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Integrated Rocket Mass Heater

Posts: 56
Location: Eastern Massachusetts
fungi wofati bee
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Hi Folks,

I posted something in green building about slip form and hempcrete so I'll omit those questions, however it prompted another idea which I added in as an edit to the bottom that pertains to this forum so I thought I would re-post here. I apologize if I am posting incorrectly.

My questions are:

How feasible it would be to integrate during construction one or more rocket mass heaters into a slip form structure, either a green house or a home?

If it is would the thermal mass provided by the stone and concrete increase the heat retention or would most of it already be lost to the room via the bench?

Furthermore would it even be possible to get such plans OK'd by building inspectors/ dept of making you sad etc?

Thanks for your time.

Posts: 1288
Location: Okanogan Highlands, Washington
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those are three questions from a huge range of fields.

- We generally don't like integrating structural components with heater - it makes it much harder to repair or modify the heater if something comes up. Most masonry heater builders recommend making the masonry chimney separate from the heating channels, so you don't have the entire weight of the chimney supported on the masonry heater and can get in there for repairs.
I especially want to be able to get at the barrel/bell in case of repairs, since a neglected building might easily have a rusty or dented barrel while everything else is in good working order. Even packrats in the manifold will make you wish you could take the barrel off easily.

But you can easily integrate the thermal mass beside / between the load bearing masonry walls, in thermal contact, such as rocket benches running alongside cob walls at Cob Cottage Co. I don't even mind putting the pipes directly in contact with load-bearing masonry, and mortaring around them, as long as the load is not supported on the pipe itself. You might have to watch for cracks between new material and old if they were built at separate times, or on separate footings.

- The thermal mass of the building itself tends to store a lot of lovely heat as well, both from the barrel and in contact with the mass. Our concrete floor slab, for example, gets warm enough to make a palpable difference even through wooden flooring several feet from the heater. How much heat and at what temperature depends on a lot of other building factors.

- Permittable?
Look at ASTM standard E-1602 for masonry heaters, design your build to meet it, and also inquire whether your local jurisdiction has ever heard of such things.

Some jurisdictions have banned wood heat altogether, due to prejudice, lobbying, or a history of local bad habits.
Some jurisdictions don't require any permits at all for residential construction, or for projects that meet certain weight / square feet criteria.
Some are conscientious but ill-informed, resulting in an expensive appeals or variance process in which a large committee of government-employed engineers, lawyers, and citizen volunteers gets educated on your dime.
Some cities have friendly public-interest committees that sit around and educate themselves about new or enlightened technologies for free, and sponsor your approval process with donated expertise.
Sometimes it's even helpful to ask your home insurance company first - they may be able to give you more specifics, faster.

So the short answer is "it depends whose permission you are asking for."

There are standards to meet that should make it do-able, but the vast majority of current owners have either gotten bogged down in the permitting process and built anyway, or didn't bother with permission.

Erica W

edited for brevity and compulsive rephrasing
Posts: 3241
Location: Southern alps, on the French side of the french /italian border 5000ft elevation
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My opinion kind of differs to Erica's.

I have only a few rockets ;without mass; under my belt.

But if i had my own place, i would realy like to make an inside wall into a big bell and insert a batch rocket inside it. Two layers of bricks, separated by a foot or so. One batch rocket tucked in there with it's mouth flush to the wall. One chimney at the other end, with two ports. One up top, which can be open to prime the chimney. One at the bottom, to make the wall act as a bell. Can be made into several heat traps, etc. I would may be make just a tall bell above the heat riser, and then a lower one goint to the chimney, with wall mass above the low bell.

This can be all made with half barrels into a mud wall too. There would be no wuick heat with this design. Tho, an idea which occured to me, a window could be cut through the wall, where the heat riser is, and covered with a steel plate bolted to the wall. Which would act as a radiator, like the barrel. And also could be taken appart for inspection.

A 6 incher batch rocket can cope with 5 M² on internal bell surface area. So far, i don't have data from any of the guys at Donkey's site for an eight incher.
Daniel Clifford
Posts: 56
Location: Eastern Massachusetts
fungi wofati bee
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Thank you to everyone I really enjoyed your responses, and I am currently redesigning much of what I had I mind before. Erica you are definitely right in that it is better to ask for forgiveness rather than permission.

I still want to build my own home someday and incorporate an integrated heating mass possibly including a bell or walls with a rocketmass heater where the rocket, riser etc. could all be exchanged and or cleaned. Elaborate but I like the idea, anyways thanks everyone hope you are all having a good holiday season.
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