My first two builds.

Posts : 9 Join date : 2013-12-05

My first build:

Built from a 19kg gas bottle. Heat riser is 3 and 3/4 inch stainless tube, 5mm thick with about an inch and a half of perlite insulate. Temps on the top are too much for the stovax spring thermometer, the dial reaches the end and stops so I have no accurate reading as yet however the max on the dial is 900f so this thing kicks out some serious heat. Exhaust temps as they leave the heat exchanger are around 170f. Secondary air and vortex are incorporated in to this build but the secondary air is not functioning correctly and must be redone, I have an idea in mind which I shall share if successful.

Cost of stove to build: About £25 sterling.

Second build:

Built from an old bollard I picked up at the scrap yard for a few quid. Heat riser is the same as used in my first build however in this stove there no insulation. The stove if lit with finely split wood will burn smokeless instantly and seems to burn cleaner than the first stove. The temps are off the dial again with this one but this one actually burnt the paint off the stove thermometer so it must be getting even hotter. No secondary air on this one but it does have a vortex built into the riser/burn chamber. Although this stove functions very well I do feel that it has much room for improvement. The exhaust temps are a little higher with this one at around 200f, I guess this is because there is no insulation on the riser/burn chamber.

Cost of stove to build: About £15 sterling.

I mostly burn pallets in these stoves and use approximately one and a half pallet a day between them, lighting them at around 7am and running them until roughly 11pm.

Admin Posts : 913 Join date : 2013-10-07

Man I really like the second stove that you made! Looks like a nice compact footprint.

Something like this would be great for a mass heating system, looks like a small powerhouse.

Subscribers Posts : 333 Join date : 2013-10-07

Nice stoves. What are the dimensions of the top stove's combustion chamber? In the second stove you have higher temperature at the chimney because your heat exchanger has a "small" volume. Would it be bigger, gases would have longer time to expand and release more energy to the environment.

Posts : 9 Join date : 2013-12-05

Trying2Hard wrote:: Man I really like the second stove that you made! Looks like a nice compact footprint.

Something like this would be great for a mass heating system, looks like a small powerhouse.

Ye I really like that one too although I am not so keen on the drop feed even though I can achieve a 4 hour burn if I load it right, I just dont feel like I can leave it for more than a few moments at a time and have had a few back draft issues because of the weird wind eddies I get here, nothing I can't address though!

caotropheus wrote:: Nice stoves. What are the dimensions of the top stove's combustion chamber? In the second stove you have higher temperature at the chimney because your heat exchanger has a "small" volume. Would it be bigger, gases would have longer time to expand and release more energy to the environment.

Thanks. The dimensions of the fire chamber are H: 6 inches, W: 5 inches D: 10 inches. I intend to enlarge it for longer burn times.

Admin Posts : 241 Join date : 2013-09-30

Both stoves look to be working great, nice idea bolting the top stoves two sections together.
As caotropheus says the higher flue temps on the second one are due to less heat being extracted by the stove body or exchanger.

Posts : 9 Join date : 2013-12-05

Ye the insulation is loose around the burn chamber so I couldn't perma seal the lid as I need access to it fairly regularly, it is also still in a state of observance as I consider various adaptations.

As for the other stoves flue temps, I recognise that the heat exchanger is not as efficient being so tight to the riser. There is also no insulation on the riser or burn chamber so the core of the fire is right next to the flue exhaust sending very hot air up the exhaust, kind of a double whammy there. It originally had a 3" riser which sent a lot less heat out the exhaust but it did not acheive the temps I wanted on the stove.

The base of the stove stays quite cool, do you think if I put the flue exit at the bottom of the stove, well below the combustion area that it would still exhaust properly? Or would that choke it? If it works it would cool the exhaust temps a bit more and also draw more heat to the lower part of the stove. Any thoughts on that would be welcome.

I would just try it but I don't have access to a suitable work space at the moment.

Admin Posts : 241 Join date : 2013-09-30

"The base of the stove stays quite cool, do you think if I put the flue exit at the bottom of the stove, well below the combustion area that it would still exhaust properly?"

you might draw a bit more heat out doing that, welding fins 3-4 inch wide an inch apart the length of the body around the outside of the body would probably cool the flue down more and give alot more output.

Subscribers Posts : 333 Join date : 2013-10-07

smiff

Take a look at this channel. You can see how this guy build his stove. He also had a problem of a chimney exit lower than the combustion chamber and he had to build a bypass to start the fire and then close the bypass to operate the stove in regular mode.

https://www.youtube.com/user/JeffCBodine/videos

Interesting to see how much below the combustion chamber you can place the chimney and still allow the stove to work efficiently. Together with some fins, just like ppotty1 said, you can achieve nice heat output.

Posts : 9 Join date : 2013-12-05

Interesting solution with the T section and butterfly damper, I think I will try that. And three or four 3 inch wide fins running down the full length of the back side of the stove. It will be interesting to see what happens.

Thanks for the input fellas.

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