shocked to read in the Telegraph that heat exchangers will only last five years due to corrosion,the heating engineer who installed ours told us that replacement of a heat exchanger would not be viable even if spares would be available in five years time! He also pointed out that this short life is reflected in service/insurance premiums and that in five years more efficient boilers should be available. If I had known this I would have considered scrapping the old one more carefully.Good luck,check if any grants are available (we had a "warm front" grant).phil.

 

[Feltwell]

You can get condensing boilers that use a chimney as their flue Moo, but they're fairly rare and I'd imagine more expensive than a "normal" condensing boiler that, as you say, needs an external wall.

http://www.telegraph.co.uk/property...ff-Howells-DIY-advice-condensing-boilers.html

http://www.hwch.co.uk/kidd.html

When looking at sites for a new boiler bear in mind that you also need to have access to a drain - the condensate from the boiler must be connected to drain away to your waste water system, it's quite corrosive stuff. You can pump it through small bore piping if you have to, in order to reach a drain. The link below talks about that.

http://www.harwoodandassociates.co.uk/what-we-do/kidd-vhe-boilers/

I sincerely hope that condensing boilers last longer than 5 years, given that mine is 5 years old......

 

[jocelyn plummer]

Moo, what a blow--- many combi boilers installed around 2001 do seem to have lasted for up to 10-12 years with spare parts available until now. Although you have had one independent opinion it might be worth having a couple of other opinions about a possible rpelacement and its position ( so long as you don't have to pay out for the advice!!). Of course, the new heat exchanger should buy you another 5 years or more--- . We had a water softener gizmo fitted to the oil fired combi boiler that was installed at Foxgloves in 2003, reputedly to help ease the level of corrosion.
Rock and hard place stuff I.m afraid!

 

[Flyfisher]

I've read that condensate is corrosive but surely it's not beyond the wit of the designers to use a corrosive-proof material for the condenser?

A five-year lifetime for the whole boiler is ridiculous. The energy savings from the condenser would probably be outweighed by the army of plumbers driving around the country replacing them!

I wonder what the trading standards would say about such a thing. Surely a five-year serviceable lifetime for something as simple as a gas boiler cannot be considered as fit-for-purpose?

 

[Keithj]

'Tis a strange phenomenon, the law.

Condensing boilers were mandated to reduce waste of energy. So ban a boiler design that might last 40 years (our Essex one did), and force people to use a condensing one that burns 5% less fuel but only lasts 5 years. I hae me doots about whether or not that is "efficient" for anyone except the boiler manufacturers.

The quote to replace our Essex non-condensing one was something in the region of £10,000. We moved house.

 

[philpjuk100]

Will a water softener help? the water in the system is fed in with the "filling loop" with treated water and only gets fresh water if you have to top it up,and the corrosive condensate comes from the combustion process.Is there any way to extend the life of the heat exchanger? My old boiler had the tranformer on the pilot light igniter fail so I replaced it with an old motorcycle magneto fitted in the place that the old igniter had lived in,it was only needed to light the pilot light when I turned it off to save gas.But I replaced the boiler after adverse criticism "you are not qualified!" "dont mess with gas","we will all be killed" sort of thing and it now seems that replacement will now become a regular event.I would have been willing to pay a little more for a boiler with a longer life.It seems to be all part of the disposable way of life.At my first property I fitted the central heating with a "kit" system bought from an advert in "exchange and mart"(granada heating microbore system) before the days of corgi/gas safe,this was 35 years ago and looking at the flue last time I passed it still seems to be in use.phil.
I realise that fresh water on a combi system passes through the boiler and a water softener will prevent calcium deposits.

 

[worms]

Living in an area with very soft water (but very few people able to access a gas main!) I'm not aware of the heat exchangers lasting any longer than elsewhere.

 

[Juju]

I don't know anything about boilers except that ours is a combi boiler and was installed about 13 years ago and still seems ok every time it's serviced. A neighbour of ours moved their boiler to their front room and they've been allowed to install the pokey out flue on the outside wall on to the street (we don't have front gardens). They're not listed but it is a conservation area. I queried it with the council but they said it's ok...
Juju

 

[Feltwell]

Will a water softener help?

I've wondered that in the past, as we have a water softener. The plus side is obvious - less limescale deposits in the system, probably more of benefit to a combi where it's getting fresh water every time you run a tap, rather than a conventional boiler where it's the same old water with corrosion inhibitor going round and round.

But, softened water contains more salt than unsoftened water - you can taste it, hence why you don't use it for drinking (also certain health issues). Would that salt cause a faster corrosion rate? Would the inhibitor effectively stop it? Will a combi where there cannot be any inhibitor for the hot water side suffer as a result? I don't know.

One benefit for a conventional system is the effect on the hot water cylinder. When my old one went to the scrapyard, they cut the bottom off to tip the limescale out prior to weighing the copper - about 2 buckets worth of limescale came out, and that was after about 2 years of it being used with a water softener (and many more before without) - so how much it contained at it's peak, I dread to think! Now we have a water softener, hopefully it's not building up again.

Of course just living in a soft water area would be better still.

 

[Moo]

We, too, have a water softener - installed when we did the initial work on the house. However, I'm assured by the OH that the heat exchanger decay isn't caused by water, but just suffers from some sort of metal fatigue.
But why is it such an expensive piece of kit? £500 seems a bit steep for a spare part!

Thanks so much (again) for all the helpful advice. I find the prospect of replacing our faithful combi rather alarming - it will involve some pretty major disruption, not to mention the cost. So we're just hanging on with our fingers crossed that it won't happen too soon, and in the meantime following up those helpful links to the one that seems built to last.

BTW - which government should I blame for bringing in that ridiculous new regulation?

 

[d49xc]

Very soft water is exceptionally bad from you
It is associated with Stomach cancer.
I've believe this cancer has an higher incidence in soft water parts of the the UK - though I'd expect by now in this modern age they would be treating the water to try an alleviate it.
Some corrosive soft water can also eat away at the copper pipes and result in the copper content in parts per million in the water particularly at the hot tap being above the permitted limits

This is why the feed for the kitchen tap should always be taken off prior to the water softener - as this is the one most likely to be drunk from, used in food cooking etc.

I recall from my engineering days involved in de-salination plants in the middle east which take a gigantic amount to power to run that the raw output has a hardness factor of zero (ie 100% soft) so is actually lethal to drink - it has to be "modified".

£500 sounds sadly typical for a complex moulded stainless steel heat exchanger with various drillings and channels in it.
Combi's are much more complicated than the old style system boiler.

 

[Lime]

The heat exchanger is a major part.
However I am long past the time when I believed service "engineers" who proclaimed something was about to fail.
Ask to keep the part they replace and watch their face/s. :wink:
It can often be very uninspiring for your confidence.

The legislation follows an EU directive.

 

[Moo]

This is why the feed for the kitchen tap should always be taken off prior to the water softener - as this is the one most likely to be drunk from, used in food cooking etc.

We've got one of them in the kitchen.

Some corrosive soft water can also eat away at the copper pipes

How can I tell whether my softened water is the corrosive sort?

 

[Flyfisher]

I think there is some confusion here about condensing boilers corrosion and hard/soft water - the two things are entirely separate.

The condensate from a condensing boiler is a consequence of its greater efficiency. In a 'normal gas boiler the burning gas heats the water jacket through which water is circulated and thus heated. This is the hard or soft water being discussed. The burned gas exhaust then goes out the flue.

In a condensing boiler the burning gas also heats the water but the the exhaust gases are passed through a condenser before going out through the flue in the normal way. The condenser extracts a bit more heat from the exhaust gases, which is why these boilers are more efficient. So far so good.

But, the condenser reduces the temperature of the exhaust gases (that's where the extra energy comes from) to the point where the water vapour and other combustion products condense into a liquid. This is the 'condensate' that must be piped somewhere. Unfortunately, the combustion of the gas also produces various nitrogen-based chemicals and these combine with the condensed water to form nitric acid, among others. This is the corrosive agent that corrodes the condenser.

I still don't understand why a corrosion-resistant condenser can't be made - I presume it's an economic thing.

None of the above is affected by hard or soft water; that is an entirely different issue and apply regardless of the type of boiler.

 

[Feltwell]

It was more just limescale clogging things up that I was meaning FF.

Do you have lots of chalk in your water where you are? In Feltwell the whole village is supplied from a borehole and the water can be extremely cloudy from suspended chalk particles - I remember it being so bad at certain times that if you held a glass of water up you could barely see through it, it looked more like milk!

 

[Flyfisher]

We're on mains water and I haven't noticed any cloudiness in the water. But you're right about the chalk everywhere . . . half our house is built from the stuff and we have a large pit in the grounds where, alledgedly, it was excavated.

 

[Moo]

I've just had a thought -

What if, when our boiler finally turns its toes up, we were to install one of those Rayburns that heat the radiators and the water? How would The Regulators feel about it?

 

[Feltwell]

Plumbers are not in my good books today - well, one plumber anyway.

We found our boiler was leaking. After leaving several messages for our usual plumber - as gas is usually one thing I won't touch - with no reply, I decided to see if I could find the problem without taking the burner etc out. One boiler partially in bits later, and I find it's because he didn't put a hose clip back on the last time he serviced it :evil: .

 

[Moo]

Grrrrrrrrrr!