Running flue through upstairs bedroom

Hi

I have a fairly powerful woodburning stove with a 125mm flue.

I was hoping to run the flue vertically through the ceiling and floor above and in the bedroom above build a block chimney with 45 degree bend inside to vent through the wall.

I would have fireboard where the flue passes through the ceiling and after that the flue would be surrounded by block/cement.

The idea is to use the heat in the flue to warm the upstairs room before the chimney exits the house.

Any suggestions/comments?

Dave Quinn : Do a Google search for the term stove pipe thimble ( West of our mississippi they generally call it a stove pipe jack ) The next best thing would be a 200 mm hole

in the ceiling / floor and a wire cage around that ! I don't understand the 45 degree comment, I hope you are going to have a professional to put in what is usually called a 1/2
chimney, that is any masonry chimney that starts above the 1st floor, they are common in my part of the company, but nowadays have usualy been replaced with insulated stove
pipe to penetrate the outside wall/roof of the house ! Good Luck !

For the Good of the Craft ! Think like fire, Flow like a gas, Don't be the Marshmallow ! As always, all comments and questions are solicited and are Welcome ! Big AL !

Thanks for that.

It wasn't meant to be a full height chimney. Black enamel stove pipe up to ceiling through floor (I was going to 'make my own cage', but could I use a thimble?) Once I've gone through the floor I was intending to basically run the flue (insulated stove pipe) at 45 degrees through the room them out through the exterior wall and then up the outside of the house.

I was intending to Encase it in cement Block to provide 'warm stepped shelving'.

Not quite sure, but the thimble's seem to be for going through outside walls. Can you use them through a floor?

Quite a few comments about needing 3' clearance! I was thinking more that 1' - 1'6" 300mm - 450mm should be enough?

Dave Quinn : We have to talk worst cases here, The emergency that pulls you out of the house, with no thought to to immediate or the delayed consequences of your actions !

Just plain wood, ceiling/floor members, joists, rafters and wall studs Will In the presence of high temperatures, slowly out gas, or pyrolyse, This occurs everywhere, but mostly
in confined areas with little or no air exchange. Eventually The jousts, studs, rafters, lose up to 50% of their mass, becoming a grey mass as light as charcoal, and unable to
support its own weight ! This type of out-gasing never sets off a smoke detector, (think burnt popcorn)

Often these areas are found during 'home improvements' after decades of slowly pyrolyse-ing away!

Sometimes, The homeowner is 'called away' and depends on the system to take care of itself one more time! This is the perfect scenario, The one that makes the news, the
owners/renters were not home!

This is the reason for the setbacks that you see recommended, that, and The Idea that you do not want to leave a booby-trap for the next homeowner !

Thimbles are fine for floors and walls, and should state so right on them ! I would build a cage around all of the non-insulated stove pipe, ether a heavy wire mesh or some arrange
-ment of cinderblocks, being more air spaces than block, to soak up the radiated heat, they will always re-radiate at a lower temperature out into the room.

I would actually go to the step of glueing aluminum foil shinny side up directly onto the floor, then brick pavers as spacers then your 'Cement Block'. Again it is the dead air spaces
that you are trying not to create that bite the Homebuilder on the But ! Hope this helps !

For the Craft ! Think like fire, Flow like gas! Don't be the Marshmallow ! As always comments / questions are solicited and welcome Big AL !

Some more details of what I was planning to do.

The main joists for the upstairs ceiling have an approx. 62 cm gap.

I was planning to remove all floor boards for a square about 70cm in size the joists would be slightly smaller.

The galvanisehttps://permies.com/t/25834/cascadia/Farmstead-Meatsmith-Kickstarter#204134d black enamelled stove pipe 125mm would go up to ceiling level and be connected to an double lined flue.

I was intending in using fireboard and steel supports to keep flue in place and then use a steel mesh to form a concrete base for the block chimney. I was intending to use concrete gate posts to build the flue 'container/shelf'.

I was then planning to angle the flue at 45 degrees and go the exterior wall brick and concrete before another 45 deg turn to run up the wall.

I thought this would give enough elevation for good chimney draw and still allow some retained heat in the bedroom. Obviously not as much as running a stove pipe through the concrete, but some. What I can't understand is how it's ok to run a rocket stove through thermal mass, but not an ordinary stove pipe?

Dave Quinn : In no special order - Yes to your floor opening ! A safety cage just to keep small hands away will work whether it is a steel mesh or stacked bricks, black stove pipe
will come up to temperature making a good draft, better than a masonry block chimney!

We should probably discuss your location and climate !

After the black pipe is up to temperature it will radiate heat out into the room while the Masonry chimney is still soaking up heat, later when you have your downstairs toasty
warm, the stove pipe will cool of by radiating about half of the heat left in it ( not Much ) equally up the chimney and into the room. With the masonry chimney doing the job
that it was created to do most of the heat will be sucked out of the masonry and out the chimney !

It will be cheaper for you to pass up through you ceiling/floor, and into a second floor bedroom vertically with stove pipe, turn at Right angles (90degrees) and then across the
room to your outside wall where you ? are going to use another elbow to pass through to the outside where you will then need a third elbow to turn your stove pipe to vertical ?
or are you using your 1st elbow to go from vertical to horizontal, and then just one (1) more elbow to turn your stove pipe back to vertical after you have gone through your
exterior brick wall !

In any case you will get more radiated heat off of your stove pipe than out through the mass of a 'Cement Block' Chimney! Ideally you can surround the stove pipe with stacked
masonry that is as much air space as blocks to allow for air flow ! Some use of fire board with a dead air space on the side opposite to the chimney would be a major safety item

What We call the Heat Riser inside of A Rocket Mass Heater, is a very powerful interior vertical chimney ! To get the same effect with a conventional chimney on the exterior of
the house, it would have to be 60+ feet, 18+ meters ? ! Your final stretch of vertical pipe outside the house needs to be at least as tall as the highest peak on your House !

This push-me, pull-you effect is what allows the hot exhaust gases to flow horizontally for so long a distance Through your thermal mass !

I hope I have made this a little clearer to both of us ! - Don't be the Marshmallow ! As always, comments,questions are solicited and are Welcome BIG AL !

Brittany - Northern France. Atlantic temperate, but 30km from the coasy and reasonably high , it can get pretty cold in Winter.

I realise the stove pipe would more effectively heat the bedroom, but was concerned that his would be a safety hazard as it would get 'too' hot.

I have also been told that 90 deg bends and horizontal runs are not permitted in stove pipes?

Also been advised that I need double walled to go through ceiling?

Thought I was starting to understand

Dave Quinn : Dave, you probably are just dealing with different interpretations of local codes, we do want to be safe, I was counting the thimble as your double wall section,
I will always work to meet or exceed codes! Over 30 years of selling and installing heating systems on this side of the Atlantic, and I would be afraid that If i varied from
common practices around here some one would tell me that I didn't know how to do my job !

I think that you are dealing with a bit off Gaelic Canny-ness (being miserly with a Frank) that has found its way into local code. If you allow for 2 meters of Vertical chimney
for every 1 meter of horizontal chimney, and end your stove pipe about a meter above the tallest peak on your house you should have no problem with a good "draft '' in
your chimney !

You are within the traditional belt of Bocage that almost cost the Allies the price of a successful invasion, and a belt of local trees may raise the requirement for chimney
height at your location, time will tell for you but you should get a good idea from your neighbors houses !

A thought, You may have a requirement for a clean out with every 90 degree connection, and this is a way to avoid this requirement.

If you choke down the air supply to your conventional wood stove at night to hold a fire overnight, you would have a dirty fire and soot and creosote will settle out, mostly
in the horizontal run, though water vapor condensing in your exterior chimney catching the soot and creosote will be slightly more common if your draft carries it past the
horizontal sections !

So, go with local requirements, longer horizontal runs will pump more heat into your upstairs bedroom, and actually slow down your draft slightly.

Again as long as you have a reflective barrier above your stove pipe, with a channel for air circulation on the other side away from the stove pipe you will re-radiate the
heat ( 85-ish %) away from the walls and ceiling.

Most of your problems would be none existent with a good rocket stovemass Heater, but that is a story for another day !

For the Craft ! Think like Fire, Flo like gas, Don't be the Marshmallow ! As always your Comments and questions are solicited and welcome BIG AL !