Boiler in cellar with chimney flue

[supagav]

Hello,

Is it possible to replace an old boiler system in a cellar (vented with flue through chimney) with a combi boiler system flued in the same way? I have read some installation guides that suggest a maximum vertical flue of 20 metres (which would be ample) but does that count if it is an exisitng flue through the chimney?

Thanks

 

[John506]

Hey, I was doing this in college the other day (on my 3rd year of plumbing)

If the flue is too high, the gases will cool down halfway up and won't rise out the top of it, and come back down (spillage), then the flame in the boiler will start to take the oxygen out of the Carbon Dioxide in the flue gases, which will turn it into Carbon Monoxide, and unless you have adequate ventiliation (guessing you don't seems it is a cellar) it's pretty dangerous.

If the flue is too low.... without reading over my sheets, I can't remember.

It all depends on the power of the boiler, I haven't learnt the formula yet for working out the height of flues.

Hopefully someone more experienced will finish this off....

 

[Gasguru]

Band A boilers utilise high pressure fans so flue lenghts are not usually a limiting factor. You could start by looking at Halstead boilers....they offer a flexible flue liner however, it is an extortionate cost and Halstead are not particularly popular. There may be other manufacturers offering similar solutions.

Most boilers I encounter in basements have a high Kw output since the properties are of significant size....ie a combi would be totally unsuitable.

What's the existing boiler?

 

[sooey]

I haven't learnt the formula yet for working out the height of flues.

Stephen Hawking's is still trying to get his head round that one as well.

 

[supagav]

Thanks for the replies. The current boiler is a Vulcan Continental which I think must have seen a good 30 years of service! My house isn't very big, just a terrace house with a cellar.

It is currently a vented system but I would ideally like a sealed system. If I have to move the boiler it would be a big job because it would have to be moved to the first floor. Having said that, if the only boilers available are expensive, it could be six of one and half a dozen of the other.

Cheers

 

[simond]

Worcester are about to launch a new plastic flue liner system.

 

[namsag]

Move position of boiler even to loft. It will work out cheaper and a lot less hassle than trying to find a flue system and boiler that can go up a chimney

 

[spacethegas]

+ you need to think about condensate disposal.

 

[doitall]

Broag can go on a flue liner, with a separate air intake.

 

[supagav]

Thanks for the advise.

It shouldn't be a problem drain the condensate from the cellar because there is drainage down there for a washing machine.

I guess the next stage is to get some quotes on the various options and see how I go.