Flue reducer

[Bongo]

I'm looking to replace my stove, and have found one with the perfect heat output to room / boiler, but it has a 6" flue outlet. (We're heating a 63'x 12' widebeam with 3 radiators)Currently we have a 5" collar through the roof. Can I use a reducer between the stove and flue?

There don't seem to be many chandlers offering collars with a 6" internal dimension, is there a reason for this? thanks.

[Charlotte Burnett]

Yes, you can and a decent chandler will stock them. I have no idea why most botes use a 5" welded tube instead of the slot together 6" stuff used in houses, I'll guess that it is something to do with draw due to the reduced flue length. If your boat is a new build, I think that you should be using double skinned flue though - paging Rob BSS...

[blackrose]

Yes, you can use a reducer. The reason most boats don't use the slot together flues is that vibration and banging into lock walls, etc, may break the seals between the sections and poison the owners with CO.

 

You want a one-piece flue between the stove and the collar which goes up inside the collar. You can get a steel flue made with the reducer from a good chandler for about 50 - 60 quid (for a straight flue), but measure well and draw a good diagram with all dimensions. Remember that there's a gap between the flue and the 5" collar so the OD of your flue is 4 & 1/2" or 4 & 3/4".

 

Edit: It's really not worth paying for a bespoke collar for a 6" flue or using some other method to get a 6" flue through your roof. Why? Because then you'll be faced with the problem of obtaining a single length of 6" OD pipe which seems to be unobtainable unless you have it made and you'll be stuck with the slot together stuff which is generally made to a maximum length of 1.2m. (Don't ask me how I know...)

 

I don't think there's any requirement for a double-skinned flue if you are fitting it yourself.

Edited September 4, 2013 by blackrose