Why dont we all want rocket mass heaters?

[begreen]

If done well I would expect a rocket mass heater to approach or be similar to the performance of a good masonry heater. But there is no magic here. There are only so many BTUs in a cordwood log. If the place can be heated with a few logs a day that means that either the area heated is small, or well insulated and/or the differential between room temp and outside temp is low. One can not achieve greater than 100% efficiency burning wood, which is what some claims suggest. 90% is pretty darn respectable if that can be achieved.

 

[georgepds]

Why don't we all want rocket mass heaters?

1 performance is unsubstantiated hype
2 butt ugly
3 not ul listed
4 won't get past the building inspector
5 half the posted builds say they don't work ( see #1 )
6 I don't want to learn how to build with clay and straw
7 can't insure the install
8 there are good stoves that work commercially available

But for those who like to tinker, tinker away.

 

[byQ]

This discussion has made me realize something. Suppose you had 2 woodstoves with cats, 80% efficient, stove A and stove B. Stove A was just a normal wood stove. But stove B was constructed with metal chambers. There was a chamber in the front constructed into the form of a chair. And a chamber in the back constructed into the form of a bed. Let's say someone did the math and figured how to keep this chair and bed from burning your hide. Maybe by using more than one layer of steel/cast iron or using soapstone.

Well, people spend an average of 8 hours in bed and several more hours sitting. Because stove B has a more direct path to heating people wouldn't it use less firewood, even though both stoves are 80% efficient? I wonder how much less firewood?

 

[begreen]

For a long time Russians built beds onto the top of their masonry fireplaces. That place was usually reserved for the grandparents. I assume this was out of kindness, but the venting on these fireplaces was often terrible, especially if you were poor, so the higher up in the room the worse the smoke. That might explain the low life expectancy of these people.


Here is a high-end model.

 

[maple1]

This discussion has made me realize something. Suppose you had 2 woodstoves with cats, 80% efficient, stove A and stove B. Stove A was just a normal wood stove. But stove B was constructed with metal chambers. There was a chamber in the front constructed into the form of a chair. And a chamber in the back constructed into the form of a bed. Let's say someone did the math and figured how to keep this chair and bed from burning your hide. Maybe by using more than one layer of steel/cast iron or using soapstone.

Well, people spend an average of 8 hours in bed and several more hours sitting. Because stove B has a more direct path to heating people wouldn't it use less firewood, even though both stoves are 80% efficient? I wonder how much less firewood?

Sure it would. But the house would be colder. Which is not what was being claimed elsewhere in the thread.

 

[byQ]

The claim - 1/20th the amount of wood and the whole house is 70 F?

 

[begreen]

Not too hard in a small strawbale house when it's 50 outside and the sun is shining.

 

[maple1]

The claim - 1/20th the amount of wood and the whole house is 70 F?

There were a couple. One was house just as warm on 1/10 the wood. Another was 3 bedroom leaky house at 69 throughout all winter on 0.6 cord. Might have been more.

 

[blades]

Advertising hype- got your attention didn't it , there for it worked, product might not but that is of secondary importance to the advertising agency. Marketing 101

 

[Seasoned Oak]

No way id be satisfied to burn wood and live in the 60s all winter. its got to be 75 to 77 or ill go back to oil if i want to be cold all winter. All the work of a wood stove but not the bone warming effect of a wood stove dont make sense to me.

 

[georgepds]

No way id be satisfied to burn wood and live in the 60s all winter. its got to be 75 to 77 or ill go back to oil if i want to be cold all winter. All the work of a wood stove but not the bone warming effect of a wood stove dont make sense to me.

Actually, more work...you have to split the splits into tiny sticks

 

[georgepds]

For a long time Russians built beds onto the top of their masonry fireplaces. That place was usually reserved for the grandparents. I assume this was out of kindness, but the venting on these fireplaces was often terrible, especially if you were poor, so the higher up in the room the worse the smoke. That might explain the low life expectancy of these people.
......

Beats putting then on an ice floe and pushing them out into the winter sea

 

[peakbagger]

I have seen and heard of good Russian fire place designs and bad Russian fireplace designs. Most of the time you hear about the good ones, rarely do you hear about the bad ones and most of the owners of the good design are not your typical 9 to 5 homeowner. I ran into someone on my travels who had a "good" design". He and the wife were retired and keep the unit fired as needed so i was always warm and their firewood was well seasoned and dry. It was great except when they went away for few days or weeks. Unlike a wood stove that would be cranking out a lot of heat in an hour or less when they got home, it took a real long time like overnight for the russian fireplace to be putting out heat. I know of a couple bad designs where the pressure drop for the internal passages exceeded the available draft from the chimney Net result getting a fire going was very difficult. In one case I heard of is the mason came in with a jackhammer and went in through a clean out port and jack hammered a bypass between the firebox flue and the main stack to get it to run. It would run once they took out all extra resistance but it was an awfully expensive exercise. I have heard of at least two others over the years that got jack hammered out.

Reminds me of the oil fired electric radiator scam. The selling point was the radiator gave off heat after the power was off. The trade off was it took longer to warm up. There were all sorts of claims as they being more efficient but given that electric heat is effectively 100% efficient, kind of hard to get much more, unlike the fabled amplifiers from Spinal Tap, efficiency doesnt go to 11

 

[begreen]

The Russian bed fireplaces are different from the more modern Russian fireplaces. We have several in our local area due to Wesleyans living here a while back. They had some master masons amongst them and the fireplaces they built are excellent heaters. I have been around a few of them, one at all times of the winter. Built right, they work well and are quite easy to run.

 

[maple1]

That could be pretty risky business for a home owner, with either a Russion/masonry heater, or a rocket mass heater. If it doesn't get done right and work right it's pretty hard to do over.

 

[Seasoned Oak]

Reminds me of the oil fired electric radiator scam. The selling point was the radiator gave off heat after the power was off. The trade off was it took longer to warm up. There were all sorts of claims as they being more efficient but given that electric heat is effectively 100% efficient, kind of hard to get much more.

Still dont know what the selling point of the Edenpure is . $300 for a 1500 watt plug in electric heater. Lots of knock offs for under $200 still highway robbery.
The only unsung hero in small electric heaters is radiant. I have a 500 watt ceiling radiant ($39) but need to be installed, that warms a large bathroom with no other heat source, comfortably all winter. Its only in use when occupied.

 

[georgepds]

.... efficiency doesnt go to 11

Except ,of course, for heat pumps

 

[georgepds]

Still dont know what the selling point of the Edenpure is . $300 for a 1500 watt plug in electric heater. Lots of knock offs for under $200 still highway robbery.
The only unsung hero in small electric heaters is radiant. I have a $500 watt ceiling radiant ($39) but need to be installed, that warms a large bathroom with no other heat source, comfortably all winter. Its only in use when occupied.

Can you identify the model?

I'm looking for one

 

[Seasoned Oak]

Can you identify the model?

I'm looking for one

The radiant heat bathroom ceiling is sold under Nutone and also Broan.
(broken link removed)

 

[Seasoned Oak]

Well, people spend an average of 8 hours in bed and several more hours sitting. Because stove B has a more direct path to heating people wouldn't it use less firewood, even though both stoves are 80% efficient? I wonder how much less firewood?

If it were just about warming you while you sleep ,they have electric blankets and electric mattress pads that use a few pennies a day for that. You would still wake up to a cold house ,in which you do not want to have to be limited to sitting in your warm chair all day in order to keep warm. What your trying to achieve can best be done with higher levels of insulation. A smaller home very tight and well insulated has a very small heat load. sometimes only 10 or 15K Btus an hour. Solar exposure can help a lot as well. In such a place just the heat from people and appliances,cooking ect, at times are enough. Iv done it so i know it works.

 

[Dantheman300z]

Sure it would. But the house would be colder. Which is not what was being claimed elsewhere in the thread.

Maple1: If you notice one of Paul's other posts it is a video of the 87% electric bill cut/ or heating bill. Pauls house in other rooms will be colder because he uses lights and lamps as heat, has a heated keyboard and other devices. So his main room will be 69 degrees but he learns to cope with other room colder.

I like Paul, I read his forum and this one, only two things I do much in the Internet. He does have some very good ideas.

 

[Seasoned Oak]

Pauls house in other rooms will be colder because he uses lights and lamps as heat, has a heated keyboard and other devices. So his main room will be 69 degrees but he learns to cope with other room colder.

That provides more clarity, He is not heating his house to 69 Deg. with just .6 cords of wood. He is heating 1 room to 69 with .6 cords of wood and the rest of the house with electric to less than 69. A small cat stove might be able to turn in close to those numbers, although would have to be a very small stove to heat only 1 room to 69 or less.

 

[peakbagger]

Dick Hill had a combination masonry heater/wood stove he was experimenting with in his final years. I expect it would be very similar in heating efficiency to a rocket mass heater. http://www.hotandcold.tv/masonry_stove.html. His innovation of using a stainless steel screen in place of an actual catalyst was ingenious and cheap. I think his building was a much older home that would be far less energy efficient than a newer one so his total heating demand would be higher. He was also quite active but elderly at that point and expect that he probably maintained a higher heating temperature than 69 degrees. That's the problem with trying to compare fuel use and efficiency for a cyclical heating source, unless two identical spaces are built with the same solar exposure, climate conditions with equivalent thermal mass and then maintained at a set temperature for a long period with different heating sources any comparisons are apples to oranges. Good for bragging but not so good for real data points.

 

[Seasoned Oak]

This kind of heating is being done every day with a gassifier boilers and storage. The hot water storage taking the place of tons of masonry. Many similarities, including clean burns, high combustion temps and not having to fire it every day on milder winter days. Although no one is claiming extremely low wood use with these systems.

 

[maple1]

This kind of heating is being done every day with a gassifier boilers and storage. The hot water storage taking the place of tons of masonry. Many similarities, including clean burns, high combustion temps and not having to fire it every day on milder winter days. Although no one is claiming extremely low wood use with these systems.

Yes, that's another point. I replaced a very inefficient wood/oil combo boiler with a gasser + storage. The old one was about as inefficient as you could get, boiler wise. Everything else remained the same. So I sort of did the same thing as would be done by replacing an inefficient wood stove with a very efficient burn+storage RMH. Sure, I saw consumption drop, but nothing like the touted 1/10 claim. I think I cut my consumption by maybe 25-30%, but also saw a somewhat warmer house, I think. So realistically speaking, a 1/2 reduction claim may have been believable assuming a very inefficient stove as baseline. But 5x that much, uh, no - everything else is definitely not remaining equal.