Condensing boiler flue

I am contemplating the inevitable replacement of my boiler with a new condensing one (not combi).
I guess the flue could be a problem, as it would have to be on a gable end, which is only 1m from the boundary with my neighbour. I presume the flue would have to be extended up above roof height. This sounds expensive, if it can be done at all.
Has anybody else dealt with this?
Chris
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Chris J Dixon Nottingham UK
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wrote:

It depends on the make of the boiler. Flue systems for some, especially the concentric types, are proprietary and can become expensive if you need any substantial length of them.
However, there are makes such as Keston which have a flue system based on 50mm high temperature plastic waste pipe. The boiler comes with the terminal fittings for the end and then you buy the pipework and other fittings pretty cheaply from a plumber's merchant like Plumbcenter or a host of others.
Other boilers may have adaptors as an option that can be fitted to the boiler instead of the regular flue system to convert to a twin 50mm tube arrangement. I have a MAN Micromat which has that as an optional component.
There is enormous flexibility, based on a few rules about the running of such a flue system - it can be inside or outside the house and can run a considerable distance. You don't necessarily even have to run the pipes in parallel to a common point since this boiler type is fan operated anyway.
There are regulations around the siting of flues and you can find useful information if you download boiler installation instructions. Taking Keston again as an example, they have downloadable PDFs for all of their boilers. There are generic rules and then manufacturers may have additions and alternatives which take precedence.
Another alternative is to have a dual or concentric flue running up inside the house and then through the roof. There are special sealing adaptors which replace a tile to do this.
Generally you will find that manufacturer's technical departments are really helpful with advice. It can be useful to make a reasonably dimensioned set of sketches of the property and the environment to help with this.
Even if you do comply with the regulations, it is neighbourly to direct the flue up and away from their property if you can. As you probably know, condensing boilers do produce a plume of water vapour under certain operating conditions although this is not as big a deal as some people would suggest. You can use 135 degree elbows in the pipework to direct the output where you want.
Don't forget that you also need to take account of disposing of the condensate. Since this is mildly acidic, it needs to be piped away from the boiler in plastic pipe (overflow is commonly used) and led to a drain outside the property. Alternatively it can be run into an existing waste system via a trap.
.andy
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Will it take plastic drain pipe?

The air intake tube can be just to outside near the boiler and the exhaust 40, 50 metres away to avoid the plume
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Yes. There are a number of optional adaptor fittings which can be used in place of the standard concentric elbow and pipe 125mm/80mm arrangement. One is a fitting which has two sockets for 50mm tube and the design rules are then similar to Keston's
I didn't bother with this because the standard flue was fine for my application. In any case with this model, even when heavily condensing under high burn rate, very little water vapour plume exits from the flue. The collection arrangements of the heat exchanger etc. work very effectively at collecting and delivering to the drain.

.andy
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In my Experiance Keston boilers are ok when working but a bastard to fix.

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On Sun, 16 Nov 2003 21:13:18 +0000, boilerman wrote:

I'm genuinely interested to know on how this comes about? ? Difficulty in obtaining parts? It can't be limited access to components there is loads of room in the case. ?Is it difficulty in diagnosis? Though I can't see why it's harder than other boilers. So far I have not had to fix one of these as yet.
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wrote:

Fix what? As regular readers will know, we put two Celsius boilers in our church in Summer 2001 (the fluing and remote wiring of panel lights made them ideal for our needs) and they have been pretty good though not 100% (at least twin boilers provide redundancy). Keston replaced the PCB's under warranty to overcome the fluctuating pump speed problem discussed recently, and I've replaced both igniters, one condensate trap and one flue hose. The encouraging thing is that in each case the replacements have been better made than the originals which suggests that they are learning from in-use experience.
The spares available through HRPC is not bad (1-2 days) but I can understand why your average domestic installer would prefer something more mainstream with off-the-shelf parts.
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So for two boiler that are barely 2 years old the've had quite a few parts. Not Good. Surely its better to fit boilers that need less maintenance.
Many installers dont realise the burner has to come out from the top, and they get fitted either with pipework running above the boiler or they get installed too close too the ceiling of the boiler room, making the burner impossible to remove.
Boilerman

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parts.
The Glow Worm's is removed from the front.
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Boilerman

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wrote:

I suspect that they were early production - as I said, all the replacement parts have been better, presumably in the light of field experience. I've no regrets, and in this particular application there was no comparable alternative
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On Tue, 18 Nov 2003 20:54:09 +0000, boilerman wrote:

This would be a case of plain illiteracy. The manual clearly indicates the general layout of components.
There is no way you could install the boiler without adequate top clearance: Firstly the intake and flue spigots are at the top and the shortest distance you could turn the pipes sidewaye in would be at least 100mm. Secondly the cover comes forward and then the combustion fan comes off giving ample room for the burner removal even if the above point were false.
Are you sure you are not confusing a Keston Celsius 25 with some other model or even a different make?
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Ed - Ian Nutt here. Just to let you know I replaced the diaphragm in the diverter valve and it works a treat. Thanks a lot for your time, mate.
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