Uncle Mud Tiny House Rocket Mass Heater 1 Year Update--The Long Firegeek Version

Heating a Tiny House with wood is something of a challenge.  There have been at least eight attempts to build a successful heater for this particular tiny house. I am proud to report after a full heating season that for the first time this building has a super efficient, clean burning heater that doesn't leave the room like an oven when you first fire it up in the evening or dead cold when you wake up (or both). The feedback has been positive from multiple guests, some of whom have never operated a woodstove before.   #unclemud #rocketmassheater #rocketheater #cob #tinyhouse #wheatonlabs

This is neat!

About how much does this mass weigh?
What is the size of the house (square footage and height)?
How is it insulated?

Great video, Uncle Mud!

I had always wondered about the risk of pillows on a rocket bench - better to know that's a fire issue than not know. Your overall, clear explanation of fire risks from heat build up and repeated heating of wood, is really important for people who haven't grown up with wood heat.

Your explanation of "burn time" vs "mass heating time" is also something that often gets glossed over when people are looking into how to heat a space. Thermal mass is wonderful for some situations, but can be a detriment in others. This is why house RMH's have lots of thermal mass, but shop RMH's often don't. We want nice, long lasting heat in our houses, but if we're only going to be in the shop for 2 hours, let's get it hot fast!

Keep up the great work!

That stainless barrel has got me drooling...they are not easy to find over here.

Hi;
Interesting build.
I just did a rough, guesstimate on my (new) materials cost to build something similar:
$C3088
Scavenging would lower some costs, but takes time in a low population area; stainless steel barrels are not common.

I  wonder about the space; from the video it seems the installation + offsets takes about ?3' x ?10' which seems a fair share of the tiny house.

Estimates (in Canada, we still use imperial for building supplies.):
Stainless steel barrel, 50 gallon, $C1250 (ULine.ca)
8" stove pipe (black), $C23/18" x ~30'/1.5' ~ $C460 (HomeHardware.ca)
6" stove pipe (black) $C24/36" x ~ 10'/3' ~ $C80 ((HomeHardware.ca)

8" stove pipe take outs $C57 x 3 = $C171 (HomeHardware.ca)
8" stove pipe elbows $C25 x 2 = $C50 (HomeHardware.ca)
6" stove pipe elbows $C20x 3 = $C60 (HomeHardware.ca)
6" to 8" stove pipe increaser $C29 = $C60 (HomeHardware.ca)
8" rain cap $C37 (HomeHardware.ca)
Aluminum foil tape ~ $C24 (HomeHardware.ca) (adequate?)

SteelSheet 24GA 0.024 $C0.03/sq inch x (48" x 24") x 2 ~ $C69 (metalsrus.ca)
(There may be cheaper appropriate heat shield materials?)
Pea gravel x 0.24 yard ~ $C30

Uninformed guesstimates on quantities
2" thick 2600F wool forge liner 12 sq ft $C216 (https://canadianforge.com/)
9" x 4.5" x 1.25" firebrick $C9 /each X ?20? $160 (kent.ca)
2" x 4" x 8" brick $C3.33/each x ?100? = $C333 (kent.ca)
2" x 4" x 96"  lumber $C4.4 each x ?20? = $C88

Phil Stevens wrote:That stainless barrel has got me drooling...they are not easy to find over here.

I doubt it would be cheap, but in Ontario, Canada, and probably east and south of here, bigger maple syrup operations use them for shipping syrup. Perhaps occasionally they have a discard for some reason.

Phil is in the manuka honey producing country of the world , they might be using s/steel barrels for storing /shipping --as its required for high value medical and human consumption food products---any damaged one would be rejected for further use.

tony uljee wrote:Phil is in the manuka honey producing country of the world , they might be using s/steel barrels for storing /shipping --as its required for high value medical and human consumption food products---any damaged one would be rejected for further use.

Brilliant suggestion...and the honey industry is on the skids at the moment and going through a major contraction, so there could be some excess inventory around. Most of the commodity liquids used by farmers like glycerol, molasses, and all the milking plant chemicals like teat spray and descaling acids are packaged in plastic drums. Specialty products like manuka honey would be the exception.

i bought 2 s/steel drums some years back from a guy who used to supply the "winegum /pastile" making sweet industry with natural fruit juices---from bramble fruits and elderberry---all hand picked by locals in the season--they only used s/steel --no plastic --not even hdpe---unlike the factory i worked in decades ago ---importing mushrooms in brine --shipped by sea  from the other side of the world---took months to arrive ---we had to open up the drums and tip them into vats---foaming up inside ---they were sliced and steam cooked in jars ---for sale at your favourite shops.

Yes, there is  a royal dignity to the SS barrel, and prices for them here had me scratching my head.... are these barrels actually platinum instead?

Has anyone tried using a repurposed industrial barrel, then using a sheet of 30 Guage SS to create a second layer?  An air space between could also inspire increased air circulation,  it seems.  That might be kinder on the bank account

I've had good results just coating the exterior of a plain steel drum with linseed oil. I do it once a year on average and that keeps the rust down to a very minor feature, mostly cropping up because the RMH is in a glasshouse and sits next to a bathtub with a recirculating pump and slow sand filter, so the odd splash can happen. Nine years of service so far, and I replaced the top with a piece of heavy steel plate so I'd have a better cooking surface and because that part of the drum was spalling after a few years of use.

Phil Stevens wrote: I replaced the top with a piece of heavy steel plate so I'd have a better cooking surface and because that part of the drum was spalling after a few years of use.

How did you do that? Weld it in? How thick is the plate? I haven't built a RMH (yet!), but as I consider it I've wondered about whether the top would wear through from the intense heat, and also how to make it an effective cookstove, so this is of great interest to me.

Andre Wiederkehr wrote:

How did you do that? Weld it in? How thick is the plate? I haven't built a RMH (yet!), but as I consider it I've wondered about whether the top would wear through from the intense heat, and also how to make it an effective cookstove, so this is of great interest to me.

Yes, the top will deteriorate from the heat. The middle of mine developed a few transparent spots by the time I replaced it.

I had a circular piece of 6 mm mild steel plate cut by someone with a CNC plasma rig. When I removed the remnants of the original drum top, I left about 2 cm around the outer edge and put a piece of fire rope in the indentation to seal it. The plate just sits on top and its weight seals things nicely. The photos should give you an idea how it fits together.