chimney / flues

[busdennis]

been reading a lot over the last few days about all the wood burners that have been built and one of the overwelming questions seems to be what to use as the chimney so i thought it needed a dedicated thread. please had to the list

old fire extinguisher

 

[mart]

Hi Busdennis,

Steel pipes were one of my ideas, but i found some asbestos pipes.I would advise NOT to use asbestos ones. I built a greenhouse heater/boiler and exploded the chimney as i was using coke. (i wasn`t on drugs i was using the smokeless fuel that generates an enormous amount of heat). The blast blew a hole in either side of the chimney. It actually "draws" really well with these holes in the side (a bit like them old bunsen burners that we used to use at school).

If you only need a small chimney to go out of a garage/workshop, you could use some old cast drainpipe. If doing that now i would drill some "draw holes" in the side near the base-(see pic of the blast holes in the asbestos pipe)

 

[peterd51]

Hi,

for a stand-alone patio heater, what would be the best height for a chimney?

Two feet, or much higher, say, six feet?

Regards
Peter

 

[Justme]

Those holes will give you a jet engine flue fire once enough combustables are deposited on the inside of the flue.

Once a flue leaves the stove it should be air tight.

 

[Arsonista]

Once a flue leaves the stove it should be air tight.

I agree. Chimney needs to be about 5'' dia too.

 

[busdennis]

just trying to get the thread back on track a bit
looking for a list of useful items to make a flue out of

thanks

 

[brightspark]

just trying to get the thread back on track a bit
looking for a list of useful items to make a flue out of

thanks

dont u know anyone renewing a cast iron soilpipe or even one from the scrappy s

 

[pidgeon chit welder]

been reading a lot over the last few days about all the wood burners that have been built and one of the overwelming questions seems to be what to use as the chimney so i thought it needed a dedicated thread. please had to the list

old fire extinguisher

We had a wood burning sauna ...happy days

Wood burners can burn far hotter than you think especially if you use smashed up , cut up chipboard from a kitchen fitter friend like I did. We got a fair dark cherry glow all round the burner and a bit brighter in the lower chimney

The safest thing ( we ended up doing this ) is to buy the available insulated stainless flue sections & heat shields , fit them right from the burner to the last item ..don't forget to add a rain ingress prevention device and supports as recommended by the manufacturer.

If you are seeking to use the chimney as a heater surface as well, some high grade steel pipe , cut and welded at angles to take any bends and a long straight bit that takes the exhaust at least 1 mtr above any combustibles.


Alllow for some form of expansion though , for our wood burning Sauna didnt have much , the serpentine pipe flue /chimney kept cracking at just above the red hot heat affected zone some 800 mm out the back of the stove.( haze ).

The stones were granite right from the start ( others crack and explode from heat & the cold water being chucked on them )

Have fun designing the heat shield through any walls especially wooden ones

 

[pidgeon chit welder]

Hi Busdennis,

Steel pipes were one of my ideas, but i found some asbestos pipes.I would advise NOT to use asbestos ones. I built a greenhouse heater/boiler and exploded the chimney as i was using coke. (i wasn`t on drugs i was using the smokeless fuel that generates an enormous amount of heat). The blast blew a hole in either side of the chimney. It actually "draws" really well with these holes in the side (a bit like them old bunsen burners that we used to use at school).

If you only need a small chimney to go out of a garage/workshop, you could use some old cast drainpipe. If doing that now i would drill some "draw holes" in the side near the base-(see pic of the blast holes in the asbestos pipe)

It could be that the reason the asbestos tube exploded is that asbestos does just that when taken past a certain temp, it is a big problem for fire fighters

Asbestos exploding sounds like a shot gun being discharged and you dont want to be with in 3 mtrs if at all possible.

 

[mart]

Your not wrong. I was in bed at the time, it was about 1am-it sounded like world war 3.Had to rush down and throw buckets of water on the cokes to out them-you live & learn.

 

[pidgeon chit welder]

Been thinking more about these flues for wood burners ... make a removable trap below the point where the cross pipe comes from the fire and joins the upright of the true chimney .

That way you can have tars run down it and a wee bit of soot fall . Drill a small witness 8 mm or so hole low down in the trap so that it not only gives a bit of up draught it will show if the trap and chimney is in need of cleaning .

We have had wood burners and there is a good chance that like us you get a wood sap /resin residues build up in the fire box , flue & chimney there is a product called Scoot and one called Imp that once a month you bung a dessert spoonful on a lit fire it helps carbonise & crumb the residues which then burn off. Most coal merchants sell it as a bye sale

Solid fuel stoves are not quite so demanding but the scoot etc does help if done a couple of days before giving the chimney its annual brushing out

 

[bullet]

a mate of mine has just installed an open grate fire, looks like a cast iron create, he's put a hood over the top to his flue, now when its lit and going smoke is coming out in to the room, does he need an air intake in the flu to draw the smoke up wards? any help would be greatfull thanks
bullet

 

[Bobtail4x4]

He probably needs a bigger/higher flue.
the regs ask for 15% of the open area.

 

[pidgeon chit welder]

a mate of mine has just installed an open grate fire, looks like a cast iron create, he's put a hood over the top to his flue, now when its lit and going smoke is coming out in to the room, does he need an air intake in the flu to draw the smoke up wards? any help would be greatfull thanks
bullet

Is there an unrestricted fresh air flow into the room for the fire to draw and exhaust .

Was the chimney swept before hand to make sure it is free of fallen bricks . old nests/bees nests etc.?

 

[pedrobedro]

a mate of mine has just installed an open grate fire, looks like a cast iron create, he's put a hood over the top to his flue, now when its lit and going smoke is coming out in to the room, does he need an air intake in the flu to draw the smoke up wards? any help would be greatfull thanks
bullet

He needs more air going into the room while the fire is getting established, just leave the door or window open to let the heat from the fire rise and take the smoke with it. We used to hold a sheet of newspaper across the front of the hearth to draw it up faster.

 

[pidgeon chit welder]

It could be that the fire place has been removed /altered at sometime and that parts of the fire back have been removed etc.

In 1981 the home I moved into was a former council house, it had a 1950's cream enamelled fire place with slightly darker colours on the mantle piece tiles & hearth but no fire basket or grate front.

It was a bonus for it had a back boiler . Ha ha thought I, room heat, hot water most of the year and 2 thermo syphom rads.
Yep I was going to love this place with the old fire. I took out the 1960's gas fire and plugged the pipe correctly .

Then I swept the chimney and got a full dustbin of soot on the first sweeping .. the second sweeping gave up another 1/3 . Thinking I was all set for a coal fire I got 1/2 tonne of smokless stuff delivered from the coal merchants that were only 200 yards away .


I went to town , sourced a basket and grate front then lit the fire, went out to the garden to start shovelling the coal into a cleared out shed ..Then saw the lounge windows were the colour of big yellow London pea super smog.
A while later saw all the windows open and me scraping out the fire . God everything stank for weeks despite washing everything down and shampooing the whole place .

It transpires that there should have been a carefully angled and curved cast iron throat plate bolted up just inside the chimney on a cast iron frame almost at mantle piece level . It was missing entirely .. Could I get a new one could I chuff.

I tried to make a throat plate up at work but it just didnt have the correct curve to make the throat draw the fire.

I'm wondering if not only does our friend live in a sealed double glazed home with little or no air flow through it, should there be a supplimetary throat plate in the chimney to make it draw/work?