Today we lit up our wood stove, but the smoke was exiting from inside instead of out of the flue. We were puzzled by this, but learned that it was because there was a column of cold air inside the flue preventing the smoke from rising. First time this has happened. It eventually did draft outside, once the flue warmed up. Starting a fire from a cold stove will be tricky, anyone got tips?
@rek Next time we'll try adding an extra length of pipe outside to lift the smoke head from the deck. That may help with draft, although we never had draft problems before...
A black chimney would become warmer than a metallic one, but only if there is sun enough to heat it, of course.
Also some insulating material around the pipe would help.
@GustavinoBevilacqua yea it's real cloudy today, was also windy when we started it up, adding to the chill.
@rek I always struggled with this with wood stoves. My father in law always starts with a little paper fire that burns hot and fast to hep build the draw. Some recommend holding the fire almost in the flue.
@rek nobody likes a Smokey room :( I can usually get it going when its just us but when they are there I fail every time, like some sort of performance anxiety.
@peregrine lolol same. Things I master in private I manage to fuk up when ppl are around.
Yea at least it was windy so opening the front hatch and door aft helped vacate the smoke pretty quick. Good way to test our detectors too, they both rang and that is a good thing.
@peregrine @rek In fact, this is the only way I know to start a fire in a wood stove, and is how my father taught me when I was younger! You wad the newspaper up extra tight, too, to get as hot and as long a burn from it as you can. He'd usually add "lighter'd", or resinous pinewood sticks that had dried until the resin was rock hard, to help the wood catch. I always assumed the newspaper was just a simple fire tinder until I learned more about pre-warming a stove.
@rek We use wood heat as well. If the flue is cold, I'll light a piece of newspaper in the stove first, to get the updraft started. Something that will burn fast and hot, with minimal particulate.
@rek can you install a little hanging tray inside the stove to keep the priming fire up against the flue?
Then once the flue is warm you can light the logs
@dualhammers I put a candle in it this morning and left it there awhile and it worked quite well :>. Stove is small enough that the candle works well.
Not rly enough room for much in there, firebox is only 9x9
@rek if you can burn a little primer fire of something that burns quite hot first to flush out the chimney that can help. Like some not too tightly screwed up newspaper. Then light your proper fire after that. An insulated flue can also help :)
@Nonverbalpoetry Pre-warmed the flue and made another fire this morning, no issues :>.
Yea, our flue isn't insulated, we couldn't find any insulated 4" ss piping in our area at the time of installation.
@rek ours isn't insulated either, and actually, with the heat it kicks out, I'm pretty sure an insulated flue would not be as good at warming our boat. Glad the pre warming worked :)
@rek I don't know the details of your setup, but for most stoves you need to prime the flue when starting cold. A small hot fire or some air pressure forcing movement upwards for a bit to get the process going in the right direction (the latter is what gas furnaces are doing when they start the fan before igniting, if you want a model to consider)
@rek Chimney backdraft. Depending on the cause, a longer chimney may help, and starting the fire hot. Wood shavings from a plane work better than paper.
If the cause is wind pressure, there are storm flue cowls. Refleks even makes a "H" shaped one that is designed to work at sea in a storm and lets gases escape but keeps waves out.
Another cause might be that wind blowing down a hatch, vent or a running extractor fan is creating a (small) vacuum in your cabin.
@rek Yeah. Newspaper close to the pipe always. Also, we went from a russian mass heater to a rocket stove and the rocket almost never has this problem. It starts fast and hot easier.
@rek Never needed this, so no personal experience, but apparently letting a single candle burn inside the stove for a while is enough to get some updraft going.
After that, I'm a fan of the Swiss method where you light the fire from above, and let it burn down through the material, giving a nice slow start with less smoke.
(The idea being that the updraft isn't very strong yet in the beginning, and building a big fire all at once produces more hot gas than the flue can handle right then.)
@Coffee I tried the candle method this morning and it kinda works :P! The lower section of the flue was a tad warm. Fire started without an issues :>
@rek I used to burn a newspaper for a "Lockfeuer" to create the "Kamineffekt". (Sorry I don't know the English words for this). If you have a lever on your chimney pipe, make sure it is all the way open. If this is not going well (bad weather, cold inside, warm outside), you can use this wooden fire starters (see picture) in addition.
@rek do you have to carry a substantial amount of wood onboard to keep things warm when you sail around? or are you currently close enough to shore where you can get away with smaller bundles that you restock more often?
@stevenleeg We're close enough to shore to re-supply. But it's not too cold right now, so we're not going through our stock terribly fast.
@rek candles (keep the flue warm on an ongoing basis), or even a suction fan at the top end which you remove when things get heated up a little. It doesn’t take much to get that column of air heated and flowing but two things are against you guys in particular - the insulation issue, and the length of your flue. A longer flue will naturally draft better in a broader range of conditions (colder indoors, for example). Active draft with a removable electric fan is probably the easiest way to go.
@rek and to be clear, I’m not implying that you should lengthen the flue. I suspect it’s not possible to do so sufficiently on your boat, so that’s why I’m saying go active, either actively heating the flue or actively suctioning the air. Even I have this short-chimney issue in my home, and I have a 12ft chimney. You need something like 15+ft insulated pipe to make a natural draft easy.
@d Yea we had a length of pipe i thought we could use as a flue extension when at anchor, but the damned thing doesn't fit well on the deck iron mouth. But anyway, priming the flue has worked for us since I posted that call for tips :).
@rek It is a problem of short chimney and/or the way your stove is connected to it (horizontal pipes do this). You can overcome it by warming the chimney base, so that the air starts to go up the chimney (I allways have to make small fire in the chimney, before I light the stove at my cottage). If your chimney construction doesn't allow for warming it from inside, maybe you can try to warm the pipe from outside...
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