Batch box heater using fisher stove

Dec 22, 2018 19:49:02

Just finished my batch box rocket heater. It is not a mass heater though, just designed to heat up garage. Used a mama bear fisher stove, easier for our skill level and has the advantage of a well made box with a nice door. Batch box is kinda short, only 15 inches deep and 12 inches wide and 12 inches tall. Port size is 2.5 inches wide and 9 inches tall. Riser dimensions is 6 inches by 6 inches and is square and is 50 inches tall. Used six inch exhaust and it worked out just fine. No secondary intake, not sure I'm going to add one. Didn't insulate riser either. Fire brick for riser was standard, non insulated.

Dec 23, 2018 09:08:59

Hi Jeff ;
Neat little rocket stove you built. I see one major problem. Your barrel is still painted!!! When that heats up, it is going to give off vast amounts of noxious smoke, really nasty stuff!!! I know its in a shop but still...

If that barrel is not getting hot enough to burn off the paint then your not reaching rocket temps.

Its still a neat stove and if its doing the job of heating your area then it will do. Considering its mid winter any working stove is better than none.

Dec 23, 2018 09:53:24

Hi Jeff,
Looks nice, I'll give you that. The top of the firebox is restricted/lined with firebricks but the sides of the firebox are still steel as I see it. Lining this also with firebrick, full or split ones, would help a lot in burning temperatures and through that, cleaner burning. I fully expect insulating the riser as well would raise efficiency again, gaining more heat out of the same fuel.
All that done, you would be able to add a second barrel to extract more heat. And burn the paint off, no doubt, I sincerely do hope you have doors in front and rear of your garage to vent the muck outside.

My original 6" development model started with one 55 gallon barrel and ended with three of those, while the first one already impressed me no end.

Dec 23, 2018 19:46:57

Hm, neat. Now I'm trying to remember how big these Fishers got while retaining the handy 'more deep than wide' style.

Peter, if it's like the old Fishers I've seen, the bottom and sides already had firebrick, and that steel bit at the bottom of the 'roof' bricks is what held the side bricks in place.

Dec 25, 2018 10:11:48

thomas rubino wrote:Hi Jeff ;
Neat little rocket stove you built. I see one major problem. Your barrel is still painted!!! When that heats up, it is going to give off vast amounts of noxious smoke, really nasty stuff!!! I know its in a shop but still...

If that barrel is not getting hot enough to burn off the paint then your not reaching rocket temps.

Its still a neat stove and if its doing the job of heating your area then it will do. Considering its mid winter any working stove is better than none.

Do you have any suggestions on removing the paint? Sander, grinder, paint remover? Top of barrel is 550 degrees so far, don't know how much hotter it will get with that much surface area.

Dec 25, 2018 10:15:31

Peter van den Berg wrote:Hi Jeff,
Looks nice, I'll give you that. The top of the firebox is restricted/lined with firebricks but the sides of the firebox are still steel as I see it. Lining this also with firebrick, full or split ones, would help a lot in burning temperatures and through that, cleaner burning. I fully expect insulating the riser as well would raise efficiency again, gaining more heat out of the same fuel.
All that done, you would be able to add a second barrel to extract more heat. And burn the paint off, no doubt, I sincerely do hope you have doors in front and rear of your garage to vent the muck outside.

My original 6" development model started with one 55 gallon barrel and ended with three of those, while the first one already impressed me no end.

Thanks Peter, the sides are firebrick, the metal is just a brace holding the firebrick in place. As far as insulating the riser, once the riser reaches a certain temp, won't it just stay there? I would think that insulation would just allow it to reach temp sooner, correct?

Dec 25, 2018 10:28:15

Insulating the riser would allow reaching operation temperature sooner, but that's not all. Insulation has also the effect of getting higher temps so more volatiles will combust almost spontaniously.

Jan 17, 2019 17:25:10

Hello Jeff, do you have any pictures of the stove without the barrel so i can see how you configured it? I currently heat my split level ranch with an old fisher woodstove and am contemplating building a RMH but not sure what route i want to go. I figure if my old Fisher can keep the house cozy by giving off 250 to 300 degree temps, certainly a RMH could do that and much more at less the cost - and no creosote worries. More pictures the better...thanks!

Mar 10, 2019 20:25:49

I am new to this but really like the idea you have using old stove as batch box had anyone else done this? I would like to try this but would insulate the riser as well

Mar 12, 2019 10:06:53

Nick Kendall wrote:I am new to this but really like the idea you have using old stove as batch box had anyone else done this? I would like to try this but would insulate the riser as well

Yes. I've used a Charnwood Country 4 as the basis of a BB Rocket.

It's quite heavily modified though... To follow as closely as possible the dimensions on the Batchrocket Resources site, I had to cut off the rear of the stove and extend the depth of the firebox. The whole of the original stove is heavily insulated with insulating firebricks and superwool - there is no metal from the original stove (apart from the cast iron door) that is in contact with the fire. It's a 5" sidewinder system that I use to heat water and a brick bell. It works really well and is into its second winter with only a few issues.

Mar 12, 2019 15:20:58

Do you have any pics This seems it would be easier for me to modify a heater like this that has a nice door and latch setup Vs starting from scratch as I want a nice door latch setup and want bigger then just using a 6 “ design and I want to turn it into rocket stove like the first one in this post

Mar 13, 2019 05:01:40

I have a few Nick and once I've worked out how to share them on here(!) I will...

Mar 13, 2019 05:07:49

Hi John;
When creating a new post, to add photo's you click on the box that says attachments. Then click on the new box that's says upload a file. That should take you to your photos

Mar 13, 2019 05:28:15

Ah right - thanks Thomas.

I thought I would have to link to some photo sharing site or similar on the web. When I return to base I'll give it a go

Thanks again.

Mar 13, 2019 06:00:48

Here's a photo upload test - fingers crossed...

Mar 13, 2019 18:06:03

Thanks
Mind why does the box get insulated? I had thought riser was insulated

Mar 14, 2019 03:53:44

If the firebox was left uninsulated the high temperatures needed to help promote clean combustion would be hard to achieve.

Additionally, the firebox (if made from steel) would degrade very quickly under the prolonged exposure to high heat. There are quite a few threads on the forums showing catastrophic failure of metal components in rocket stoves.

Mar 14, 2019 07:52:55

The entire combustion core, firebox and riser, needs to be insulated. Not only do you want to keep heat inside until it has finished burning, but you need to protect the steel enclosure from exposure to the intense heat.

Mar 14, 2019 08:05:11

Thanks for clearing that up for me

Feb 01, 2024 19:09:20

Cool looking stove. What you have built is a wood stove with a heat exchanger. I have thought about doing the same project: taking a stove like yours and making a BBR out of it. I was inspired by a series of videos on youtube where a gut did this. He cut a hole in the back of his stove and build his riser out of b brick outside the stove. It worked well. I think that you could do the same and plug the exhaust port on the top and exit out the back. Here are the links.

https://www.youtube.com/watch?v=Es0j9xbeyzA&t=85s

https://www.youtube.com/watch?v=j4_ctq2r3Gw&t=11s

Feb 01, 2024 21:03:34

Erin, thanks for the links. I thoroughly enjoyed watching those. But where is Part 3 -- where they fire up the whole thing?

Edit: Here it is. I hate cliffhangers!

No holds barred. And no bars holed. Except this tiny ad:

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https://permies.com/wiki/gear-reviews