What size flue

[hairyone]

This weekend I was lucky enough to get two gas cylinders from Freecycle and so my project to build a log burner could start.



Managed to finish it off on Sunday and give it some test runs. Three times I tried it out and each time it eventually died back to smouldering. This occurred whatever the position of the door, even wide open.

What I did notice was that quite often the smoke would come out of the door and not a lot was going up the chimney. In retrospect I think the disposable gas cylinder for the chimney is too small (about 2.5" diameter). What is the collective opinion should I get some 4" pipe ?

I do intent to add an adjustable vent at some point but thought I could try it out by adjusting the door opening.

The next question would be where can I find some suitable pipe. Some of the fireplace companies sell flue pipe but its quite expensive and doesn't look very thick.

Thanks Aaron

 

[rtbcomp]

I would say 4 inches and it needs to be at least room height. I got a piece of brand new in box flue off Freecycle so I guess I was lucky!

 

[Unclefista]

Mine is 4 inches where it comes out of the top, then a reducer takes it out to 6 inches for the rest of the flue. It has an excellent draw

 

[Arsonista]

I think when wood burners are installed in houses they use 5'' pipe, and as RTBCOMP says, it needs to be a lot longer. From what I can gather, solid fuel burns best on a grate with an air intake under it, while wood burns best on a bed of ash with an air intake above the door. Hope this helps.

 

[wallopadonkey]

it should draw with the door open though!

the flue size looks fine for that size bottle too

drill a few holes in the back 3/4 way up 10 mm 3 or so then burn wood only on a bed of ash (ie dont clean it out)

 

[funstuie]

i made a wood burner similar to yours (I used an old fire extinguisher for chimney) and I had similar problems with the first few burns. the chimney opening on mine is 4.5" so it should be fine. It eventually settled down and smoke was coming out the chimney (flames at one point) but the fire keeps dying really quickly and the ash is not burning.

 

[rtbcomp]

Wood does burn fairly quickly, especially the less dense types. Ash doesn't burn.

 

[burnoff123]

i have got one the same with some drain pipe as the flue cut a hole for the air intakemine is about 1inch by 6 inch

 

[funstuie]

What I mean is it sits there smoldering with still big lumps left. It's goes out before burning down to ash.

Too be honest one of the neighbours looked pretty alarmed when she saw me setting fire to a gas bottle so I just did a few quick burns to get the paint off (I have since painted it with stove paint). I was a bit surprised that smoke didn't come out through the chimney at first considering the hole is big enough. It got there eventually after a few minutes and filling the garden with rancid smoke.

 

[clem dog]

Perhaps you coul try and introduce a bend to your flue as thats what creates your draw in the chimney in the house!!

 

[Bobtail4x4]

not really.

ideally you shoulnt have any bends, the flue acts as a conduit to let hot gasses out, if the flue is too cold it wont work, if there is a wind blowing across the top, often it blows back down, and you need a good air supply at the bottom to feed the flue.

 

[Jimbob]

A couple sites with LOTS of woodstove info:

http://www.hearth.com/econtent/index.php/forums/viewforum/2/

http://woodheat.org/

 

[clem dog]

not really.

ideally you shoulnt have any bends, the flue acts as a conduit to let hot gasses out, if the flue is too cold it wont work, if there is a wind blowing across the top, often it blows back down, and you need a good air supply at the bottom to feed the flue.

Ah i see then. Just remeber asking a builder why there was a bend on the chimney and that was the answer i got. Ordinary stoves and wood burners different then!!

 

[rtbcomp]

I was told you need a bend in a flue to prevent downdraughts. A lot of house chimneys have bends in them, although this may be a way for a flue from a downstairs fire to bypass the fireplace upstairs.

 

[clem dog]

Did not know that! Thought same would apply to all chimneys!!!! Thanks RT