Thread: Oil burning shed heaters

Originally Posted by Ralph1Malph

Build not going so well.
Can't get the draw right (maybe flue too short) and really have to get the lower chamber really burning hard before any sort of combustion happens.
Gunna fiddle around with the lower chamber tomorrow as I believe all the oil is burning there, not as it goes up the secondary chamber as it should.
Obviously, got a prob with air flow too, but we'll persevere.
There were moments of success but few and far between.

I'll endeavour to play by the rules and post a few pics tomorrow too.

Ralph

Hi
My flue, 6 inch, is approx 3.5 metre's and works great. When i built my prototype to test the idea it was 4 inch and about 2 metre's that worked well also? for the air entry into the primary pot iv'e got 4 x 17mm holes

You'll work it out and it will work reliably

Cheers db

Originally Posted by Ralph1Malph

Build not going so well.
Can't get the draw right (maybe flue too short) and really have to get the lower chamber really burning hard before any sort of combustion happens.
Gunna fiddle around with the lower chamber tomorrow as I believe all the oil is burning there, not as it goes up the secondary chamber as it should.
Obviously, got a prob with air flow too, but we'll persevere.
There were moments of success but few and far between.

I'll endeavour to play by the rules and post a few pics tomorrow too.

Ralph

If your oil is burning in the lower chamber, it sounds like you have too much air going in there through the primary air holes. I have six holes of 6mm diameter. Remember, you only need enough air in this part of the burner to vapourise the oil in the bottom.

Also it sounds like you are leaking air somewhere and losing your draft. Normally if you have too much air in the primary burner it will roar like hell and you'll have lotsa black poo tinkee smoke.

Orright,
Pics to follow but we are nearly there.
Spent a week fiddling and today we built to spec.
Using a galvanised washbasin about 14" dia as lower pot.
Machined a lip into 10mm plate for the lid and bottom plate.

I only have 110 mm pipe so the flue is 2.5m of this.
Two truck brake drums form expansion and radiator chamber.

Here's where it gets weird. I have 4x 8mm holes in bottom plate and secondary burn chamber is 4-5" 130mm pipe...but it seems to work best with only 8x 10mm holes in a ring about 2/3 way up.

With this config, we could get a sustained secondary burn with vclean emmission. Interestingly, it was almost silent, no vicious induction noise as with prototypes.

Will fiddle more tomorrow, as this trial was with the lower pot about 1/3 full of oil (2.5 litre). It was hot enough to peel the paint and grime from the brake drums and 1.5m of flue, but after 1 hour, nowhere near cherry. BTW, by my reckoning, it burnt about 1 litre per hour so happy with that.

I also made a trial secondary chamber with approx 40 holes but simply could not get it to secondary burn. It's also cool when the oil in the lower pot crackles and boils (not good but we made it happen).

Happy with the build so far but something still not quite right. Even though burns clean, I was seeking a more forceful, hotter burn.

Any tips anyone?

Ralph

I hope that you are not going to use it with the primary pan containing any depth of oil. Should you get a bit of water in the bottom, it will eventually boil and the oil will literally erupt. It could be very dangerous. My experience with only a few millimetres of oil in the bottom containing a teaspoon or less of water were alarming to say the least. It crackled and roared belching black smelly smoke out of every available orifice, it also spat droplets of smoking and burning oil out of the secondary air holes. fortunately they were small and never made a lot of mess but the smell was bloody horrible.

The idea is that once burning, the fuel is only added at the same rate at which it burns so there is rarely any measurable amount of oil in the pan except a small pool immediately under the feed trough

As for the configuration of your holes,... "If it works and does not smoke or smell, you must have it right. Obviously you have discovered another working combination.

Eureka!
Have stumbled upon the correct ratio of holes, air, flue, oil etc.
Works well, and clean too.
Now just putting on some legs and better arranging a dripper and *hey presto* should be ready for the final modification.......
Oh and pics when finished.

Ralph

It's great when it happens.

I'm sure you'll enjoy working in your shed a lot more now. I'm really looking forward to the pics.

Great news do you have an estimate on litres/hr i'd be interested to compare I run around 2.5/hr

look foward to seeing your pics

db

Originally Posted by db65boxer

Great news do you have an estimate on litres/hr i'd be interested to compare I run around 2.5/hr

look foward to seeing your pics

db

Very early trials indicate around 1.5 litres an hour, but I expect that will go up a little as I have not bothered to fine tune too much.

Hope to have it home this W/E and put to use....I have added some bits to suit my purpose. Have to wait and see

Ralph