Two flues into one??

[T14EES T14UNK]

I think this is probably common sense but is it possible to run two stoves into one flue.

We have a stove in lounge into a 6/7 '' pipe and the bedroom upstairs has a fireplace. Is it possible to tap into the existing pipe or does another stove need another flue pipe. I am assuming not but thought I'd ask.

Cheers

[John Barleycorn]

You are right, the answer is NO.

Every fire needs a separate flue or it wont draw.

[18 stoner]

What he said^^^^

[openspaceman]

You are right, the answer is NO.

Every fire needs a separate flue or it wont draw.

 

I agree, separate flues, but it's not that they won't draw it's that one may leak into the other (probably upper) fireplace especially once the flames have died down and there is just char gently producing a mixture of carbon dioxide and carbon monoxide.

 

I once calculated the diffusion of a gas molecule in still air and it is surprisingly fast as they collide with each other every 10,000th of a mm traveled.

[Alycidon]

And its illegal under the building regs Approved Doc J, unless the stoves are in a retail

showroom. No one will sign such an installation off as safe to use and without a sign off your insurer will invalidate your cover if you ever have a fire and then you will also be prosecuted for breech of building regs, fine around 4k.

 

So in a residential property its a total NO No.

 

A

[rupert w]

I have done it,rayburn into an open fire flu,worked a treat.Every situation is obviously different though and don't know bout regs.?

[T14EES T14UNK]

Thanks for the confirmation. It is what I expected. The wife mentioned it tonight so I explained the difference between an old fashioned chimney and 6'' flue pipe and regs etc. thought I'd better just get a quick second opinion.

Cheers

[difflock]

I had the local building control officer spitting blood when I suggested it.

2 downstairs wood burning stoves back to back feeding into a 9" clay lined flue.

About 4 or 5 feet above the fire-boxes.

I did not proceed but still cannot see why it would not work.

After all if the combustion air is controlled at each stove and the 2 stoves are at the same level and the flue merge point is reasonably above the fireboxs

why not.

ps

however with one stove upstairs??

cheers

m

[finny]

Hey T14,

As the above posters, no you cannot have two appliances connected to the same flue, in some situations however it may be possible to fit two stainless steel liners into the same brick or stone flue. This will depend on the size. some bigger, older houses have flues more than a foot square..

[openspaceman]

I did not proceed but still cannot see why it would not work.

After all if the combustion air is controlled at each stove and the 2 stoves are at the same level and the flue merge point is reasonably above the fireboxs

why not.

 

Because you have created a circulation loop, whilst the vast majority of the flue gases will go upward if one stove is cooler and in a cooler part of the house than the other a thermosyphon will develop, hot gas will rise to the junction be cooled and then descend into the colder place. I imagine fluctating wind could exacerbate this.

 

I was once called out to a recent AGA installation which tested OK with smoke matches but would not start drawing in the requisite time. I had been asked to fell all the adjacent trees, on the Aga installer's suggestion. I declined the job and explained the what I thought was the reason for the problem. It was a large high ceilinged 2 storey house with a single storey annexe for the kitchen. Largely open plan, recently renovated and gas centrally heated. The chimney in the main room rose through the two storeys and exited above the high pitched ridge. The flue for the Aga used a similar brick chimney but exiting the single storey roof some 3 metres lower. The aga had been intalled without a dedicated air supply to make it room sealed and the house was no longer draughty, with new doors and double glazing.

 

So a mixture of the hot house evacuating air up the taller chimney and a thermally massive chimney to get warm enough to draw combined to stop the aga getting enough air.

 

I had worked in the grounds and delivered logs to the previous owners for about 20 years, I never heard from the new owners again. I still haven't checked if it is possible to install Agas room sealed.

 

The thing about building regs for solid fueled devices is they have to take into account the variability of fuel, modern gas or oil heaters simply won't work unless fed a fuel they are designed for but people bung all manner of rubbish in stoves and open fires and it is important to vent the combustion products well up and away from air the occupants breathe.