Rocket Mass heater

[wayne ollerenshawParticipant @wayneollerenshaw89933]

@Diogenes

And others if any good to them.

 

A while back i had a go with one of them  cheapo chinese diesel heaters. Not much use to be honest and costly to run.

 

So as i built stoves in the past i thought to build another and then came across these Rocket Mass Heaters. Much better on heat output and consumption on fuel. Being wood only a sit burns from the top and not below.

Tis build is same but different as with all these heaters, they work in a similar way a sin ait fed from above into the combustion chamber and has a vortex tube to the heat exchanger.

 

They burn smoke free and on a lot less wood than a normal wood stove due aswell as the wood burning it also burns off the gasses in the second burn.

My no means is this the best set up but works well and give off enough heat to warm 80 cubic meter workshop in well below freezing outside temps. part insulated workshop.

 

i dont have a full build of how i did it but i hope you will get the idea.

roughly 50cm cube exchanger box with part of a 47kg propane cylinder on top. and a 40cm box burn box.

5mm all around for both fire boxs

heat exchanger box

 

Main fire box

 

I dont think tis is a great deal of differance but the combustion air is drawn from the back and below the main box. this is to pre heat the air. the as it enters the fire box it is drawn down as wood burns from above as coal is from below.

 

 

[noel shelleyParticipant @noelshelley55608]

The most important thing with any device that burns is to be able to control the combustion air ! If the fire box is not able to be almost air tight then the fuel will just roar away. Nornal wood burners suffer from air leaks, round the glass, round the door seals, ash pan door if it has one and poorly fitting air controls, top air and bottom Etc. A time expired propane bottle makes a good workshop heater provided you you can control the air in any orifice made in construction. If the flue leaves the fire box horizontally it posible to get single pipe circulation in a 5″ or 6″ pipe where by cool air will enter the fire box  in the lower half to the pipe whilst hot exhaust leaves in the top half allowing the fuel to be burnt with out control – this is where the flue damper comes in ! And yes I know there not allowed any more lest we gas ourselves ! My wood burner would go 36 hours without fueling.

Back in the late 70s there as a heater called a Jetmaster, this was a open fire box with a thin outer skin on the sides, back, top and bottom . This allowed cold air to be drawn in at floor level, circulate round between the firebox and outer skin and exit at the front top. Circulation was achieved by the use of a simple near silent tangential fan unit. Addapting this idea to a wood burner would creat a very efficient heater. Owners of welders, form an orderly queue behind me ! Noel.

[DiogenesParticipant @diogenes]

Thanks very much for taking the trouble, Wayne, it wasn’t a design / idea that I’d seen before, and it’s interesting to see inside it.

..firstly I will have to get round to doing some creative studwork.. ..cheers..

[BazyleParticipant @bazyle]

Regarding air heating mentioned by Noel; my (long boarded up) Victorian bedroom open fireplaces have an external air feed going up the sides of the fire and exiting through a grill above it. The stove I am sitting in front of at the moment also takes room air up the sides which exits over the top of the door. Since the register plate directs the combustion up past this air passage it gets quite hot. This arrangement is very common.

My understanding of a rocket stove is the name is used for a very simple design of an outdoor use stove with a vertical fire tube about 4 in square and another tube welded on at the bottom at an angle of about 45 degrees. Bottom is sealed by burying in soil. Sticks are fed down the angled tube and the fire burns up the vertical in a very directional way so the feed tube is not hot. The name comes from the fierce flames that can come out of the top.

Apologies for HSE diversion: Remember that all your flue paths must be 45 degree minimum not horizontal to ensure that soot build-up cannot block them.

[wayne ollerenshawParticipant @wayneollerenshaw89933]

Morning all.

Sorry for ending the thread so abruptly but internet went off.

 

so where was i

 

Its best to build a riser tube from fire brick but after numerous failed attemps and it costing to much i used a length of mild steel tube. it has lasted well for two winters. but then it doesnt take as much temp as some of these heaters do. max temp i have had is 495 degC. as said its more than enough.

The riser is connected to the fire box by the second burn corridor. this has a taper to create the vortex needed to give the second burn fed from the combustion inlet aswell.

 

rear of the combustion chamber is the flue exit. including a cleaning door.

 

with added fire rope to seal it.

sealed and lined the fire box,

 

also the door to the fire box

 

 

completed and with either a viewing glass to see the vortex or a crucible pot, which i have yet to test. made it for lead and i am wondering if i can do some copper wit help of a blow torch and the exctractor i have to set up for fume extraction..

 

the rest of the pics will not work now on this site, give me a minute

 

 

[wayne ollerenshawParticipant @wayneollerenshaw89933]

not best vortex but that half burn

 

[noel shelleyParticipant @noelshelley55608]

An interesting if not rather complexed design involving a great deal of work to squeeze the last ounce of heat energy from the fuel ! In terms of size rather too large for most small workshops, certainly my 12′ X 16′.  Your mention of melting lead, Yes it should be possible, MP 327c. but copper at MP of 1083c is very doubtful. In terms of colour it is yellow+. For casting you will need a pouring temp of approaching 1200c, almost white heat. Any steel in proximity of these sorts of heat will be plastic, having little strength. You have shown your skill in welding and fabrication, if you wish to try foundrywork build a proper furnace – it will be easier than this fire ! If you wish to discuss this matter PM me ! Noel.

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