Wade Posted August 30, 2018 Share Posted August 30, 2018 When you are cold smoking it is important to ensure that there is a good flow of air and smoke passing through the smoking chamber and over the food. In traditional smokeries this was/is achieved by placing the food inside a chimney and letting heat convection and the natural chimney draw maintain a good air flow. In modern smokeries this is achieved through the use of fans. Using a fan on your smoker at home also makes it practical to locate your smoker in a protected shed or garage environment and have the smoke extracted to the outside. Why is it important to ensure that the air keeps moving through the smoking chamber? It helps to prevent the build-up of the heavier smoke tars on the food. The increased air flow helps with the removal of water from the food. This is important when making traditional smoked salmon in conjunction with smoking at temperatures of between 20-24 C. If the cold smoke generator finishes unexpectedly it ensures that air continues to flow through the smoking chamber preventing the build-up of condensation on the food and on the inside of the chamber walls - which can then drip onto the food. The build up of moisture is the main cause of some home smoked foods developing a "musty" smell and taste. The flow of air also helps to ensure that the cold smoke generator continues to burn - especially when smoking in the winter and the nights are cooler. This is a balance though as too great a flow of air can result in the smoke generator flaring up and burning with a flame rather than smouldering. Why place the fan in the flue? By placing the fan above the large buffering volume of the smoking chamber it helps to maintain a gentle, steadier air flow through the smoker and prevents "gusting" across the cold smoke generator - which can result in it flaring up. In many multi-purpose smokers it is also often easier to attach a fan to the top of the unit than it would be to attach it to the bottom. Placing the fan in the flue does have the disadvantage that the exhaust tars do pass through the blades of the fan and over time will deposit there. Although it is reasonably easy to clean the fan blades after each use when used infrequently, if the smoker is in constant use the tars do build up and eventually the fan will fail. In my commercial smoker I leave the flue fan running permanently 24x7 and expect to replace the fan every 6 months. With the low cost of the fans (~ £10 each) this rate of replacement is an acceptable running cost of the smoker. For low volume smokers you would expect the life of the fan to be several years. Which type of fan? It is important that the air is kept flowing, however it needs to be a gentle flow and so the use of a low speed fan is very important. This makes a variable speed large diameter computer case cooling fan ideal. They are readily available, are inexpensive and have standard fittings so are interchangeable. When first setting up my cold smoker i used a fully variable speed fan - the Silverstone FM121 however these are now no longer available in the UK. In the photos below you will see this fan being used. I have now moved to the Antec TrueQuiet 120, however most 120 mm fans that can be set to a fan speed of ~600 rpm would be fine. An advantage of moving to the Antec fan was that the wiring was much simpler - just the + and - 12v DC power leads. The fan speed is controlled through a simple built in switch on the fan. Almost any 12 volt power supply can be used - I use a charger from an old discarded laptop. Mounting the fan In order to make the best use of readily available DIY components for the air management, the fan is easily mounted using standard 100 mm air ducting components. The fan module is made by adapting a Manrose ducting connector (available from B&Q) With a sharp craft knife simply remove the "flat" adaptor side of the connector and then remove the plastic from the round opening. Drill holes for fixing bolts in each corner of flat plate in line with the mounting holes on the fan. Repeat with a second adaptor and sandwich the fan between the two plates to make a fan "module". This can then be inserted in-line using any standard 100 mm off-the-shelf ducting components. ** Note the complex wiring on this Silverstone fan. With the newer Antec fan you only have the two power leads. In my smokery I have the smoke ducting to the outside If you do not need to duct the smoke away from the smoker you can simply slot the fan "module" directly into a 100 mm round hole cut into the top of your smoker. The fan can also be used with Kettle and Bullet smokers without needing to make any modifications to the smoker. Here the secret is Blu Tac - used to keep the fan in place over the top air vent. In order to maximise the life of your fan it is also a good idea to seal the cables leading to the fan motor with a little silicone sealant before the fan is bolted into the "module". Standard kitchen/bathroom sealant is fine for this. 1 Quote Link to comment Share on other sites More sharing options...
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