Wood burning boiler

[Lewist123]

Thanks for the comments guys.

I ran it again tonight with no baffle at all, and although it smoked a little less, it burned cooler and I had lots of wasted fire out of the chimney.

Here is a video I took of it last night compared to my BBQ oven. The smoke from the bottle burner isn't bad but if I can do better I would like to.

Please excuse the heavy breathing in the vid, I had just been cutting some wood and it was cold. Also please excuse the messy garden. A bit of a spring cleaned ended in more mess!

Also have a few pictures of the last bits of progress

 

[Lewist123]

Here are some pictures of the flue and test burns 1 & 2. I made the flue by cutting 500 mm longx 100 mm wide strips of 3 mm steel and welding them up into a box section.

As an aside, these are my favourite cutting disks. Anyone found these good/anything better?

This is test burn 1 with the angled baffle and tube intake

Here you can see fire licking past the tube and baffle, but no combustion within the baffle void.

Here is a picture of test burn 2. I took the secondary air feed pipe off so I could see more what was going on inside

Here is an attempt to photograph the smoke.... it doesn't really look bad at all, and it may be this is the best I can hope for.

P.s. I have a video that shows the smoke MUCH better. In contrast, there is the BBQ oven running.

It is in a different league!!

Lewis

http://www.youtube.com/watch?v=3srScibtjtY&feature=youtu.be

 

[@Turbo]

looks good to me. why are you so worried about the smoke?

you could put a water jacket around the flu if you wanted.

 

[Lewist123]

Right then guys.

I have been play around and I have success!!

I added a rear air intake up from the bottom up to just under the baffle, as well as tweeking a few other bits. I also got a 3m length of 6 inch duct to act as the flue.

I just tested it and it basically went mental! Glowing bottle etc and almost no smoke at all. Just stupid amounts of heat.

YAY!

Now to finish the burner, and then seal it into the air tank water jacket. With any luck I will be ready for a test of the boiler early next week.

Thanks for all the comments and suggestions.

Lewis

p.s. some more pictures soon.

 

[Mick - Ford Focus]

Good Stuff Lewist123

Piccys Yes - We Need To See What You Changed.

Mick

 

[@Turbo]

awesome glad it worked out, keep us updated

 

[Lewist123]

Right, evening all.

Sorry for the delay in updates, but I have been all over the UK on site visits recently, so evenings have been very busy.

So here are a few pictures of the test burn I did the other day, the one that worked!

Here is the burner without the flue.

You can see just heat haze, NO smoke. This is just what I was after

Here you can see the 150 mm steel ducting flue

Right, here are the modifications that I made. I added a secondary air intake feeding air into the back of the burner and up behind the baffle.

I tweeked the baffle, and added a flair to the front edge to help hold the fire below the baffle to mix with the extra air. It seems to do the job.

I then started to double weld everything (inside and out) that I could

I then set about welding the top on

Cleaned up

I just need to clean all the old burnt paint off, and give it a few coats of high temp paint to help slow the rusting down once bathed in water. I just hope it is water tight!!!

Lewis

 

[MattF]

Out of curiosity, how are you planning on sweeping that flue, when necessary? Looks like your baffle is blocking rod access from inside.

The reason the intake down the bottom worked is that you're heating the air, the reason why the front intake didn't work. The secondary combustion relies on highly heated gases. The front intake air would always have cooled the gases, whereas the bottom rear intake is heating the secondary combustion air supply up before it hits that area around the baffle.

 

[Lewist123]

Matt, the flue pipe comes off, leaving the short square section sticking out of the burner open. If need be I can brush that out by hand before putting the long duct back on.

As for the air intake, indeed the front one didn't put air in the right place or at the right temp!

Thanks

Lewis

 

[Lewist123]

Right. a bit more progress.

I sanded the old paint off and gave it a coat of BBQ high temp paint. I layed about 10 coats on the weld joints to help ensure that any pin pricks are blocked (I really do hope it holds water!).

I then set about cutting more out of the old air tank to enable me to slide the burner section into place.

Cut out of the rear air intake

It has spread a lot now that I have cut the sides, so I will need to ratchet strap it back into a more round shape before welding the front back on.

Starting to weld the burner into the tank

Tacking the rear strip back into place.

More pics soon.

Lewis

 

[Lewist123]

I cut a flue hole in the air tank lid

I also finished welding up the gaps in the front and back

Then out of the shed to test water tightness so far.

Filled with water

A small leak from the air tank out, but NO water in the inner burner. WOOP (so far!)

Lewis

 

[dunc78]

The reason the intake down the bottom worked is that you're heating the air, the reason why the front intake didn't work. The secondary combustion relies on highly heated gases. The front intake air would always have cooled the gases, whereas the bottom rear intake is heating the secondary combustion air supply up before it hits that area around the baffle.

I am making a burner out of 6mm Plate, I am wondering what is the best place to have the secondary air feed fed to, just below the baffle plate so it is still in the flames or above the plate, so it is mixing with the smoke?

 

[MattF]

Below the baffle plate, towards the front edge of the plate. This is a worthwhile read too:

http://www.aprovecho.org/lab/pubs/rl/stove-design/doc/18

 

[dunc78]

Below the baffle plate, towards the front edge of the plate. This is a worthwhile read too:

http://www.aprovecho.org/lab/pubs/rl/stove-design/doc/18

Thanks Matt, that looks like a good resource.

 

[Lewist123]

That is a great read, thanks. I have seen that somewhere before, but only taken the time to read it properly today.

Some updates soon. It is almost done!

 

[Lewist123]

Well today I finished welding most of the top of the burner on and then hooked a hose up to test it out.

Still leaking out a bit, but NO leaks into the burner

Test fire

NO SMOKE yay!

It makes a good quantity of really really hot water

Video to come soon too.

 

[Lewist123]

http://www.youtube.com/watch?v=no8Sc9wKp3Q&feature=youtu.be

Video link

 

[@Turbo]

good job. now al you have to do is get it connected to the house heating.

 

[Lewist123]

Right, time for a bit of an update.

I gave the boiler a very quick and dirty lick of paint to stop the worst of any rust forming on the joints.

I then had a test burn. I used the pump from an old washing machine to move the water from a plastic storage tub (just temporary) through the boiler.

Here is a video of it in action. It seems to be working really really well. Lots of hot water, and quick too, without the use off too much timber. Also there is a lot of heat loss due to the lack of insulation.

http://www.youtube.com/watch?v=0qbDG457m74

 

[Lewist123]

Time for another quick update.

I have been looking around for a suitable water storage tank. I think a 200 ltr oil drum is a bit excessive, so purchased a 100 litre dustbin. I was a bit worried about its heat resistance, but the plastic seems more than able to deal with the hot water (I had a test burn).

I drilled a few holes in the bin and added some fittings. I will plumb it in better once in the shed, but this worked well enough for a test.

I also got a small rad off a friend. Fitted into the shed, just needs plumbing an controls sorted out.

Here is another test video

http://www.youtube.com/watch?v=3dHmvvI3zrQ&feature=youtu.be