John Harrison

Mark - for my BB rocket brick bell I used a cast iron oven door as an inspection door on the front. The added benefit is that it starts to radiate heat almost as soon as the fire is lit.

I also incorporated an old Georgian cast iron oven (with door) into the bell structure which also radiates heat quickly as well.

Glenn's right. You need to have a very hot, highly insulated firebox/riser to burn the wood cleanly first and then target the heat generated towards your heat exchanger.

Any cooling of the combustion area will result in a dirty burn that will smoke like crazy and deposit tar and creosote.

I'm using a conventional 'wrap around' wood stove boiler as a heat exchanger on top of a 5" BB rocket riser to help heat my hot water and provide central heating. The boiler is rated at 45,000 btu/hr and this output, it appears, can be achieved if you keep the firebox well stoked with decent dry hardwood mixed with a little softwood.

The BB also heats a single skin brick bell.

When I get the chance, I'll post details of my build and how the system performs.

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.

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

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.

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

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.

The brick bell on my 5" RMH gets warm right down to floor level when heated for some time. The top is appreciably hotter but the whole bell is providing useful heat.

I'm sure a 'thin' bell (essentially a hollow wall) would be very effective.

Hi Kelly

I think your idea should work, but I would put a 'proper' insulated chimney on the exhaust side to ensure you have enough draw for the whole system.

I would also include an area at the base of the chimney exhaust flue where you could light a priming fire to get everything pulling in the right direction, especially when the system hadn't been used for  a while.