The Cottage Smallholder


stumbling self sufficiency in a small space

Guest spot: how to build a home cold smoke room and a smoke generator by Smoking Methusala

view of Smoking Methusala's garden and Welsh hillsHere is the second part of Smoking Methusala’s post. Here he gets down to the nitty gritty.

Smoking Methusala’s cold smoker journey. Part two.

Here are the instructions for creating both the home built smoke room and the smoke generator.

Making the smoke room:

The fridge part is easy. Assuming you have a larder fridge with no freezer box in it and the cooling element is a panel at the back of the fridge.

Remove any internal bits like the on off switch, light and leave the gas parts in place as they will cause no problem left in situ but will cause a problem if you start cutting through pipes and releasing refrigerant gas into the atmosphere.

Cut a 3 inch diameter hole in the top of the fridge to insert a suitable length
of pipe to act as a chimney. You can use a hole cutter or use a jig saw after drilling a pilot hole to insert the blade.

Since we are cold smoking, the chimney can be anything from a length of guttering downpipe to a plastic pipe that will fit snugly into the hole. Seal it with a proprietary silicon sealant. The length of the chimney is not critical but should extend high enough so that any passing person of normal height will not get a face full of smoke :)

Now drill another hole the same size in one of the sides or even the door as low down the fridge as is reasonably possible. This is to allow through draught to the smoke room. Arrange a means of cutting off this flow through the second hole. Such as simple as a plastic flap attached by a screw at the top which will allow it to be opened a little at a time (like a cell door peephole) as required when the smoke room is in operation.

When we built our smoke room we canted the chimney 3 degrees from the vertical to aid the aero-dynamic flow through the smoke room to assist in the swirling effect of the smoke. My wife looked at it and after listening to our technical explanation declared,
“Ah! So you welded it up crooked ”
Sigh, don’t you just hate it when that happens. We like to think it gives the smoke room character :)

It goes without saying that this arrangement can only be used outside and there should be no attempt to operate the smoke room indoors or in a confined space.

Making the smoke generator:

The smoke generator does require a level of engineering expertise or a friendly mechanic with a workshop.

We used an old piston from a 50cc engine.

Drive out the gudgeon pin if its not already missing and cut the top off the piston. You now have a tube with a hole in each side. Remove the internal shoulders as flush as possible, where the gudgeon pin used to be and plug up one of the holes in the side. You now have a tube with one hole in the side.

Find a suitable piece of tube, metal not plastic, about 8 inches long that fits snugly into one end of the piston. This will be the fuel hopper so make a removable lid for the top end.

This fuel hopper should descend inside the piston to a level of 1 inch above the top edge of the hole in the side. Drill the hopper and insert a pop rivet as a stop so that you will always be able to put it in the correct position again each time it is removed.

Now make a removable cap for the bottom of the piston out of any metal and drill a hole through the centre of it. Braze or weld a small piece of brake pipe into this hole. This will be the air inlet to the fire which will have a plastic tube attached from a tropical fish tank pump.

All that remains now is to insert into the piston a small piece of metal mesh to act as a fire grate so that it rests just under the lower edge of the hole in the piston side. Just make it a tight fit as the weight of the fire is negligible.

Insert a short metal tube into the hole in the side of the piston (tight fit) – this will be where your smoke will come out.

Make a metal plate to screw to the outside of your smoke room as low down as possible and drill a hole right through into the smoke room in the centre of the plate, This should be the same size as the metal smoke tube. The metal plate acts as a hanging point for your generator and also isolate the heat created by the generator from the side of your smoke room. Your smoke generator will rest on the plate with its smoke tube poking into the smoke room.

How to operate the smoke generator:

To start the system up, fill the hopper with your wood shavings/sawdust mix and in the end that’s going to be inside the piston crumple up a couple of tissues to hold the shavings in place when inserting the hopper.

Use half a charcoal briquette and get it glowing with a blow torch and then drop the charcoal into the piston on to the fire grate. Insert the fuel hopper and switch on your tropical fish pump. Smoke will start filling your smoke room and after a few minutes the paper plug in the base of the hopper will burn away and the wood shaving will drop (you will hear them) on to the fire. 10 minutes later the charcoal will have burned away and you’ll be generating smoke using whatever flavour shavings you loaded your hopper with.

Adjust air flow from the pump to the fire and air flow through the smoke room using the lower vent. Practice will be needed to get the system running smoothly.

Too much air from the pump will generate too much smoke, and waste your wood fuel. Remember adjustments can take as long as 15 mins to settle to the new setting so don’t rush. If your pump does not have output control just use a fish tank air flow control valve from any pet shop, they look like a mini plastic vice and just squeeze down on the plastic outlet pipe as required.

The best fuel to fill the hopper with is a mixture of shavings, very small chips and sawdust of the preferred wood type. A complete fill of sawdust has not met with much success.

For those of you that feel the smoke generator is a project that is beyond your available expertise, no problem. On the Internet are at least 2 purpose built smoke generators available that I can recommend. The Smoke Pistol and the Bradley Smoke Generator.

Both work on the same basic principle and each has the advantage of supplying a variety of wood flavours in fuel hoppers designed to fit the respective device. The Smoke Pistol retails at under ?100 and the Bradley smoker at around ?150. Both can be used with the smoke room as described above.

I’d suggest that your first attempts at operating the smoke room should be confined to smoking sausages and cheese which are both easy to do and a lot less expensive both in time and money than a side of pork loin :)

Smoking time is considerably shorter than smoking in the “bacon ladies” chimney and a good guide to timing can be the Bradley smoker recipe book available on the Internet.

N.B. Whether you make your own smoke generator or are buying one of the commercial models please remember they DO get HOT when operating. So make a guard around the generator to keep little fingers away, as well as your own.

Cold smoking tips:

  • Cold smoking requires you to keep the temperature in the smoke room to between 75 and 85 degrees F and can be monitored by a decent fridge thermometer. Smoking in the winter months should never create a problem but in high summer, should we ever have one, the temperature can easily exceed 85 degrees F in the smoke room. What I do is place a couple of baked bean tins nearly full of water in my freezer and when full of ice just put them on the top shelf of the smoke room, replacing as needed, works fine :)
  • I use the existing fridge shelving, removing and replacing as required to allow to hang a joint and have a shelf to place cheese, sausages, bananas, fish etc at the same time.
  • I also use my smoke room also as a drying room. After preparing the joint for smoking I hang it in the smoke room with the bottom flap open wide to assist air flow for an hour and maybe longer if possible. When the joint takes on what looks like a slight shine on the meat it has formed the pellicle. I think this aids the smoking process and fortifies the fridge storage time of the completed joint.

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5 Comments

  1. This is pretty nifty. I love reading posts like this. There is another blog I read that based on living more simply. It has lots of posts about ‘wood gas’, with lots of details. there are even clips of Norwegians who power a car on it. FAB!

  2. By coincidence I commented on another posting here saying I couldn’t get smoked fish and was considering trying to DIY. Then I found your excellent posts.

    I think we could handle making a similar smoke room (or know a man who can). But it’s the outside temperature that’s worrying me now. We have three seasons here: hot, wet hot, and bl**dy hot.

  3. Fiona Nevile

    Hi S.O.L.

    Yes I agree. It’s nifty!

    Hello NotDelia

    You could adapt the baked bean can ice cubes into far larger ones and create an chill house come smoker. You might have problems with condestion though.

    Watch this space. Soon posting how to smoke usuing a small garden chiminera and butcher’s muslin! The U.K. is so resourcefull ;)

  4. Hi,

    I built my smokehouse from plywood, but I had a lot of problem with smoke generating – started with a electric fan and ducting but ended up with a traditional firepit – it does need tending to every 20 min. or so – pretty troublesome. I would love to see some kind of a drawing of generator described above as I have problem to imagine it…

  5. I am in the process of building a smoker and am using a working order double door freezer/fridge with my smoke pipe running through the freezer to cool the smoke down and the fridge part to keep the meat cool. This will allow me to smoke even in the middle of summer.
    Once I have done some smoking , and it is successful I will place a pic on the site
    Dave
    South Africa

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