rocket heater - with a hint of pellets

[adam1181]

Hi All, I've been looking at natural draft and gravity fed pellet stoves as a form of heating for my garage.

So today i get the welder out and made this.

 

[Mick - Ford Focus]

Welcome To The Forum adam1181 Interesting Design - Tell Us More.

M

 

[adam1181]

Thanks for the welcome, I've been lurking for a while and enjoying myself looking at all the cool projects on here where i got alot of inspiration.

I currenly work servicing and repairing log and pellet boilers so i get wood pellets for nothing and wanted to play with some ideas to heat the garage in the winter.

I did go down the route of a gas bottle wood burner inside the garage but it smokes abit which the neighbors moan about and i have to chop and store firewood,
This is quick and simple to fill with pellets, light with a blow torch and no smoke at all.

It's early days with the design, i plan to try heating a radiator tomorrow using a pipe wrapped around the flue (open vented to be safe) hopefully it wont cool the flue too much and cause burning issues. i plan to drill extra holes in the burn chamber to get more out of it too.

For a first try today i'm well pleased with the result.

 

[Mick - Ford Focus]

Been There With Radiators At A Mates Shed - Around Flue Proved Inadiquite On His Set Up - Ended Up With A Boiler Heat Exchanger Directly In The Fire Of A Gas Bottle Wood Burner - Blooming Scary Stuff But Ran 5 Decent Size Rads.

M

 

[500e]

Mate runs a wast oil burner with about 20 turns of 12 mm copper central heating pump to 2 4Ft rads 20 gallon header with mains feed + hot water tap works well.
Yours looks simple & interesting a fuller description please

 

[adam1181]

So today the plan was to increase the amount of holes in the burner and try the water heating idea as i already had the rad, pump and pipe so it was worth a shot.

I drilled the holes in the burner and wrapped some pipe around the base of the flue, plumbed to a rad and pump with a header tank and fired it up.

I was really supprised how quick and easy it lit, when i lit it yesterdey i lit some sticks first and pushed them to the base of the flue to pre warm it and get the draw going.
Today i loaded the burner, put the blow torch on for a couple of mins and it was off.

The water heater didn't work too well around the flue as you'd said Mick, i took it off and wrapped a longer pipe around the burner but as it was very very hot and i couldn't get a tight fit on it so that didn't work too well either.
I really want to find a way of heating water with it, i know a few people with swimming pools and have been asked to make pool heaters with gas bottle wood burners a few times.

Next plan is to wrap the pipe around the burner but tighter and more of it but if the water heater doesn't work out then i plan to make a more compact version that can live indoors.

On a plus side adding more holes to the burner has increased the temperature of the horizontal pipe to 450'c but i did run it for longer today so it probarbly would have been hotter than the 218'c it acheived yesterday.

see pics from today, any ideas welcomed.

 

[DrNik]

Why not clad the horizontal tube with a Metal box as a heat exchanger, and fill with water, that way there is only 1 piece of metal between the flame and water so is in direct contact

 

[the snooper]

the way the larger boilers heat water (double throw boilers) they have the fire chamber which then returns through a series of tubes twice, once back towards the burner then back towards the flu to transfer heat to the water

 

[rtbcomp]

Why not clad the horizontal tube with a Metal box as a heat exchanger, and fill with water, that way there is only 1 piece of metal between the flame and water so is in direct contact

And lag the outside of the water jacket. A closed system with Fernox or something in it should prevent corrosion.

 

[bigegg]

Why not clad the horizontal tube with a Metal box as a heat exchanger, and fill with water, that way there is only 1 piece of metal between the flame and water so is in direct contact

The idea of a rocket heater is that heat is removed from the exhaust, rather than the burn chamber - this improves efficiency of the burn to the point where nothing leaves the chimney except steam, and CO2, and heat.
I recommend enclosing the horizontal tube and about 18inches of the flue with a metal box filled with insulation - perlite, vermiculite or blanket, then adding a heat exchanger above this, on the flue.
The hotter the exhaust, the more heat you'll get into your radiator.
Lots of good info at aprovecho.org and on the "permies" forum (www.permies.com)

 

[bigegg]

The hotter the exhaust, the more heat you'll get into your radiator - and a good rocket stove will burn out the horizontal steel tube in a couple of days - DAMHIKT