~$900 Small Masonry Heater Proposal

[byQ]

The goal: Build a small contraflow masonry heater for $900. How small is small? 3' wide, 2' deep, and 6'-7' tall. This is a good size for a small or well insulated house. Or a house on the coast or in the South. Also a good choice for a cabin, or for heating a large room.

Performance goal: Will be the the highest of any wood burning appliance - even higher than a pellet stove (down with the old King). This heater will utilize an Eco-Firebox. This is a firebox designed to let air hit the fire from all sides thus boosting burning efficiency.

Cost Savings-How?: The unit must be owner built (it isn't that hard). The unit needs to utilize outer materials that are low cost or free (this part is easy). The small masonry heater isn't allowed to have a bake oven (it is too small anyways). It can have a bench, though.

And you must use a small door without glass - ugly? Maybe. Efficient? Yes. Cost effective? Yes. How will I know when the fire is out? You'll have to open the door and look.

Like this size or a little bigger (without the bake oven),


(to be continued)

 

[BenTN]

Following...

 

[peakbagger]

If you haven't seen Dick Hills masonry stove design you may want to check it out.

 

[Babaganoosh]

How does your insurance company feel about a homemade heater that involves open flames? Probably not good.

However I love your idea and enthusiasm .


900 dollars? My stainless steel chimney cost more than that . I don't want to be a Debbie downer btw . I'd love to see you do this.

 

[electrathon]

How does your insurance company feel about a homemade heater that involves open flames? Probably not good.
.

Isn't this the definition of a masonry fireplace? A lot of houses have those.

 

[Babaganoosh]

Isn't this the definition of a masonry fireplace? A lot of houses have those.

The key word was homemade.

 

[electrathon]

The key word was homemade.

I guess I don't understand. All masonry is homemade. Porches, foundations, fireplaces, etc. Way to big, heavy and unstable to factory build a masonry fireplace. There are metal fireplaces that are factory built, but masonry is built on site, by hand. Rocks and bricks are cut, mortared together and wala!, a fireplace.

 

[begreen]

Is this a different project than your current masonry build?

https://www.hearth.com/talk/threads/mh-puzzling-together.155464

 

[Sprinter]

That puzzles me too. Seems like byQ has just about finished the heater. Now all he needs is a house to go around it... (Which might be the easy part LOL)

Regardless, I'm wondering why a glass door would be inefficient? It seems like just another radiant heat surface which is the whole idea as I understand it.

 

[byQ]

Is this a different project than your current masonry build?

https://www.hearth.com/talk/threads/mh-puzzling-together.155464

I was thinking about assembling a kit and finding a victim, I mean person, to sell this first attempt to at cost. I would probably make some detailed instructions to go with it.

 

[byQ]

That puzzles me too. Seems like byQ has just about finished the heater. Now all he needs is a house to go around it... (Which might be the easy part LOL)

Regardless, I'm wondering why a glass door would be inefficient? It seems like just another radiant heat surface which is the whole idea as I understand it.

A glass door isn't inefficient. A glass door is expensive - a basic glass door is $450. A fancy glass door, a $1000. A door for a bake oven, $400. And the refractory concrete slabs for an oven probably $100 more. A glass-less door should be less than a $100. If it is possible to get an inexpensive glass door - I'm for it.

I'm interested in the VW bug design not the Mercedes Benz design. A heater that works really well, performs excellently, and looks fine. And is cost effective, also. A masonry heater option for the average person.

 

[hierony]

Alex Chernov's article about a cheap, no-frills masonry heat is probably byQ's inspiration.

I'd say $900 total is a wee bit ambitious, but mainly due to auxiliary costs. I was trying to go reasonably cheap on my build but I hit ~$1500 (materials, tools, foundation, but not venting). The thing that cost the most was the stove/chimney pipe (~$500), not too surprisingly.



So my no-frills 27x27" 5.5 ft tall eco-box masonry heater cost breakdown:
$200 design fee
$105 firebox door (no glass, large ash box cleanout door repurposed)
$85 two ports (air inlet port & cleanout port)
$252 firebrick core (200 at $1.26 each, new)
$120 refractory mortar
$88 castable refractory
$111 vermiculite firebox baffle (4x times needed)
$28 1/2" ceramic blanket
$52 1/4" ceramic blanket
$20 perlite
$80 facing brick (170 bricks at 28¢ each + 70 brick at 39¢)
$30 thinset mortar
---------------
$1171 materials total

$530 for chimney (2 ft stovepipe & damper, stovepipe adapter, 7 ft class A, cap+spark arrestor, support kit, silicone boot)

This doesn't include things like a brick saw/table saw, ceramic saw blade, N95 dust mask, margin trowel, mortar mixing paddle, protective gloves, levels, string lines, plastering, or the _foundation_.

I could have saved money here & there: tile for cleanout access instead of port (-$43), smaller piece of vermiculite (if findable; -$70), doubled up the 1/4" ceramic blanket instead of purchasing 1/2" (-$30), not miscalculated the needed facing brick (-$12), not overused the refractory mortar (-$60). I *could* have made my own design, but I wanted technical support & an experienced hand to come up with something reasonable. Someone suggested re-purposing a door from a used/abandoned wood stove--I don't know the feasibility but maybe -$100.

I don't like the lack of a view into the firebox--learning to light the thing is a royal pain. I may mill a 1-2" hole in the firebox door & put in a piece of tempered glass. Also, the door closes with a fine pitch bolt requiring a screw driver to open/close--I need to find a reasonable handle attachment for the door closure as well.

 

[byQ]

If you haven't seen Dick Hills masonry stove design you may want to check it out.

Thanks, I've never seen this build before. Here is a write up.

http://www.hotandcold.tv/masonry_stove.html

 

[byQ]

hierony, your masonry heater is looking good. You must be pretty happy with how it turned out. I bought 3 clean-out doors (12" x 12").


And I'm faced with the same problem. I went to Lowe's and found a little metal 'T' handle and was going to have that welded onto the end of the screw.

 

[hierony]

The threads look to be M6x1.0, so you could conceivably get a 1/4" steel rod, bend a short 90 in it, thread one end & put a typical stove spring handle on the other. You'd need to weld or solder a shoulder (small washer?) on it to catch the door though.

I'm only on the third or so firing of my heater and I'm not using full loads so as to gently bring it up to temp/cure it. I haven't burned much in a stove before, so starting fires is a learning experience (read: I can barely get the thing burning). The build came out decent--I just placed the facing bricks against a cardboard spacer (removed as I went along), so they aren't the most even--I should have used speedset mortar & straighter cardboard. With plastering though it should come out smooth. I'm happy not to have stacks of loose bricks in my 'house' any more.

I think in order to convince someone to purchase your kit, you'd need to make sure the frugality of it doesn't hamper the usability (like the handles). A tried/tested design would go a long way in convincing someone it'd work for them.

 

[byQ]

The parts,

*Traditional fireplace clean-out door - $35 (I will weld a 'wheel' to the screw for quicker opening/closing)
*Hardware, ~$100 (2 small clean-out doors, air inlet door, & air damper)
*Firebrick, - 300 brick @ $1 each = $300
*Refractory Mortar, 2 buckets = $100
*Refractory Cement, 2 bags = $75
*Gasket material between core and shell = cardboard, so free
*Ceramic paper for gasketing = $50
*Outer material = ~$100 (includes old brick to surround flue)
*Flue = 15 clay pieces @ $10 each = $150
*Hi-temp Silicone = $40
*Non refractory Cement, eight 94# bags = $85

total = $435 + $225 + $275 = $935

2 basic ash clean-out doors (5"x5")



1 damper for 8" clay flue


1 Air door


Our Masonry Heater Door, 12" x 12" (we'll weld a wheel to the screw for easier opening/closing)



We can go gather river rock for free for the outside, or find some free or cheap clay brick. Or we could use some other dense stone we find. (note: no sand stone because it may crack/explode.)

Now that we have all of the parts we have to make sure we have a good foundation - so pour a concrete footing a couple of feet deep and add some rebar to it.

This heater won't have a grate (the ash will need to be scooped out).

 

[bholler]

I guess I don't understand. All masonry is homemade. Porches, foundations, fireplaces, etc. Way to big, heavy and unstable to factory build a masonry fireplace. There are metal fireplaces that are factory built, but masonry is built on site, by hand. Rocks and bricks are cut, mortared together and wala!, a fireplace.

nope there are lots of prefab masonry fireplaces out there

 

[bholler]

Are you guys really proposing loading wood through a standard cleanout door? Really? I think you need to seriously re think that one.

 

[byQ]

Observe this door on a masonry heater from Sweden (a tile stove). A traditional door is big enough to let you put your wood inside the firebox. A 12" x 12" door gives you enough of an opening to do this. Also I would place the door in such a way so it was above the firebox floor so you are building up when you are loading your firewood.

I compared this clean-out door to the masonry heater door I bought, and of the two I found the clean-out door to seal better and to be more sturdy. The only problem is the screw-in for opening and closing. I was going to weld the screw to something like this. So you could spin the wheel quickly to open and close.

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[bholler]

*Traditional fireplace clean-out door - $35 (I will weld a 'wheel' to the screw for quicker opening/closing)

Where are you finding a gasketed 12 x 12 clean out door for $35? $119 is the cheapest I have found the door you have pictured. And I still don't think it is big enough. Yes you can load wood through it but I think it would be very frustrating.

 

[byQ]

There is this big movement going on in wood burning regarding rocket mass heaters though you don't hear much about it here. But masonry heaters are a better way to burn firewood. It is the cost that is the problem. This heater proposal hopes to show that a great burning highly efficient wood burner can be had at a reasonable price. This heater option is probably geared to the DIYer. I don't think they would need much masonry experience. If a kit was put together with pieces marked and instructions were detailed I think a 'normal' person could assemble.

 

[byQ]

Where are you finding a gasketed 12 x 12 clean out door for $35? $119 is the cheapest I have found the door you have pictured. And I still don't think it is big enough. Yes you can load wood through it but I think it would be very frustrating.

I don't remember it was a private seller. I bought 3 for $80 (including shipping). And the seller said he had many more. It was a few years ago. Why would it be frustrating? You want an intense short fire - this favors smaller pieces of wood (and fir & pine). Even still a 6" thick piece of firewood should fit easily through a 12" opening. I think the not being able to see the fire as a bigger issue.

 

[bfitz3]

The original post made me think this was a contest/challenge. Either way... Very interesting. Such a stove is on my mind for my someday-I'll-build-it cabin.

 

[byQ]

Here is an eco firebox in action (thanks mha.net).
Why is it more effective (the most effective way to burn firewood)? You can see the little slits in the firebrick - air is coming through these slits. How? The air is coming up through the air grate and going into a hollow door frame and then goes through hollow passages between the two brick layers and out through the little slits in the firebrick. These slits are made by placing little shims between bricks when laying them.

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[branchburner]

It is the cost that is the problem. This heater proposal hopes to show that a great burning highly efficient wood burner can be had at a reasonable price.

My fear as a DIY project would be the approvals needed by building inspectors, insurance co., etc.
I wonder how many insurers would even know what a masonry heater is or how to classify it, as it's obviously more than a fireplace but not a UL-listed wood burning device.