Cold smoking temperatures

[Dick Bee]

I'm starting with the "garden incinerator + smoke generator tube" system. My first attempt was cheese, and I got a fair bit of melting, thick billowing smoke, and a short burn time. I figured that it was burning too hot, obviously, and put it down to excessive air flow. I'd taped over the holes in the sides of the bin, with aluminium tape, and therefore, for my second attempt ( to smoke some chillies), I taped up five of the holes in the bottom, leaving five open. This time I also inserted my oven probe thermometer. The temperature is still getting up to 35C. Too hot still. Should I close off more holes, presumably the smoke generator tube needs some air, so I can't close them all off? The ambient afternoon temperature today is 14C.

 

[Wade]

You have several ways to try to address this problem.and the answer may be a combination of them...

Only half fill the tube

Are you standing the tube upright and then filling it up almost completely with pellets before you light it?

If so then you should try only 1/2 filling it and then  lay it flat and give it a light shake to spread the pellets along the whole length of the tube.

As the tube is now only half full horizontally it will produce less heat as it burns and slightly less smoke.

Use water/ice pan in the incinerator

Place a couple of bricks at the bottom of the incinerator and lay the lit tube between them. Then place a water tray above the bricks and either fill with cold water or ice

Place the tube underneath the incinerator

Raise the incinerator on 3 bricks and then place the lit tube underneath. This will give a larger air space for the heat to dissipate into.

To guide the smoke upwards make a card strip or use a black plastic bag and tape it round the bottom of the incinerator to fill the gap between the incinerator and the ground. Leave an opening though close to the lit end of the tube to allow air to get to the burning pellets. I have not included a picture of this.

 

[Dick Bee]

Thanks Wade. I've raised the incinerator, minus legs, on 8in sleeper off cuts, and put the smoke generator on the slabs underneath. I managed to do so without needing a skirt of any sort. I've left an air gap at the open end of the tube as you suggest, turned away from the breeeze. So far so good! Burning well, temperature in the smoke space is 13C. Much better! One thing I did notice is that the incinerator in your photos has holes under the top rim, and mine doesn't. They may let heat escape.

I'll see how this works. If ok I'll have another go with the cheese, and then, the salmon!

[Wade]

1 hour ago, Dick Bee said:

One thing I did notice is that the incinerator in your photos has holes under the top rim, and mine doesn't. They may let heat escape.

The one in the photos also had holes around the sides too which I sealed with aluminium tape. There are a lot of different designs. I am checking that yours does have a hole or chimney in the lid?

[Dick Bee]

Yes, it has a chimney. I sealed the holes in the side, a double row at the bottom end, same as yours.

[Dick Bee]

Overheating problem hopefully solved!

This is an old galvanised honey extractor, a type illegal for honey use for many years now, and I’ve used as a planter. The bin fits just about perfectly over it, will be sealed with duct tape. Smoke generator can go in the bottom, or raised a bit. It has a honey gate, a big valve, that will serve as an adjustable air inlet.

Edited November 12, 2018 by Dick Bee
Missed a bit out

[Wade]

That looks good and it should work well. All of our cold smokers evolve over time just as yours has done.

I have been using the same cold smoker setup for several years now however the hot weather this summer resulted in smoker temperatures that made it too hot to use. With the smoker located inside the Smokery, and only having a short connection between the smoke generator and the smoking chamber, the internal temperature of the chamber was often over 30 C, even without the smoke generator lit. I therefore redesigned the unit in September and relocated it outside. It now reliably maintains the outside ambient temperature inside the smoking chamber even with the smoke generator lit - and I now often need to use the internal heater.

[Dick Bee]

Impressive looking bit of kit! Mine's bright and shiny now! Gave it a good clean out, blowtorched it to sterilize it, a la beekeeping practice, and found some pin holes where it had rusted. I've now wrapped it with aluminium tape! 

[Dick Bee]

Update on mine; it went out on first attempt, and I thought the air inlet was too small. I lifted it onto two 3/4 inch(ish) slats to allow air through. Only half filled the tube as suggested. It smoked nice and cool for 5 1/2 hrs! No melted cheese. I should add I took the cheese out after 2 1/2 hrs, but let it burn to see how long it would go.

[Craig1975]

I'm just setting up a garden incinerator same as you both have done how many holes in total did you blank off please and unsure how many to leave to allow air to draw through any help is much appreciated please 

[Wade]

Hi Craig

You only need to leave a few holes at the bottom to allow air and sufficient holes in the body to allow for canes to be inserted to support the food racks. Air will then come in at the bottom to fuel the smoke generator, pass over the food and then out through the lid flue. The smoke generator will need little air so providing you have 3 or 4 holes at the same level or below it will be fine.