Ive been trying to get a second hand valve but with no luck. Not many three inch ones about. Not that It would need a full 3 inch 90% of the time.Made one out of a small gas bottle a couple of years ago for my caravan. It works well I used an old exhaust pipe for the chimney.
Just rely on drafts for air intake but like your idea of a pipe to the outside i might add this to mine could put a gate valve in to control the draft.
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Ive been trying to get a second hand valve but with no luck. Not many three inch ones about. Not that It would need a full 3 inch 90% of the time.
The issue was with the air intakes coming from the front of the caravan. Ok when dry but bundling along in the rain will undoubtedly flood the pipes and let water into the stove. I have settled for a slide damper on the main intake and nothing on the secondary one. I will just have to create a couple of transit bungs that will need to be fitted on the outside when towing.
Could make up something like this to control the air intake?.....
See if you can knock up a dragon cowl. They rotate in the wind and help the draw. There are a few diy vids on utube.My little wood burner is plenty to heat the small caravan even in winter I can fill it and close the burner door so not too much draft and it will go all night with just a gentle flame. I found though when no wind and raining or foggy sometimes it would not burn too well so I made a chimney extension which just slides on and i take it off when towing. I am going to weld a bit of 1" steel pipe with just a normal brass gate valve in it and a hole out the side, probably just leave it flush and put something like a fridge vent over it on the outside. I have plans to one day maybe mount it on a sankey chassis. Be interested to see your trailer when done.
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Just your own?!!Oh and I refuse to drink my own urine.
I struggle with the welders I have. One is great at very thin stuff and the other can blow holes in half inch plate. I always find it a fight.I think that I like the handle and the attached slidey trappy air intake even more than the justsatisfyinglytightenough lever. And if you think those welds are crap I could teach you a thing or two.
Not always easy when it has to be gas tight but I see what your saying.There you are - I weld thin stuff together by clamping them tightly and simply burning a hole through both. The edge of the hole is often a textbook weld and the big advantages are the weight saving and ventilation. Sounds like you're up to speed with the heavy stuff though.
Id live to have a go with a proper mig. Something adjustable that will tackle everything.