Chimney convection

[ChrisT]

I know of someone who did it years ago, but has anyone else heard of running a pipe alongside the flue with an exterior vent low down, then runs up and into the room above you obviously have to be able to shut it off in the upstairs.

 

The idea being that it convects warm air up into the room above? It isn't always practical and could be a lot of work, but would use some of the wasted heat from the chimney.

[Alycidon]

So a flexible lined flue within a chimney?.

 

Some stove manufactureres (Stovax?) do offer stoves with an air vent to above facility, the pipes are not routed via the chimney.

 

Heat gains doing what you are thinking will be minimal, not sure if its legal or not, you will also get smells into the room from the old chimney. I would suggest that its not a good idea.

 

A

[Nick Watkins]

It's common in France

 

KIT DE DISTRIBUTION D'AIR CHAUD / Magasin de Bricolage Brico Dépôt de Perigueux - trelissac

[Nick Watkins]

 

Heat gains doing what you are thinking will be minimal, not sure if its legal or not, you will also get smells into the room from the old chimney. I would suggest that its not a good idea.

 

A

 

Actually heat in the upstairs room is pretty significant and with no smells. I have no idea about the legality of it in the UK though. If I was ever re-doing major work on my house I would put this in without a second thought.

[openspaceman]

I know of someone who did it years ago, but has anyone else heard of running a pipe alongside the flue with an exterior vent low down, then runs up and into the room above you obviously have to be able to shut it off in the upstairs.

 

The idea being that it convects warm air up into the room above? It isn't always practical and could be a lot of work, but would use some of the wasted heat from the chimney.

 

I cannot see there being room for a flue liner and another pipe inside the chimney and if you mean just running a pipe inside a chimney so the exhaust gases surround the pipe I also don't think it a good idea:

 

1) You are breaching the flue to exit into the upper room and the seal may fail

 

2) You are cooling the flue gases and if the temperature gets below the dew point of any vapours they will condense on the pipe and chimney walls. As a consequence of having a cold flue the buoyancy of the exhaust will be lower and hence less draught or worse a downdraught caused by an internal circulation.

 

3 How will you clean the chimney?

 

You have to consider what the function of the chimney is, it is to evacuate combustion products, to do this without a fan requires a draught from the higher buoyancy of flue gases than the household air. The flue temperature needs to be above 100C at the chimney exit. So really if there is still excess heat/high temperature to be recovered at the stove flue then it shows the heat exchange of the stove isn't good enough.

 

If I've got the wrong end of the stick and you just want to use a stand alone warm air distribution system then I've no problems with that. Our upstairs is entirely heated by warm air from the Jotul rising up the staircase and percolating into the bathroom and bedrooms

[ChrisT]

I did think of the idea of surrounding the flue.

But our chimney would take 2 6" flue pipes and then vermiculite insulation, but it is an old house with a brick lined chinmey, like I said I know of someone who has done it but not how exactly how he did.

He apparently had to close it off because the bedroom got to hot.

 

I did have the idea of somehow surrounding the flue with copper piping to run a central heating system but this would definitely drastically reduce the flue temperature.

[broonie]

why not use a heat recovery unit?

[ChrisT]

What is a heat recovery unit? I am new to this an interested in learning something new.

[twistedhicap]

try looking on the green building forum there is alot of usefull stuff there that you will like im sure !