Rocket Mass Heater success in Saskatchewan Canada

Hi Folks; I just wanted to thank everyone on the site. I have been lurking and studying rocket stoves for some time and finally built an 8" mass heater.
It works perfect right out of the chute. No smoke, excellent draw and an aggressive sound. I've had it running for several weeks now and I like it more
each day.
We have a very old drafty house and have been heating with a home made wood stove for about 10 years. As we are getting on in age, the volume of
wood cutting was getting to much. Here in west central Saskatchewan Canada, we have some pretty aggressive winter and we usually go through about
14 cords a year.
It the first of Oct./14 now and it gets below freezing at night but warms to about 40 - 50F during the day. So far, one firing a day is plenty of heat.

Anyway, thanks to all of you for the info that I have gleaned that has allowed me to build such a great unit.

Murray Green
Saskatchewan Canada

Murray, that's great news.

What's the configuration of your RMH? I.e. bench shape, length of exhaust ducting, number of turns / elbows, and etc? Photos?

Congratulations murray: Every story like yours helps convince somebody else to take the plunge and build their own RMH. I'm guessing that you just went from 14 cord to 5-7 cord ! lets hope i'm wrong and you use 4! Remember a picture is worth a thousand words, SEND us photo's.

Thanks for the replies. Here is a little background on our stove. I wanted a large unit as we have a very old story and a half house. The spot we chose for the stove, only
allowed for a 6' bench. I decided on an 8" unit. We put 3/4" ply on the floor and covered with tin foil, then a layer of common brick. Then a leveling layer of cob, followed by
a layer of fire brick in the stove area. We have a J tube design, all out of fire brick. I rolled some 10 ga. steel for our heat riser exterior and used perlite between the brick
heat riser and the steel. (18" dia.)and capped it with some perlite cob. I then rolled some 10 ga. for the outer barrel (I didn't want to use a gas barrel) it is 24" diameter.
I built the manifold out of brick and used 8" diameter ducting, down and back in the bench and put in a water trap as the ducting goes vertical. Our bench is not finished yet
but the ducting will be totally encased in cob.
We have so much fall work to do that we won't get to finishing the stove until later but it works so well that I had to write in. I'm not sure how accurate my cheap electronic temp gauge is but it is showing about 600 degrees F on top the stove, about 400F at the bottom of the outer barrel and 200 F on the ducting as it goes vertical. I wish I had more room for more bench length as it appears to me, I am wasting some heat.
I've attached a few pictures.

Thanks,
Murray

Here is a few more.

Thank you for sharing your experience Murray. I'm a Noob, been studying these for a couple years, and am in the planning stage for installing one in our home. Seeing success stories such as yours is a real encouragement.

As a noobie, I have no real world experience to back up my supposition, but from what I've read, your exit temp SHOULD drop lower once you've completed your mass bench. If I'm not out of line, it will absorb more of the available BTU's from the gases before hitting your vertical.

May I ask, what is your estimated height of your exhausts chimney ?

I am interested because my own system (as currently planned) is very similar to your own.

Thanks,

Bob

Bob; Thanks for the note. As my house is a story and a half, I have to go around 20'. My rocket chimney is now the highest point as it is above the peak of the house.

I meant to throw in a few dimensions with my stove. The fire bricks are 2 1/2" x 4 1/2" x 9". The fuel feed tube is 12" high on the inside. My horizontal throat is 10 1/2"
on the inside and 25 1/2" outside. The heat riser is 42" (If I remember right, would have to take the top off to measure). The flow area of the stove is 50.75 sq. "
and my 8" duct has a 50.24 sq." area.
The stove fires up instantly with absolutely no smoke and begins to roar (rocket) right away. Wonderful.

Take care,
Murray

It's great to see such a success story! I have a couple of observations, one minor and one possibly major. You show the top of the heat riser as flat, which may accumulate fly ash. With strong enough draft this may stay blown clean, but it is recommended that the top surface be sloped either in or out. (I would slope it out so the ash easily falls to the bottom of the manifold for cleaning out, though if it slopes in, the flow area between the riser and barrel is greater for the same spacing.)

The major concern I have is your base configuration. You don't have any air circulation space beneath the burn tunnel. The aluminum foil does nothing to speak of when it is touching material on both sides. No matter how thick the brick/cob layer is, when there is a long burn for a cold winter day the heat will build up and might reach combustion temperatures at the bottom. What is the floor construction beneath your plywood? Is there any insulation?

Glenn; Thanks for the note. Yes, I was aware of the flat top on the heat riser and it was one of those "I should have" moments but decided it will work fine as is.
I also gave a fair bit if thought to the material under the combustion chamber. You may be correct in your observation but my assessment was that 6" of dissimilar
material would be sufficient to dissipate the heat under the combustion chamber.
There is lino and shiplap under the ply and no floor insulation as there is a basement.

Take care,
Murray

Glad to hear you have considered these items. The base might be tall and narrow enough that heat can dissipate sideways as well as down, enough to be safe for the long term. I would obviously keep a close eye on it. If you add facing to what you have, do not add any at the base - leave air circulation spaces as big as you can. If you can get to the surface of the floor from below, try testing it after a long burn to see if there is any warmth making its way through. Having that open to below should help a bit.

What kind of legislation did you need in order to not void your insurance, I'm building a RMH in sask also and I'm looking for any help as far as the leagal standpoint is concerned

Joe; I didn't bother to look into legislation as I have no insurance and don't really care what the nanny state has to say about what I do. I will say that Glenn Herbert was correct with his assessment of the base
configuration of my stove. It was in late December and very cold. The stove was fired up at 6 am and was running full bore all day. (Too much draft, heating Saskatchewan) At 2 am the following morning, I was still on
the computer and could smell wood smoke. I rushed over to the stove and to my horror, saw smoke curling up through the base bricks. Panic set in and I removed the wood in the stove with some tongs and began to let it cool down.
Thankfully, no fire but definate floor damage. I will rebuild with airflow under the stove as noted by Glenn.
  My stove is too effecient with 20' of verticle chimney and my heat loss through the air intake is severe. I will require a preheated outside air source or exhaust damper to slow down the draw. At 25 below, it will
not heat the house by burning all day. My wood stove will heat the house in a couple of hours. I love the fast lighting and clean burn of the rocket stove. We used our regular wood stove last winter and although it heats the house well, it is dirty and uses a lot of fuel. I haven't had time to rebuild yet but when I do, I plan on going to a batch system.

Take care all,
Murray

Murray Green wrote: At 25 below, it will
not heat the house by burning all day. My wood stove will heat the house in a couple of hours. I love the fast lighting and clean burn of the rocket stove. We used our regular wood stove last winter and although it heats the house well, it is dirty and uses a lot of fuel. I haven't had time to rebuild yet but when I do, I plan on going to a batch system.

Take care all,
Murray

Murray, i think your are ready for a batch box.

Cool build!  Glad you are happy with the new stove.  I agree that you are taking serious risks to your safety with no floor insulation.  Thank goodness you were home when the fire happened, or you could easily burn your house down.  Or kill yourself and your family if you were sleeping there at night.

You may not like the nanny state, but there is a reason that Underwriter's Labs test and certify wood-burning stoves.  It is to avoid killing people and burning their homes to the ground.

14 cords of wood is a staggering amount of wood to heat a single-family home in any climate.  Do you have any details on your previous wood stove?  Most wood burners using a modern UL/EPa certified woodstove in your climate report burning 3-5 cords per season: http://www.hearth.com/talk/forums/the-hearth-room-wood-stoves-and-fireplaces.6/

i agree with satamax, a batch box might be best of both worlds, so to speak.