masonry heater flue materials?

I don't have the floor space for a RMH bench and would like to build a masonry heater as simple and cheap as possible. I don't want to build the whole flue out of fire bricks if it's not really needed. Can I use regular cinder block bricks with holes in them or the cast fireplace chimney flue sections? How far down the flue line from the burner can those be used due to heat? thanks Alan

Alan Mikoliet : Welcome to Permies.com, and a Warm Welcome to the permies Rocket and Wood stoves Forum Threads, With over 19,000 members world wide you should be
able to come here 24 / 7 and find someone who wants to talk about what you want to talk about, Your fellow members will have widely, even wildly varying view points that
will stretch your mind ! Lets jump right in !

Unfortunately, all Concrete Masonry Units C.M.U.s contain lime, which starts to breakdown at Temperatures around 400 F, Famously, paper ignites at 451 F, You will have to use
Brick for the structure, and fire brick for the combustion chamber, marrying the two requires expansion joints with out the proper placement of which you will be well and truly
fucked. If you are off by one brick you are fucked, by the time you have created a working unit you will have good brick laying skills and know enough about types of mortar to
carry on a conversation with a union mason !

At the top Right of this page between the permies sponsor banner, and the video of the day is the Permies Tool Box, update your personal information to include your local region,
you may have a near neighbor that teaches brick laying, and then go to the search Ap and click on it! On the next page, enter Masonry heater, Russian masonry heater,D.I.Y.
heater, and then select a Google search here in permies, it will hook you up with a list of threads will those tag words !

Another good place to look is at the bottom of this page in the area labeled 'Similar threads' after the computer gets to know you your picks down there get better! Hope this helps
/will get you started !! For the good of the crafts ! BIG AL !

Allen, I updated my profile for area, and your tip on similar threads has paid off on this thread already with the masonry bell heater. Very simple and if it works I might build one. thanks Alan

Al 2 Al : It didn't take look at yours spot under your name, and look at mine ! Big AL

Alan Mikoleit wrote:I don't have the floor space for a RMH bench and would like to build a masonry heater as simple and cheap as possible. I don't want to build the whole flue out of fire bricks if it's not really needed. Can I use regular cinder block bricks with holes in them or the cast fireplace chimney flue sections? How far down the flue line from the burner can those be used due to heat? thanks Alan

Alan, are you still going to build a masonry heater? I live by Twin Falls, Idaho, and I am building a small house and am going to build a masonry heater, too. I've been studying up on how to build a masonry heater "as simple and cheap as possible". I've learned some things. Fire brick must be used in areas that get hot (like the firebox), but regular brick can be used in areas that get warm, only (like under the firebox).

I've got most of the parts I need - fire bricks, a door, a grate, 2 clean-out doors, air grate/door, bags of refractory cement, and a couple buckets of refractory mortar. I still need a damper. I've been reading and asking masonry builders questions for the last year or two.

The door for a masonry heater can be expensive $400-$2000 but one could use a large clean-out door (15"x 15" outer dimensions) for a door (less than $100). I got super duty fire brick via an auction and saved on these. Where you are you should be able to get beautiful free rock for the outside of the heater (river rock looks awesome).

I haven't been focused on the flue yet but mainly the heater. I purchased the plans from the masonry heater association. I'm going to build a medium sized contraflow heater, going for simplicity - no bake oven, no bench, just the heater. P. Mason

Tom, Yes I am working on a hybrid heater using aspects of all of these - RMS, Masonry, Bell, and Double barrel wood stove. I created a build thread for it. Yes we have rock on our property that could be used. I am currently laying out the horizontal batch burner and riser. Sounds like you are paying too much for your hardware. Try to custom make it.

For those in Idaho. Are you getting a permit? I'm trying to get a permit for one in Canyon County and they have no idea what I'm talking about.

Paula Crawwford wrote:For those in Idaho. Are you getting a permit? I'm trying to get a permit for one in Canyon County and they have no idea what I'm talking about.

Paula are you looking for a building permit for a masonry heater or a rocket mass stove?

Alan Mikoleit wrote:I don't have the floor space for a RMH bench and would like to build a masonry heater as simple and cheap as possible. I don't want to build the whole flue out of fire bricks if it's not really needed. Can I use regular cinder block bricks with holes in them or the cast fireplace chimney flue sections? How far down the flue line from the burner can those be used due to heat? thanks Alan

Most people use stainless flue for the chimney. Take a look at the builds from MHA (Masonry Heater assn) which are all high mass designs. I thought at first this was to meet code, but it seems the reason it so the flue cools faster after the burn so it stops sucking warm air out of the home because of chimney effect. In Europe they block the flue after a firing 100%, but in North America this is not legal and the flue may only be closed 80% to prevent stupid people (or smart people being stupid) from killing themselves. Shutting the air intake is OK though. Europe has a long tradition of properly using masonry heaters, but North America does not, we brought the oversize mostly ineffective, fireplace from the UK and so the iron wood stove seems really good ... But is still not very effective. There are a number of masonry heater plans around, some very well designed, to get a building permit pretty much requires a certified mason and a double skin. I think that the certified mason does not have to actually build it, but does have to understand and approve your plan. He probably also needs to inspect your work and sign it off. This may mean more that seeing it after it is built The MHA does offer courses and is able to certify masons.

If you are not getting a permit, there are single skin designs from Russia that can be home built for similar price to a RMH. Same number of fire bricks and either common brick for the rest or adobe brick (like cob hand made bricks).

Tom I'm wanting to build a rocket mass heater. There are no regs for one in this county. I was hoping to find regs in this county at least for a masonry heater since they are similar but no luck there.

I have been trying to find codes from other places to show them and hopefully get approval.

I am just beginning my research on masonry heaters. Has anyone had experience in eastern WA (specifically Whitman County) of getting these approved?

Laylah Sullivan wrote:I am just beginning my research on masonry heaters. Has anyone had experience in eastern WA (specifically Whitman County) of getting these approved?

Hi Laylah, My name is Tom and I live over near Twin Falls, Idaho (not too far away). I'm building a medium sized house. I've decided to build a masonry heater to heat this house. Hopefully next year I will build the heater (foundation done so far). Here is what I've learned/done so far,

* The masonry heater's association www.mha-net.org has the most information on masonry heaters.
* I presented my house plans and the masonry heater building plans I obtained from the MHA to the county building department.
* I got the ok to build a masonry heater from the plans however the county instructed me I needed to show them how I was going to support such a heavy thing (up to 12,000 pounds) in the house.
* I'm building a concrete slab - 4" thick - and where the masonry heater sits the slab will be 10" thick with reinforcement. The county was good with this.
* I'm going with a smaller masonry heater, should weigh 5 or 6,000 pounds.

A masonry heater is safer than a fireplace or a RMH because the fire is enclosed. It is safer than a wood stove because it is much thicker with and inner layer of fire brick and an outer layer of brick or rock. And a MH only requires one or two 2 hour fires a day instead of 24/7 burning of wood like a wood stove.

If you are building a new house you will need to have a concrete slab or footing where the MH is going. I've seen where metal braces/supports have been used, too. I've been figuring out how to build a MH for about $800 - that is a 100% functional MH. The way I am saving $$ is,

* Building a smaller contraflow style MH (2'x3'x6.5') which will require less materials (about 60% less material than the large contraflow MH). Reasoning? - My house is passive solar and well insulated so this smaller heater should be fine although in the winter I may need to fire it twice a day.
* Using a large cast iron fireplace clean-out door for the masonry heater door - my cost $43. It is 100% functional but no you won't be able to see the fire. The door has a 12" x 12" opening (big enough). A cheap masonry heater door with glass is $600 and expensive ones are $2000.
* Outer material - by flexible here. Free river rock of the proper shape and size work fine (no sand stone, granite types are good). Or reclaimed brick works good. I've gathered reclaimed brick for $20 and for free. I went to a rock quarry and for $20 they let me pick through there discard pile of stone. Stones in the 1 to 4 brick size that are 3" to 5" thick are ideal - I found lots of these. The quarries commonly discard this size for being too small. The stones are nice with at least 2 straight edges and flashy colors.

Fire brick is a must and unless you can find it used and clean you will have to shell out $200 to $300 for it. And you will need a bucket or 2 of mortar (~$50/bucket), and a couple bags of refractory cement ($50/bag). There are a few others little parts needed like clean-out doors and an air inlet but that is most of it. Of course there is a lot of physical work collecting stones/bricks. And It may take some time to build. But a masonry heater that is well constructed is a very good (the best in my opinion) way to burn firewood. I hope I've helped!

oops, tried to post some pictures but they didn't work.

Tom Quinn wrote:oops, tried to post some pictures but they didn't work.

I would be interested in seeing your progress as you go about this. Keep us posted if you can.

Thanks!

I'm a potter and have a couple of ideas. One is go to the axner pottery web page and look at kiln furniture. You'll see kiln shelving there. Kiln shelving is a high alumina type product sold in differing thicknesses and is available in large pieces. Cost may be an issue and in that case look at a product called rock wool. Rock wool is a refractory insulation. put a stainless pipe within a larger carbon steel pipe (double containment basically) and pack the space with rock wool.

Potters tend to build a lot of stoves and heaters as they build kilns. They are constantly looking for better ways to fire their ware - it's in their blood. And we are all broke, so we tend to be pretty thrifty.

One other thing to know is that stoneware fires up at 2K without issue and it's cheap. You could have a potter throw you a stoneware cylinder and glaze it with a cone 8 glaze for next to nothing. It would hold up to temps in excess of 1200 degrees F. It would not melt until it reached 2K F, and even then it would reconstitute. You'd have to let it down slow to prevent shatter, but that should really not happen. Shatter is why you would use stainless steel - if that was an issue. ALL masonry has has a limited life when heated and cooled over and over.

Three product ideas that may offer creative thinking though. Use schedule 10 304L stainless pipe (do a search on "pipe valve and fitting industrial suppliers" ). Use rockwool between two substrates. Use a stoneware cylinder (must be stoneware). Terracotta will burn.

Potters dabble in that sort of thing constantly so the pottery websites may spark some ideas too

Doug