Rocket Mass Heaters and Masonry Heaters
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I see a couple of videos about cast cores. what's your youtube handle?
AND: Where do you get your sodium silicate? Anhydrous, or as a solution?
Last edited:
NW Walker
Member
- Nov 26, 2012
- 88
Ted, the radiators are metal boxes like I describe in my last post. They are part of my challenge stove but could be used in place of a barrel in a traditional RMH build, as Oak was asking about.
Here's the first of the core videos, link to the riser vid is in the description:
Here's the first of the core videos, link to the riser vid is in the description:
Ah! haha. of course, your stove! 
(facepalm!)
An excellent video. Very neatly done!
I used to make forms for castable at the last furnace manufacturer I worked for (a very small outfit... but it was wonderful to work there!)
We made burner blocks for huge natural gas burners, and would remanufacture induction heating coils.
Do you have a local supplier for fireclay and sodium silicate?
(facepalm!)An excellent video. Very neatly done!
I used to make forms for castable at the last furnace manufacturer I worked for (a very small outfit... but it was wonderful to work there!)
We made burner blocks for huge natural gas burners, and would remanufacture induction heating coils.
Do you have a local supplier for fireclay and sodium silicate?
NW Walker
Member
- Nov 26, 2012
- 88
Thanks Ted. I made that to show folks who live outside of metro areas a way to cast using materials that are easy to source locally anywhere. I'm a long way from a city, but I can have the local sand/gravel/brick supply place special order the fireclay for me. The perlite I get at the local farm and garden store. I use the Furnace Cement as the sodium silicate supply. It's expensive, but anyone can find it at their local hardware store. For more refined builds I do use castable refractory, which I have to have trucked in.
Which refractory do you prefer? We have a lot of different types & different insulating values...
Have you found one that does well with insulating but can still handle direct flame impingement?
I should ask a couple of the mechanical engineers at the shop...
I'm seriously thinking of building a RMH here in the corner of my main room. It's right near the chimney foundation. I could run right up, through the thimble that's already installed, then up & outside.
Where oh where will I put all the STUFF that has congregated there? I have too much stuff, and not enough room.
Have you found one that does well with insulating but can still handle direct flame impingement?
I should ask a couple of the mechanical engineers at the shop...
I'm seriously thinking of building a RMH here in the corner of my main room. It's right near the chimney foundation. I could run right up, through the thimble that's already installed, then up & outside.
Where oh where will I put all the STUFF that has congregated there? I have too much stuff, and not enough room.
NW Walker
Member
- Nov 26, 2012
- 88
One thing about space and RMHs, they are the opposite of box stoves in this regard. They MAKE useable space as opposed to eating into it. You will be able to get rid of furniture as you are always wanting to hang out on the thing. My stove hearth was a dead spot in the room and now it is the most used area. It's actually an amazing transformation and one factor I never considered. Very cool.
As for refractory, I won't give you a brand because you want to source it locally, but density is important. I'm running a 60-70lb/cu.ft. insulating castable, and have tried everything up to the dense 140-150lb/cu.ft refractories that are typical in industrial combustion chambers. Your engineers and the refractory suppliers won't have good advice for you here in my experience. They are used to dealing with large scale burners loaded mechanically and with forced intake air and other such things. I've found the lighter refractories, which they all recommend against, hold up just great to the abuse of the wood in the feed area and the single most important characteristic in my opinion is low mass/high insulation value. Keep in mind we are talking about maybe 4 lbs of fuel at a time, so their abrasion and flame impingement experiences are just way off the scale in comparison. That's my opinion anyway, although I admit I will sacrifice durability for performance in a whole lot of applications. For sure it's worth experimenting with on your own though, especially considering the knowledge and materials you have access to.
As for refractory, I won't give you a brand because you want to source it locally, but density is important. I'm running a 60-70lb/cu.ft. insulating castable, and have tried everything up to the dense 140-150lb/cu.ft refractories that are typical in industrial combustion chambers. Your engineers and the refractory suppliers won't have good advice for you here in my experience. They are used to dealing with large scale burners loaded mechanically and with forced intake air and other such things. I've found the lighter refractories, which they all recommend against, hold up just great to the abuse of the wood in the feed area and the single most important characteristic in my opinion is low mass/high insulation value. Keep in mind we are talking about maybe 4 lbs of fuel at a time, so their abrasion and flame impingement experiences are just way off the scale in comparison. That's my opinion anyway, although I admit I will sacrifice durability for performance in a whole lot of applications. For sure it's worth experimenting with on your own though, especially considering the knowledge and materials you have access to.
Thanks for your advice.
Perhaps a light-weight castable with a ceramic plate at the bottom of the fuel chute for where the wood contacts the bottom of the J-tube? Best of both worlds?
I've looked & looked for barrels in this area. (I burn my garbage, separate the recyclables...). I haven't even been able to locate a decent burn-barrel! Lots of blue plastic barrels.... they seem to be everywhere.
I'll probably end up buying a barrel online.
This is kinda funny though. I installed a pellet stove this year because I've had so much difficulty in finding time to collect, cut, and split wood over the last few years. I'm betting with a RMH I would probably cut my wood usage in at least half though. My old stove is so inefficient, and I'd always have to burn it on a very low draft. Lots o' smoke!
Id certainly prefer to collect my own wood. It's so much cheaper. Maybe next year I'll get the time.
Another question: I've watched every video on making RMH's I can find on YouTube. I don't see anyone laying down foam board insulation under the cobb and against the outside wall. I should think the heat losses to wall & floor (I'm on ground level) would be reasonably high. Do you insulate?
Perhaps a light-weight castable with a ceramic plate at the bottom of the fuel chute for where the wood contacts the bottom of the J-tube? Best of both worlds?
I've looked & looked for barrels in this area. (I burn my garbage, separate the recyclables...). I haven't even been able to locate a decent burn-barrel! Lots of blue plastic barrels.... they seem to be everywhere.
I'll probably end up buying a barrel online.
This is kinda funny though. I installed a pellet stove this year because I've had so much difficulty in finding time to collect, cut, and split wood over the last few years. I'm betting with a RMH I would probably cut my wood usage in at least half though. My old stove is so inefficient, and I'd always have to burn it on a very low draft. Lots o' smoke!
Id certainly prefer to collect my own wood. It's so much cheaper. Maybe next year I'll get the time.
Another question: I've watched every video on making RMH's I can find on YouTube. I don't see anyone laying down foam board insulation under the cobb and against the outside wall. I should think the heat losses to wall & floor (I'm on ground level) would be reasonably high. Do you insulate?
NW Walker
Member
- Nov 26, 2012
- 88
Firstly, don't worry about the feed area and the lightweight castable. It really doesn't wear significantly with the light fuel you'll be using, and different materials in there present their own problems that are much more annoying in my opinion. If things do wear, it's a simple matter of a handful of refractory plastered around inside there once a season as maintenance.
A thought on the above conversation. Probably the biggest pitfall I see folks fall into when making these is to try to imagine all the potential problems and engineer them out before hand. It always adds tons of complexity and usually more problems. I highly recommend just getting dirty and starting down the road towards a system and you will realize a lot of the imagined issues, really aren't issues at all. Not to dismiss any concerns, just saying once you have your first test burn in a mocked up system you will answer a lot of your own questions. Speaking specifically to the casting durability, the number one mistake I've seen repeated is folks casting in hard materials as linings due to durability concerns, and of course the different thermal expansion properties end up tearing the whole thing apart in no time. I know you know better than to do that, but it bears repeating.
Barrels really should be free and easy to find. Get creative, try oil change places, truck service stations near the interstate, material handling transfer stations, heating oil supply yards, etc. Go in person and talk to a mechanic, not the front desk. Wear work clothes and ask about used drums. I have often cleaned out old fuel tanks on boats I was working on, or old heating oil tanks from homes. If I go somewhere there is a large supply of barrels and tell them I'm needing to transfer some old dirty fuel out of a decrepit vessel, folks are usually willing to pass the old drums along. I've never paid for one here, and even when I built a system for a restaurant in Brooklyn I was able to use these tactics to source them. We found a bunch being used at a Hasidic lumberyard for off cut storage and they were more than happy to have us take some extras off of their hands.
As for insulation, yep, it's a great idea. I'd be very wary of capturing foam in there though, even though the mass theoretically stays well below the off gas temp for the foam. If it's cold out and you are home for a long weekend running it hot, the last thing you want is to smell polystyrene fumes and wonder what's going on underneath two tons of mud. I recommend air gaps, and then you can use a radiant barrier on foam if you like. You can set the mass on durarock supported by bricks every six inches or so to provide an air gap underneath. Same goes for walls. That's just one idea, I'm sure there's a lot of ways to go about it. I would just make sure I could get a light/hand/eye anywhere I had the slightest doubts about to monitor temps. If it's on a concrete floor, just mix Perlite into the cob substrate for the bottom 4" and you'll have a well insulated layer to keep the heat in the mass instead of getting dumped into the huge mass of the pad.
A thought on the above conversation. Probably the biggest pitfall I see folks fall into when making these is to try to imagine all the potential problems and engineer them out before hand. It always adds tons of complexity and usually more problems. I highly recommend just getting dirty and starting down the road towards a system and you will realize a lot of the imagined issues, really aren't issues at all. Not to dismiss any concerns, just saying once you have your first test burn in a mocked up system you will answer a lot of your own questions. Speaking specifically to the casting durability, the number one mistake I've seen repeated is folks casting in hard materials as linings due to durability concerns, and of course the different thermal expansion properties end up tearing the whole thing apart in no time. I know you know better than to do that, but it bears repeating.
Barrels really should be free and easy to find. Get creative, try oil change places, truck service stations near the interstate, material handling transfer stations, heating oil supply yards, etc. Go in person and talk to a mechanic, not the front desk. Wear work clothes and ask about used drums. I have often cleaned out old fuel tanks on boats I was working on, or old heating oil tanks from homes. If I go somewhere there is a large supply of barrels and tell them I'm needing to transfer some old dirty fuel out of a decrepit vessel, folks are usually willing to pass the old drums along. I've never paid for one here, and even when I built a system for a restaurant in Brooklyn I was able to use these tactics to source them. We found a bunch being used at a Hasidic lumberyard for off cut storage and they were more than happy to have us take some extras off of their hands.
As for insulation, yep, it's a great idea. I'd be very wary of capturing foam in there though, even though the mass theoretically stays well below the off gas temp for the foam. If it's cold out and you are home for a long weekend running it hot, the last thing you want is to smell polystyrene fumes and wonder what's going on underneath two tons of mud. I recommend air gaps, and then you can use a radiant barrier on foam if you like. You can set the mass on durarock supported by bricks every six inches or so to provide an air gap underneath. Same goes for walls. That's just one idea, I'm sure there's a lot of ways to go about it. I would just make sure I could get a light/hand/eye anywhere I had the slightest doubts about to monitor temps. If it's on a concrete floor, just mix Perlite into the cob substrate for the bottom 4" and you'll have a well insulated layer to keep the heat in the mass instead of getting dumped into the huge mass of the pad.
Thanks! You're a barrel of info. :D (little pun there... )
You made a RMH is Brooklyn? I'm surprised they're allowed there at all. What restaurant?
I am essentially a city-hater. Brooklyn is a noteworthy exception... it has the feel of many small towns all smushed together.
I have a LOT of polyisocyanurate foam board, foil faced. It's good to quite high temperatures, and has an R19 value. I'll have to experiment a bit with temperatures.
You made a RMH is Brooklyn? I'm surprised they're allowed there at all. What restaurant?
I am essentially a city-hater. Brooklyn is a noteworthy exception... it has the feel of many small towns all smushed together.
I have a LOT of polyisocyanurate foam board, foil faced. It's good to quite high temperatures, and has an R19 value. I'll have to experiment a bit with temperatures.
NW Walker
Member
- Nov 26, 2012
- 88
Hahaha, well, I'd be surprised if it were allowed there too. Wasn't my call, I just ran the dumb end of a shovel. And yeah, I live in a tiny town far, far from any metro areas, and feel the same about cities. I loved Brooklyn, I'm going back on my upcoming D.C. trip to see how they are doing.
Here's a pic, the burn works are hidden behind the screening there, and this whole bench is heated....
![[Hearth.com] Rocket Mass Heaters and Masonry Heaters](/talk/proxy.php?image=http%3A%2F%2Fi65.photobucket.com%2Falbums%2Fh228%2Fmremine%2FNYC%2520Rocket%2520Stove%2520Build%2FP1030373.jpg&hash=1302d28316661ad32a17e0a9579fc034 "[Hearth.com] Rocket Mass Heaters and Masonry Heaters")
Yeah, play with what you have there until you know what to expect and are comfortable with it. That's the spirit!
Here's a pic, the burn works are hidden behind the screening there, and this whole bench is heated....
![[Hearth.com] Rocket Mass Heaters and Masonry Heaters](http://s65.photobucket.com/user/mremine/media/NYC%20Rocket%20Stove%20Build/P1030373.jpg.html "[Hearth.com] Rocket Mass Heaters and Masonry Heaters")
Yeah, play with what you have there until you know what to expect and are comfortable with it. That's the spirit!
Hahaha, well, I'd be surprised if it were allowed there too. Wasn't my call, I just ran the dumb end of a shovel. And yeah, I live in a tiny town far, far from any metro areas, and feel the same about cities. I loved Brooklyn, I'm going back on my upcoming D.C. trip to see how they are doing.
Here's a pic, the burn works are hidden behind the screening there, and this whole bench is heated....
Yeah, play with what you have there until you know what to expect and are comfortable with it. That's the spirit!
![[Hearth.com] Rocket Mass Heaters and Masonry Heaters](https://www.hearth.com/talk/data/attachments/171/171780-074eccc0c6de7ec46a42f4a947b4d4da.jpg?hash=jWPQyXME24 "[Hearth.com] Rocket Mass Heaters and Masonry Heaters")
Hello NW Walker!
I know it's been a few years.... could you let me know the name of this restaurant?
I've been in Brooklyn three times since we corresponded, and have wondered about it each time.
I tried to do a search to find it somehow, but most of the links I find on Google just point me right back here to our conversation!
Hope you've been doing well.
I'm still working doing furnace work, for SECO/Warwick. Big furnaces. I just left Brooklyn on Saturday where I worked on a vacuum heat treat furnace. Brooklyn surprises me... how can industry survive there, with the prices? but they do!
Hope to hear from you soon.
Tedinski
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