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. |
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 . . .
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| 100 F (38 C) at base of chimney |
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.
20 comments:
Very impressive. What is that single decorative square tile on the front to the right and between doors?
Michelle, what Dan was doing the brickwork, he in inadvertently mortared two bricks one on top of the other instead with seams matching rather than staggered. So visually, it made a square. The decorative tile was something I picked up on clearance years ago and fit in that square perfectly. So he mortared it there for me, sort of as a signature touch. He's not impressed but I like it!
Nice! We have not had to use our woodstove since we installed a propane heater in our living room. I literally heats the entire lower part of the house.
Kristina, that's the kind of heat you want!
This sounds great. I wondered if cold chimney was part of the smoking issue. I grew up with open fires in the UK, and you always held a burning taper up into the chimney before you lit the fire, for that reason. Your masonry stove is great, many congratulations on your success. This will be so good all winter.
I guess I'm not surprised about the first fire but it is interesting to know that it retains enough heat that the preheating only needs to be done that first time. My next question will be how long can you go without a fire before you have to preheat it again which would dictate your schedule somewhat. Since we are usually once a week fire people during the winter, this will probably not be something practical for us. It sounds perfect for your lifestyle though!
So glad the field test went well Leigh! I would likely be a complete wreck waiting and watching.
Heating of the chimney is an interesting side note. I am looking forward to how this performs over time and changes your routines.
Ed, that's a good question. It will be something we'll just have to learn by experimentation. I'd also like to find some alternative ways to preheat the chimney. Someone on Permies uses a blow torch! The space heater is fine, but it would be nice if we could do it with candles or something non-electric as a backup.
TB, if we hadn't done so much reading about it and knew what to expect, we probably would have freaked out! One thing it will help with is the quantity and size of the firewood we need. Dan has an eye to the future and would like to not have to cut down trees. This particular stove uses smaller and less wood for one big fire that heats the stove for the rest of the day.
Liz, thanks! That would be an excellent way to preheat the chimney. Some people build a very small fire at the back of the stove to do that. I'm guessing we'll be doing some experimenting.
That fire in there looks pretty! I envy you Leigh and Dan! Burning less wood is a plus. Can you use lumber scraps and smaller branches in it? What about coal?
Congratulations to you and Dan - this project is one you'll feel proud of forever!
Kevin, it is designed to use small pieces of wood rather than logs and big chunks. So scraps and branches would be perfect. That's part of the appeal for us as we get older. We get plenty of windfall branches, but cutting down trees for firewood is a real job of work.
Coal is a different animal altogether, so I have no idea about using it for fuel. Possibly some of the old masonry stoves in Europe burned coal, back before it as a big no-no to do so.
Quinn, I'm thrilled with it already!
Although not perfect and not for the impatient, but on the coldest days I find just opening up the fireplace door and walking away for 10 or 15 minutes is the best way to preheat our fireplace. It generally allows most of the cold air in the chimney time to sink down and be replaced by the warmer house air rising up. However, my fireplace flue has a direct shot upwards and yours doesn't so I don't know how effective that would be in your situation.
Good Morning! Nice build.
Did I miss a link to the plans for this awesome looking Bell Style Rocket Mass Heater?
Would fit better than the barrel bench style in my basement.
Using it keeps it warm enough that the first few fires of the season have the smoky issues.
Oddly a dab of wood smoke was in the tropics the "house medicine" that kept termites and mice away. It was noticed after smoky cooking stoves were replaced by propane and such that termite control required yearly spraying lest you lose your home. Rodents likewise story.
Now, for the first food cooked in the oven!!!!
(Re-posting this because the first one had a long blank gap in it. Probably the cat wiggling around in my lap :)
Ed, you're probably correct that your solution wouldn't be effective with our setup. Yesterday I watched Paul Wheaton's "Free Heat" movie and learned about "cold plugs," where the cold chimney basically blocks the heat from escaping (until it builds up pressure). Some folks put a port of sorts at the base of their chimney to preheat it to prime it. Not sure if we'll go that far, but it's an idea. Simplest is best, like your simple but effective solution of opening the fireplace door.
Michael, thanks! No link to plans. We went through a lot of them and brainstormed a lot before deciding on the simplest design we could, just a big box. There are quite a few examples at permies.com and batchrocket.eu. Hopefully, I documented the build pretty well with photos in my masonry heater posts. The core is a DSR2 (double shoebox).
We didn't have room for a bench so went with the bell. We were interested in the barrel, but eventually nixed it due to cost. I have to say that the cast iron doors (from Firespeaking.com) do a good job of transferring some heat to the room quickly, which is nice. Right now we're firing it up twice a day and the bell stays nice and warm in between, so we're comfortable.
Interesting about smoke, termites, and rodents. It would likely take plenty to deter them. :)
Rosalea, that's the next step. :)
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