After
stove construction was complete, it was time for a breaking-in fire to test for leaks. And this is where the
adventure began. We knew from
Permies
(my go-to place for information and questions), that first fires in these
stoves are smokey and full of surprises, so we picked a mild afternoon where
we could open windows and doors if need be.
Dan got the fire started and long story short, the room was so smokey we had
to run out onto the front porch! It wasn't bad enough that there were billows
of smoke rolling out of the open doors and windows, but bad enough to crank
up all our fans to start to exhaust it.
Since the experienced stove builders on Permies all knew about this, their
advice was to keep the fire going. This is because part of the problem is that
the stove is cold, and the chimney is cold, so there's no draft yet to pull
the smoke out of the chimney. I learned this has to do with positive and
negative pressure. As the bricks heat up negative pressure is created which
assists in getting the draft going. This is a typical problem at the beginning
of stove season and why people sometimes heat the chimney before starting the
fire.
The second reason is that the bricks and mortar aren't completely cured yet.
Not sure how that works, but we did notice that the back wall of the thermal
mass (bell), the wall that was originally
part of our woodstove alcove, didn't leak at all.
Lastly, there are often tiny spaces and cracks in the mortar that allow smoke
to leak. If the stove is properly built, these leaks stop as soon as the draft
gets going. The biggest culprit for us was around the doors, which needed more
mortar for a better seal. We also took note of a number of seams that could be
pointed with mortar to seal them.
Once we got a good draft going, all the smoke leaks disappeared, which meant
that the stove was functioning properly. We kept a low fire going for the rest
of the day and the bell gradually heated up. We were pleasantly surprised that
even a small fire heated the bell and heated the house. We would often keep
small fires in our soapstone stove on cold days to preserve some coals, but we
never got any heat out of that and the house was cold when we built up the
fire again for the evening. So, already, we were getting more out of our
wood!
The other bonus was that by the next morning, long after the fire had gone
out, the brickwork is still very warm and the house was cooler but still comfortable.
After the stove cooled, Dan set about to seal the doors and obvious cracks. I
have to admit we were both a little nervous about that second fire. However, I
heeded the advice on Permies to preheat the chimney and used one of our space heaters to warm the
chimney first. I wanted a good draft from the git-go!
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Space heater to heat the cold chimney. Heating the
chimney is only
needed when the stove is cold.
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This worked beautifully and between that and Dan's pointing the mortar, our
second stove fire was smoke free! No more smoke leaks and even the roof
chimney exhaust was clean.
What a relief.
We're still in the breaking-in stage, and still learning about masonry stove
and fire management. With a conventional wood stove, a fire must be kept going
as long as heat is wanted. With a masonry stove, only two fires per day
are typically needed. Since the stove is already warm there are no more draft
problems for the season.
I've been monitoring the temperature near the chimney flue . . .
Remember, the heat is retained in the bell so that the coolest air exits out the
chimney.
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100 F (38 C) at base of chimney
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When the stove is heated, the bricks are very warm to touch. I can put my
hand on them but they're too hot to leave my hand there.
So, except for cleaning up the bricks a bit after the mortaring, a big project
is complete. We're already getting more heat out of less wood, so it's
fulfilling what it's promised. Very happy about that!
