Rocket Mass Heater for my home

[matt walker]

Oh, I forgot to mention wood use. I haven't evaluated it again since it's dried out more. I do think I'm using less wood, significantly less, I believe. However, I have my old wood cart loaded with a load that would have on average lasted 24 hours in the old box stove. I've split it for the box stove and loaded it as if I were burning the box stove. I'll pull wood strictly from that, split it smaller for the RMH, and see how long it lasts. I'll update again once I have some data to share.

[matt walker]

...and, a pic from last night. As you can see, I need some serious help in the decor department. I keep trolling the thrift stores for a big bunch of matching pillows or cushions, but so far, no luck. I'm not really going for "gypsy caravan chic", but you make do with what you have, right? If there are any seamstresses or upholsterers lurking around here, please help!

[pa_friendly_guy]

I don't see a problem with Gypsy caravan chic , but then again I don't have much taste. lol I was wondering with the blankets and pillows etc so close to the fire box if you have had any concern about sparks popping from the wood? With the rocket effect are all pops and sparks sucked down into the fire tube? With regular wood burning stoves they want a min of 18" in front of the stove door opening of non-combustible material so that sparks etc can't jump out and hit something that would burn. From the picture it looks like you have blankets etc with in inches of the open fire box. Have you seen any concern with spaks from the RMH?

[matt walker]

Yes Guy, it does pop off an ember or two now and again. If I leave it unattended I will cover the fire box or roll the blankets back. While I'm sitting there, it's not really a problem, but I do have blankets that are all natural fibers so that I don't have burn holes in 'em. That said, the downdraft is strong enough that it's pretty uncommon to have any embers at all popping out, but with the right(wrong?) wood, it does happen.

[pa_friendly_guy]

Thanks Matt, That answers the question. You don't let combustibles near the fire when you are not right there in the room. Makes sence to me.

[matt walker]

Here's the view looking into the window on the rocket mass heater.

[matt walker]

A minor update. Stove is working flawlessly. I'm loving it. I have been letting it go out and stay out for longer and longer periods, and I'm dialing in the schedule. The house is staying warm, I'm staying really warm, too warm often, on a very small amount of wood. I need to do some more observations, but for sure way less than half of what I was using before. Not sure how much less, but less than half, for sure.

I made a collar for the feed tube out of a 6" flange fitting. The cobposite is a cool material, but the wood getting stuffed into the opening wears away at any clay in that spot. I put the flange in a few days ago and it's showing no signs of wear. I think I've the final configuration for the feed in this design.

Here's the flange...I just cobbed over it with an inch or so of cob at the feed, so you just see the metal lining the hole.

[pa_friendly_guy]

The metal was a good idea to protect the clay liner. I am pleased to hear that you are using that much less wood. That is truely an amazing number, to be warmer and only burn 1/2 the wood, wow, that is really a great result. The design work, and the time spent hauling and mixing the cob was truely worth it for you. Sounds like you will save that much work in less than a year of burning. Cutting, hauling, stacking and then burning that much more wood takes alot of time and effort. You will be saving time and effort of years with this new system. Congrats on a wonderful project.

[Lollykoko]

Matt, if you have told us how large your home is, I missed it. Or, for a specific question, about how many square/cubic feet are you keeping comfortable with the RMH? 400sqf with a 7 foot ceiling, more or less?

By October we hope to have a place to live at the farm for at least me. Passive solar and RMH's will be the main source of heat. I'm looking at close to 1000 sqf and wonder if three heaters will be adequate (one in main living space, more in bedrooms).

[matt walker]

Lolly, the room it's in is the living room, connected to the kitchen. I cut the wall between them into a counter years ago, so it's now one space about 28' square. That area is regularly 70*f most of the day, and around 62*f in the morning. It is connected to a hallway at both the kitchen and the living room. That hallway has my 28'x20' bedroom at one end, 18'x10' studio at the other, and a dogleg hallway to a bathroom. A couple other bedrooms are kept closed and heated as needed with electric oil radiators. I just checked the hallway thermostat for the unused oil furnace. 67*F out there right now, probably 65*F in my bedroom down the hall.