Heater for 200 ft square cabin.

[Chrish]

Greets

Been reading this board nightly. In the process of finalizing the design for a small well insulated cabin that is 200 square feet. Would like to use a rmh to both heat the place as well as water. Everything I've read so far is fascinating but I'm thinking over kill for such a small cabin. The smallest design I've come across is the 4" unit on wheels but there is no data on output. In and ideal world I would like to go to bed at night without stoking the fire..) Any advise or recommendations would be greatly appreciated for this small living space

[mannytheseacow]

Welcome, Chrish. A 6" J is probably the minimum, with an 8" being even better. Even in a small space you will benefit from being able to use a variety of sizes of fuel and burn to heat as needed. As long as you have a large mass you will only being burning for long-term radiance anyway, so you could probably get away with very long spans of time between burns (ie. 12 hours or more, depending on the climate).

And that is just considering ambient heat. If you want to heat water through a thermosyphon or something similar an 8" is probably the way to go. Adding a bypass flue with water heating coils could be really promising for you.

[Chrish]

Thanks for your reply and aplogies for my delay but working on one bar in the woods..) Was wondering if you have any design or plan recommendations for both the heater and thermosyphon system. Have worked out some preliminary drawings based on an 8" system but two things are scarce to find; natural clay still on the hunt for that and older bricks without holes. Tending to favour a steel based system but still on the hunt for materials. Want to keep the costs to a min if possible. Again many thanks.

[4seasons]

In order to help we would need a bit more detail. Area in which you live will help determine climate and materials that may or may not be available. 200 sqft of well insulated cabin is not a lot to go on. A 200sqft log cabin with 6 inch walls and dual pane windows on a concrete slab in southern Texas is going to need almost no heat compared to a tin carport with fiberglass insulation sitting on a frozen lake in Minnesota.

[Chrish]

Yes of course.

Climate data:

http://www.eldoradocountyweather.com/ca ... water.html but we had a one in one hundred year winter last year and the same is expected this year due to what's happening with the Pacific currents.

Cabin construction is all rough cut dimensional pine 10x20 with a roof truss system. All pine no OSB anywhere. Floor walls and ceiling insulated to R20 and all wrapped in Tyvek and 6mm vapor barrier inside. Insulated floor rapped in Tyvek ad well to prevent rot which is a problem here and the real 1x5s for flooring. A solid little cabin.

One metal in swing door and two windows on the short sides and one next.to the door. All are double pane and e glass so filled with some innert gas both salvaged from returns.

Building will contain a rmh and a 200 gal drinking water tote on a crib at ceiling height to give pressure water system.

Building will be used to build skin on frame kayaks and a warm comfy bed as needed.

Will be steam bending green ash for ribs and comings so if I can get both hot water and steam out of the system feeding the steam chamber that would be the ideal scenario.

I'm sure can find clay it's just a matter of how far is a reasonable drive given the cost of gas at >4 bucks US a gallon. Lots.of clay 2 hrs north of me. Fire bricks are 3.99 for the thin ones and 5.99 for the thicker ones. Refactory cement is about 70 bucks CDN for a 30Lb bag. Old soft.bricks can be found in Halifax at 50ents a piece and it's a 1.5hr drive.

Contacted several local chimney and stove repair companies and told them I would gladly take all the old stove pipe saving them a dump run.

Still looking at designs and reading up on stuff. About where I'm at, at present.

Ideally I would like to place.the 4x4 tote and heating system along the 10 foot wall as that gives me the largest shop area. That wall when finished will be 9-2 as using rough cut lumber.

[Nirky]

I heat my 500-sq ft home with a 6" J RMH and love it. I am planning to build a 12x16 office out back, and it's heat source will be a small wood stove like a Jotul. Sure I could engineer and install a smaller footprint RMH, but it would take up more valuable space.

[Chrish]

Which of the many plans did you follow?

[Nirky]

I chose Matt Walker's 8" cast core design:
https://www.youtube.com/watch?v=7ANMXGrxgnE

[Chrish]

Been looking at Matts cabin stove ver 1 and 2. The info on both states that the stock temp is around 300 degrees. Was wondering if that heat can be redirected and retained in another mass somewhere close to the stove.

Also cant afford stainless loop to heat water at this time bit with that stack temp a heat exchanger made of copper coils leading to a vertical column thermo syphon should or could work. Any thoughts or comments on either issue?

Best and thanks

Ch.

[mannytheseacow]

Hi Chrish, yes, I think that is the whole beauty of these stoves- you can redirect that clean heat through a mass. Matt would probably have better input on how adding a mass would affect how finicky his cabin stove would be, but simply by using a bypass it could make good use of that heat when needed.

As far as the water heating, running a thermosyphon between your water tank and the stove will work beautifully for you. A copper coil works nicely, here's a link to mine:
You may consider something I've always wanted to try- simply bury an old radiator off of a vehicle into your stove or mass somewhere... radiators are cheap salvage, and I bet you could build it right in to your cabin stove somewhere....