Woodburner air vents

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Woodburner air vents

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onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Thu Jun 04, 15 8:58 pm Post subject: Woodburner air vents

I'm soon to start building the inner cavity wall of my house, from foundation upto ground floor concrete beams, and I need to consider ventilation for the woodburner....................
I've no idea what burner I will fit so am operating a leave-all-options-open plan.
The fireplace walls are brick and block with 100mm cavity. Concrete beam and block floor with void underneath.

There is the option of direct-air stove. That is just as easy retro-fitted with a core drill - so that's that option covered. I may not go for direct-air though, so.......

My current thoughts are with vents in rear of fireplace, ducted through cavity and drawing in from (vented)underfloor void. I guess the ducts would have to be heat proof if in fireplace?
Or is it better to have the vents infront of the burner, or on other side of room ? Again drawing from under the floor (is that a good idea?(that's why I'm thinking about it now))
I'm not considering vents set in the floor as I've no idea of hearth or floor finish.
Vents high ? vents low ? optimum position ? Your thoughts / experiences.

henchard

Joined: 23 Aug 2012
Posts: 232
Location: Carmarthenshire

Posted: Thu Jun 04, 15 9:35 pm Post subject:

I'm not totally following your question. But when I did mine I could not see the point of introducing any ventialtion draughts into the house. The only way I could do this was use a room sealed wood burner venting directly to the external air; through the cavity wall. This is through a simple metal bendable flue. It is extremely simple to fit and works well.

Diagramatically it is similar to this

https://www.stovesonline.co.uk/external-air-stove.html

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Thu Jun 04, 15 9:39 pm Post subject:
Yes. External-air / direct-air is simple and easy, but not all stoves can do this - hence putting vents into room, just in-case.

henchard

Joined: 23 Aug 2012
Posts: 232
Location: Carmarthenshire

Posted: Fri Jun 05, 15 6:30 am Post subject:
For UK info see https://www.stovesonline.co.uk/stove-ventilation.html Personally I couldn't see the point of not using a room sealed stove with external ventilation as otherwise I was introducing air/heat loss in to the building.

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Fri Jun 05, 15 4:43 pm Post subject:
One of the benefits of a wood stove is that it draws fresh air into the room / house. You need this & the house needs this.

henchard

Joined: 23 Aug 2012
Posts: 232
Location: Carmarthenshire

Posted: Fri Jun 05, 15 4:49 pm Post subject:

RichardW wrote:

One of the benefits of a wood stove is that it draws fresh air into the room / house.

You need this & the house needs this.

Like a hole in the head!

Cutting a vent in a wall for a wood burner has always seemed totally stupid to me and after having lived in 3 houses (two with a vent into the living room) and now one without the vent (room sealed woodburner) I can tell you that the later is way more comfortable.

I've plenty of openings, called windows, should I want ventilation!

crofter

Joined: 11 Feb 2007
Posts: 2252

Posted: Fri Jun 05, 15 4:52 pm Post subject:
Will it be an "airtight" house?

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Fri Jun 05, 15 5:17 pm Post subject:

It will be 'airtight'. Not a theory I agree with - like RW said a bit of ventilation is good. AFAIK (this is new to me) appliance vents are sealed for the test so are not a problem.

If I draw the air from under the floor there should be less of an issue with drafts when it's windy. I can soon brick them up if I get a direct-air stove.

What I'm asking here is were is the best place to site the vents ?
Up high so colder incoming air sinks and aids circulation ?
Or opposite wall to fire ? - again to aid circulation
Or in back of fireplace so cold air is not drawn across the room ?

Ty Gwyn

Joined: 22 Sep 2010
Posts: 4633
Location: Lampeter

Posted: Fri Jun 05, 15 5:51 pm Post subject:
Out of interest,what`s the reasoning with the bison beams instead of hardcore and concrete for the ground floor?

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Fri Jun 05, 15 6:54 pm Post subject:

Ty Gwyn, on-site it is a case of speed and less labour. Beams are a bit more expensive materials wise, but less prep, less labour and no drying time or weather restrictions.
I've gone for beams for services flexibility. I can go under the floor and modify the drainage, or run cables and generally fit/route services as and when. Also one corner of slab would have needed over 600mm of hardcore (it could have been filled with concrete tho) And I reckon, up to a point, I got a bit better flood defence if there's a void under the house that I can pump (more of a bonus than a reason)

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