Back boiler - like-for-like replacement?

What's the current state of play for replacing back boilers with another back boiler? I seem to remember hearing that the rule requiring condensing boilers would kill back boilers off.
My mother has a back boiler which is nearing the end of its useful life. There is nowhere convenient to put a wall-mounted boiler without redoing the kitchen. Any chance of her getting another back boiler? I also remember that there were some exemptions from the condensing-boiler requirement.
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"Martin Pentreath" wrote:

My understanding as a non-plumber is that your mother may be able to have a like-for-like replacement if the installation qualifies under the exemption procedure, that is, if installation of a condensing boiler instead of a non-condensing boiler is impractical or too costly. See <http://www.communities.gov.uk/index.asp?id31464> or just Google for exemption procedure back boiler.
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On 29 Dec 2006 15:48:47 -0800, "Martin Pentreath"

A great many people are in the same position with faithful back boilers giving up the ghost and needing replacement.
As has been said there may be a case for doing it in an above board manner, but it may be a case of finding a friendly plumber/corgi who does not think much of the regulations and does as he has always done, using experience.
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"EricP" wrote:

Could be a problem when it comes to sell the property if someone queries evidence of exemption.
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Just going through that now. Seems to be solicitors making themselves seem busy/covering their arses more than anything.
Demanding paperwork on 16 year old windows and 15 year old kitchens.
Problems seemed to vanish when told to go away. :))
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Many people don't like back boilers and want them out. They can hinder a sale.
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most combi boilers have vertical flues now with many elbow/bend options, dont bother with the expensive manufacturers roof slate and use a selkirk flashing....biggest problem i find is getting a suitable waste for the condensate when they are sited in the loft...dont forget the loft area up to the boiler will need boarding, a fixed light and a ladder up to the loft.....otherwise when your super efficient boiler gives up the ghost the service engineer may refuse to repair..

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The soil pipe usually rises in the loft. It can be teed into this. If no facility for a condensate waste then buy an Amtos boiler. They are condensing boiler that don't need a drain. <http://www.atmos.uk.com/product_group.asp?section 0200130005>
Top quality boilers - RR quality and very well designed. Plenty of UK dealers.
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From my understanding of "two Jags" rules, it doesn't matter whether there is anywhere "convenient" for the new boiler or not. There is a points system and if you score "x" number of points you may qualify for an exemption and be able to replace the existing back-boiler with a new back-boiler. If, however, you "fail" the test, you'll have no choice but to have a condensing boiler installed.
Having said that, you don't really want to stay with a back boiler unless you really have to because they are so inefficient. Our old one was something like 65% efficient, as opposed to the 90-odd percentage efficiency of the new condensing boiler. The cost of gas being what it is, it's well worth trying to overcome the obstacles of positioning a new boiler. We had our new boiler installed in the loft with the condensate drain poking out between a couple of slates, so that the condensate just dribbles over a tile or two, down into the gutter, and away.
JellyBelly
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JellyBelly wrote:

I'd second that. Loft installation is the way to go (assuming you have a gable end wall - probably a bit more tricky to fit the flue otherwise) Then it's out of the way and silent. Jon.
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I had this conversation with the tame plumber I'd found to fix our boiler the other day when it gave up the ghost a couple of days before Xmas.
I'd like to replace the current backboiler with a loft mounted condensing model (I also want to reclaim the room used for the airing cupboard/hot water tank but have a fear of combis from past experience (ie. crap ones)).
plumber wasn't keen claiming that a) I'd need a vertical flue which narrows the range drastically and b) it gets too cold up there so the frost stat would been it would run so often in winter that it would wipe out a lot of the efficiency gains.
Comments from people who have done this?
I can imagine building some sort of "shed" that is insulated a bit to help with the later problem (loft is currently just slate - no felt or anything).
Darren
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JellyBelly wrote:

I've never seen any convincing argument that condensing *systems* are more efficient in real terms.
I don't doubt that the *boilers* may be more efficient in terms of gas energy in vs hot water energy out, but that ignores the system such a boiler is used in.
With recommendations that a certain percentage of radiators have no TRV, in order to ensure the < 60 degC water-return temperature, then heat is being lost by the system in order to run 'efficiently'. That this waste heat is kept in-house in some way is no different to the case of my back-boiler's pilot-light. Not only keeping the boiler warm ready for the next burn-cycle, the chimney stack is in the centre of the house, adjacent to four rooms and the airing cupboard. I doubt any heat at all from the pilot gets out of the house.
We now have the silly system that DHW tanks are so well insulated that airing cupbords need radiators in them! What was 'lost heat' is now having to be supplied by the 'efficient' condensing-boiler system!
How many of these condensing systems are set up correctly?
My MiL had one fitted two years ago. The boiler return-water is scalding hot and I doubt very much if the boiler is working in the 'condensing' mode. Turning the temperature down causes the boiler to short-cycle.
I could spend a couple of days with a non-contact thermometer getting it all set up, but MiL is 'eccentric' and wouldn't welcome the intrusion. It's easier to leave things be.

I'm not sure it is. My kitchen is about a foot longer and wider than my arm-span. By the time the appliances have taken up the floor-space, there is precious little floor-room left. All storage has to be in the wall-cupboards, and getting rid of one for a condensing boiler would be a considerable loss.
With W-shaped roof supports taking up much room in the loft, mounting a condensing boiler on the flank wall, at the opposite end to the hatch, means long pipe runs, and access that would be difficult even for a fit person.
The 'dead space' in my house, ideal for a boiler, is where the current one is; but apparently I've got to play some kind of stupid game in order to get one according to the 'regulations'.
The man who last serviced my boiler, which is now 27 years old, said his dad had one exactly the same that was 43 years old and in perfect working order. I'll stick with what I've got.
--

Frank

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On 2006-12-31 11:23:14 +0000, Frank Lee Speke-King

That's not correct. You are missing the point that the majority of condensing boilers modulate the burner to reduce output and favour a low return temperature.

There isn't waste heat....

Most of the inefficiency of this type of boiler arises from heat going out through the flue.
I would agree with you that the pilot is a second order effect. A few years ago on the steps to increasing requirements for boiler efficiency, there was a requirement for better than 78% (IIRC) SEDBUK efficiency. Quite a number of products that were just over and that had had pilots were re-engineered with electronic ignition to bring them under the limit. I believe there's about a 3-4% or so difference.

Hmmm.....
Ah that's something else.

There is a common misconception here. There is not a sudden arrival at orgasm or Nirvana when "condensing mode" happens. What actually happens is an increase in efficiency with reducing return temperature all the way down. At the dew point, around 54 degrees, the *rate* of improvement increases. It is not a step function.
Is the boiler a modulating type? If it is, and is short cycling then something is wrong.

Something else again.

I can see your point, and in this respect, the exemptions on points in the building regulations don't address these practical issues very well.

Which when one considers the additional requirements to provide safe accesses such as boarding and rails for servicing, can become a challenge.

You can run through the points system check and may be able to achieve enough that fitting a wall mount condensing boiler is not a requirement according to the rules.
I did an exercise of this for my parents house (backboiler in centre of house) and it was possible to achieve the minimum points requirement.

There's no requirement to change it out.
However, rather than trying to justify no having a condensing boiler on grounds that are not really valid, it would be interesting to know if some enterprising manufacturer has made or is planning to make a condensing back boiler that fits the footprint of existing models at a reasonable price. I suspect in many cases a condensate pump would be needed in order to handle that aspect conveniently, but this should be workable. It ought to even be possible to arrange air intake and flue to be concentric and run up a flexible liner to a roof terminal. This would have the advantage of being able to do away with the room vent for air supply to a conventional boiler. Considering the installed base of back boilers, which will eventually become uneconomic to repair, this should be an interesting propostion.
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Andy Hall wrote:

Many thanks for your helpful reply to my not necessarily well worded posting; but essentially I was saying that the efficiencies quoted for condensing boilers could be more imaginary than real, for some practical cases.
I'd be very grateful if you could indicate the sort of things that you put in to the 'points' exercise for your parent's situation.
I'd be glad of the information against the day my back boiler goes belly-up - it pays to be prepared!
--

Frank

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On 2007-01-01 11:43:57 +0000, Frank Lee Speke-King

Here's the starting point, and the following page.
http://www.communities.gov.uk/index.asp?id31464
For their case, the points totted up as follows. Remember that the existing is a back boiler behind a fireplace in the lounge and is located in the middle of the house:
Property type - others, fuel natural gas: 590 points
New boiler in different room? Yes. 350 points
of the two possible places for installation, one would require an extended flue (>2m); the other would require a condensate pump. These are scored with 200 or 100 respectively.
Either takes the points total to > 1000 which is the exemption threshold.
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They are not imaginary at all. They are very real.

It ios best to get rid, for many reasons mentioned. Try the loft with an Atmos boiler.
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On 29 Dec 2006 15:48:47 -0800, "Martin Pentreath"

Why bother? Over a few years the savings in running costs from a condensing boiler, let alone the lower capital costs compared to a back boiler would probably pay for a new kitchen.
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On Fri, 29 Dec 2006 15:48:47 -0800, Martin Pentreath wrote:

As people have said there is an exemption procedure for replacing a gas (or oil) back boiler unit with a similar model, the exemption procedure is usually possible for flats with BBUs.
If you or your installer contact building control they may be able to argue the case for a non condensing unit on a one off case basis with the officer, especially if they exceed the minumum standards in other respects such as insulation and controls.
It might be possible to get a condensing BBU but they are likely to be very expensive. Indeed the BBU replacement whether conventional or condensing will probably cost more than a top of the range wall hung unit.
It all comes down to weighing up the different approaches and seeing which looks the least unattractive. (There will never be a really nice option when replacing a BBU).
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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