joe fish wrote:Longtime lurker,
You can see it looks windy in the outside picture, Its always like this, not terribly windy, but a gentle flow, that often changes directions. Is this it???
I'm no expert, but have installed a few woodburners, most with unusual configurations! But - To the nitty-gritty:
My logic says that if you have smoke leaking from joints then you have: A) a good updraft, and B) back pressure stopping the smoke emerging from the top of the flue. The flue is clear so the only remaining explanation is that you have a downdraft stopping the heat/smoke exiting properly. You have plenty of updraft or there wouldn't be the pressure to push smoke through the joints. In our barn conversion I had to ensure our flue finished above the ridge to satisfy Building Control. I've not regretted it. In my past researches I have come across numerous mentions of flue finishing above ridge height. BUT - your flue looks to be by the outside wall so extending will clearly require support wires. An alternative would be to reroute the flue so that it exits the roof much closer to the ridge. I can only guess that the prevailing wind causes back-pressure. The photo of the outside appears to show smoke being pushed down and to one side although that isn't clear. The bends are unlikely to be a problem - I have a very similar setup - and the length of flue appears to be giving you a good updraft (smoke leakage at joints = pressure). These conclusions also point to the stove itself being fine.
Unimportant but relevant extras:
In our barn conversion I originally thought to put our woodburner in the corner of the lounge. We had it there initially as we worked through the build - we had one room that was very much like a student bedsit with everything squeezed into it - and the flue was a custom made steel pipe with around 8' of flexy pipe, including some 4' of almost horizontal, to allow the smoke to exit through a narrow (4") ventilation slit in the stone wall. The problem was that it was on the windward side of the barn and there was no other sensible temporary option. So, when the wind blew we would have a lot of problem getting the fire lit without turning ourselves into kippers! Once the flue was warm though, even with the weird flue, it worked fine except for occasional gusts that would push a bit of smoke back. I eventually moved the stove away from the corner and ran the insulated flue through the bedroom and out the roof around 3' from the ridge. This configuration has two 45 degree bends to accommodate a wall and to get the flue a bit closer to the ridge. (I didn't want to build a chimney or try to support a long length of flue sticking out of the roof). It works superbly and we've not had problems with back-draughts even though I have a simple cap on the flue to stop rain ingress. I looked long and hard at all sorts of different cowls but reviews generally pointed to eventual problems with anything that turned. Our barn is in a dip by a river with a big tree-covered hill behind. This causes the wind to eddy in all sorts of directions, some almost in the opposite direction! I feel the problem you are having is the same thing, with wind eddying around the building and roof to give a down-draught exactly where you don't want it.
Down by the river is our "bath-house" - an insulated "shed" with a woodburner in it that gave us a bath/sauna arrangement while we were building. It's so lovely that we still use it every couple of weeks, even though we've got "proper" indoor bath/shower rooms
The woodburner here has 2x3' uninsulated flue sections and works brilliantly. It heats a tank of water in an hour or so and we can enjoy a hot "bathroom" to raise a gentle sweat, even with snow on the ground outside. It is a relatively "Heath-Robinson" affair using an old bath rescued from a skip, water from a tank catching land-drain run-off high on the hill behind, and a second-hand insulated hot water cylinder. (Safety note - the cylinder doesn't feed a tap as that could cause explosive pressure - the outlet is a simple pipe into the bath. I have a gate-valve in place of the hot tap and that allows cold water into the bottom of the tank and that, in turn, pushes the hot out the top and down into the bath! All great fun, and very simple. This is the second iteration of bath-house after the first had a fire - mice must have nested too close to the uninsulated flue going through the roof and then we had no hot water cylinder - the woodburner back boiler just heated a bath full of water. That took three hours so gave the nesting material time to ignite. Cautionary warning - use insulated flue, or make sure that nothing unwanted can come in contact with the flue.