Small Rocket Mass Air Heater

This seems cool. A rocket heater mini that diffuses heat into the air instead of a thermal mass.
http://www.youtube.com/watch?v=ER3TsTLDZsk

baggetja wrote:
This seems cool. A rocket heater mini that diffuses heat into the air instead of a thermal mass.
http://www.youtube.com/watch?v=ER3TsTLDZsk

Why? The whole reasoning behind mass heaters is:
  -heating air = bad
  -heating mass/bodies = good

It seems to me you loose the whole reason to go rocket heater. The first comparison to make is amount of fuel burned to be comfortable in air heating vs mass heating... the idea of mass heat is to be comfortable at a lower air temp.

Do some experimenting with this or at least visit houses with both types. Compare burn times.... most mass heaters burn only 2 to 4 hours per day.... air heaters go all day.

The only time the fast heating air heater makes sense is when you only want heat for a few hours, such as in a shop.

The one in the video does have some mass, by the way, that fireplace is one heavy chunk of masonry. The rocket burns well, and the long twisty baffle transfers heat to the mass as well as some air. The fireplace flue seems to be sealed off by the pipe which helps too. He makes good use of what he has available. For a straight air heater, look up pocket rocket. They are cheap and they work, but the room starts to get cold as soon as the fire goes out... same as any iron heater.

Heating air is only bad if you have poor insulation and/or your house leaks air. The first winter in my house the furnace would run about 50% of the time that I had it on.  In other words, I was producing heat twice as fast as it was escaping from my house. After blowing in a ton of insulation and plugging up the leaks, my furnace turns on once in the morning before I get up and once right before I get home from work.  It takes several hours for the house to cool off and I cut my gas bill by about 70%.

A Rocket AIR Heater will work fine assuming that the house is well insulated and sealed.

woodlandmonk wrote:
Heating air is only bad if you have poor insulation and/or your house leaks air.

Yup.... I like to breath. I like to have air that does not have too much in the way things like radon gas too. I put leaks in my house for this reason. (I call them open windows) Just personal choice of course, I grew up in a tight, well insulated house and lived with the health problems too. Life is full of trade-offs. There may be lots of people who can take staler air than I can and perhaps a tight house would work for them.

Neat little heater but I'd like to see a rocket stove mass heater that is semi-portable (can be moved). Seems most I have seen are set in place and cannot be moved.

Len wrote:
Yup.... I like to breath. I like to have air that does not have too much in the way things like radon gas too. I put leaks in my house for this reason. (I call them open windows) Just personal choice of course, I grew up in a tight, well insulated house and lived with the health problems too. Life is full of trade-offs. There may be lots of people who can take staler air than I can and perhaps a tight house would work for them.

It shouldn't be said that heating air is "bad".. It's just that air as a heat STORAGE medium generally sucks. No matter how well insulated the house is, the air will deliver the heat to the walls (and roof) and outside faster than slow mass will. Also, hot air tends to go where you don't need it, up in the ceiling or attic.
It seems to me that a rocket stove without the mass would be about as useful (or not) as a well stoked potbelly stove. The thing's gonna be (generally) either too hot or too cold. You will get from a rocket stove a clean burn all the time, which will be good for your local air quality. Unfortunately it will remove one of the biggest advantages of having one in the first place, mass storage and slow constant heat over a long period of time.

As len pointed out, tight houses can cause health problems so maybe not such a good thing..

I give props to the guy.

He applied a lot of clever thinking to come up with something that appears to be so, so much better than the wasteful big-ol buring wood piles that most people have in their living room fireplaces...

It seems to me like heating the air in the chimney is a good way to export the heat from your house.

Emerson White wrote:
It seems to me like heating the air in the chimney is a good way to export the heat from your house.

It's really hard to tell how much of that is happening in this case. If I was doing things that way, I would have sealed the chimney off except for my flue. The old fireplace looks like it has quite a lot of mass, so this is a bit of a mix (like most RMHs) between air heating and mass heating. The mass heating is not direct so will not be as effective the bench in a standard RMH, but the shape of the fire hole it sits in will tend to hold the hot air next to the masonry for better transfer. The long exhaust pipe will radiate at the masonry on three sides as well.... Sort of half way between an iron stove and a RMH.

The plus side is that it makes good use of what is there without making a landlord upset... and it makes much better use of the wood than the fireplace would have.

The only way to tell how good it is (or isn't) would be to measure.

It takes a lot of heat to raise all that heavy exhaust up the chimney.

Len Ovens wrote:

baggetja wrote:
This seems cool. A rocket heater mini that diffuses heat into the air instead of a thermal mass.
http://www.youtube.com/watch?v=ER3TsTLDZsk

Why? The whole reasoning behind mass heaters is:
  -heating air = bad
  -heating mass/bodies = good

It seems to me you loose the whole reason to go rocket heater. The first comparison to make is amount of fuel burned to be comfortable in air heating vs mass heating... the idea of mass heat is to be comfortable at a lower air temp.

Do some experimenting with this or at least visit houses with both types. Compare burn times.... most mass heaters burn only 2 to 4 hours per day.... air heaters go all day.

The only time the fast heating air heater makes sense is when you only want heat for a few hours, such as in a shop.

The one in the video does have some mass, by the way, that fireplace is one heavy chunk of masonry. The rocket burns well, and the long twisty baffle transfers heat to the mass as well as some air. The fireplace flue seems to be sealed off by the pipe which helps too. He makes good use of what he has available. For a straight air heater, look up pocket rocket. They are cheap and they work, but the room starts to get cold as soon as the fire goes out... same as any iron heater.

Actually, heating air =good, when your building can't support mass but is very well insulated, as well as very small. My tiny cabin on a trailer bed cannot hold the mass necessary for a regular mass heater, but this - this I can do. I've already been giving thought to how I'd run pipes, and his video is very helpful.

It's great to hear this, and I'd like to talk with you more about the mass-heating principles in relation to air-heating:

Len Ovens wrote:

woodlandmonk wrote:
Heating air is only bad if you have poor insulation and/or your house leaks air.

Yup.... I like to breath. I like to have air that does not have too much in the way things like radon gas too. I put leaks in my house for this reason. (I call them open windows) Just personal choice of course, I grew up in a tight, well insulated house and lived with the health problems too. Life is full of trade-offs. There may be lots of people who can take staler air than I can and perhaps a tight house would work for them.

Despite that these comments seem a little pessimistic about the masslessness of the heater, in any case I am excited to make a massful heater because I am currently living in a large shed that has quite a many drafts, cracks and holes in the walls --- and none of them are deliberately open windows! Also, the shed is not insulated. In the winter it will be dry (other than pacific northwest 33 degree F humidity), because the roof is great; but the walls are uninsulated and very drafty. Like: cracks in between the boards of the walls, above and below doors, outright holes. Woo! The place is beautiful. And I love fresh air. Anyway, let's see how an RMH does in these conditions. That is, hoping that the RMH is built within the next two months.

Note,

this "Small Rocket Mass Air Heater" concept that is the subject of this thread, might rather be called "Small Rocket Stove Air Heater"

Note that there are Rocket Stoves, and then there are Rocket Mass Heaters. (There are even two separate wikipedia articles). The latter (RMHs) utilize the same 'rocket' concept as the former (RSs), but RMH's have an added twist: the mass.

Eh?

Semantics..

Adam StJohn, you and I are both living in sheds in the PNW, how funny. My shed doesn't have quite the leaky walls yours does, but it isn't insulated OR warm....my little house that I'm building can't do the mass thing, but if I was going to stay here in this shed, I would absolutely make one.