How to Turn an Old Fridge into a Cold Smoker
Cold smoking is cooler in a fridge!!
There are plenty of times when one has an old fridge sitting around waiting for disposal. I had a tall old fridge that I earmarked for turning into a smoker from the day it stopped working but due to time being at a premium recently it just sat around looking more and more unhappy with its life as an ex-fridge. I have finally had enough spare time to start work on converting from fridge to cold smoker and it just so happens to coincide with me beginning to use HubPages.
This article is a look at what was done and is intended to provide inspiration to those looking to begin (or continue) cold smoking food. Due to the nature of the project I decided that it would be best to try to work to as low a budget as possible to keep the cost of the build well below that of models that are purpose built and on the market. Secondly I wanted to keep the complexity and tool requirements as low as possible so that anyone who likes smokey deliciousness and has an old fridge handy can turn their hand to greatness.
What is Cold Smoking??
Cold smoking is more of a curing process than a cooking process (whereas hot smoking is a cooking process). Smoking has both anti oxidizing and anti microbial benefits as well as adding that smokey flavour we love so well. Cold smoking normally occurs over a long period of time (for me 12 hours is the minimum and some people will smoke some foods for a week or more very gradually) in temperatures that remain low for the duration of the process. The normal temperature range for cold smoking tends to be 10 - 32 Celsius (50 - 90 Fahrenheit). It is recommended that you never cold smoke at temperatures above this range as the food may spoil due to the onset of bacterial growth in the warmer temperatures. There are some products such as cheese that can be popped into your smoker with very little preparatory work but many need to be cured before they should be smoked. There are a variety of curing methods including dry curing (great for meats) or brining (soaking in salt water). There is a wealth of knowledge available on curing methods and what to use where and I suggest reading as much as you can before trying that expensive bit of salmon you are longing to get smoking. I will try to write a hub on curing processes in the future when I have some time. I would always recommend using the best quality meats and fish that you can afford as well sourced fresh produce will be safer to smoke as well as taste a lot better. Done correctly, and in combination with curing processes, cold smoking can dramatically increase shelf life of a product allowing it to keep for many weeks and still taste fantastic. I would recommend starting with inexpensive easy to smoke items such as cheeses until you have got your method down and know the ins and outs of your smoker.
IMPORTANT SAFETY INFORMATION: - Do not cold smoke at temperatures exceeding 32 Celsius (90 Fahrenheit)
- Use exemplary hygiene methods during all preparation and smoking stages to minimize risk.
- Refrigerate anything that you smoke
Picture Credit: Picture taken from www.grillingwithrich.com (note: this is a different Richard and I do not own any of the content on his site).
Really? An old Fridge?
Yes really, a fridge is in fact perfect for turning into smoke cabinet for use with a cold smoker. Fridges are large spaces that are sealed and perfect for holding smoke, they tend to be well insulated to keep internal temperatures constant and perhaps best of all they are really easy to come by.
NB. Most fridges are lined with plastic and are not suitable for hot smoking where temperatures are much higher. Do not attempt hot smoking in your fridge!
IMPORTANT SAFETY INFORMATION!!
Fridges are able to maintain their low temperatures by pumping refrigerants through a heat exchanger. There are a few types of refrigerant but it is inadvisable to cut any pipes or try to remove any of the heat pumps or heat exchange tubing from the back of the fridge. A cold smoker will not reach temperatures that risk the refrigerant leaking out so it is best to leave it all well alone. If you do accidentally damage the pipes and refrigerant begins to leak out, make sure the fridge is in as well a ventilated area as possible (if inside open windows and leave the room) and do not breath any fumes. Refrigerants can be bad for both you and the environment and should be treated carefully.
A lot of useful information regarding refrigerant can be found here: http://webarchive.nationalarchives.gov.uk/20140714084352/http://www.hpa.org.uk/ProductsServices/ChemicalsPoisons/ChemicalRiskAssessment/ChemicalIncidentManagement/RefrigerantIncidents/GeneralInformation/
Fridge to Smoke Cabinet
This section will detail the steps I used to convert my fridge. It is unlikely that you will have the same model of fridge but all the principals apply to any fridge type. I have tried to keep the budget to a minimum but you can be as frugal or as lavish as you wish.
A rough outline of the next few steps is as follows:
1. Clean Fridge (don't forget the inside of the door like I did first time round).
2. Decide intervals for shelving/ hanging.
3. Cut and fit slats to allow fitting of removable metal rods.
4. Cut metal rods to size in desired quantity.
5. Fit chimney.
6. Apply sealant to any gaps or holes.
7. Fireproof bottom of fridge for use with smoke generator.
8. Install thermometer(s) to allow monitoring of internal temperature
9. Last clean and smoke test
- Sponge and Bowl
- Drill (cordless is ideal)
- 6 mm drill bit for metal
- 6 mm drill bit for wood
- Stanley Knife (or similar)
- Sealant gun
- Bench Vice
- Coping saw
- Steel rule
- Measuring tape
- Center punch or robust nail
- 15 mm circular cutter
- Hacksaw (12 inch with metal cutting blade)
- File for metal
- Tin snips (metal shears)
Time required: ~ 10 hours
- Old Fridge
- Wooden slats (I used a few old bed slats)
- 6 mm Bolts (long enough to go through fridge wall and slats)
- Nuts and washers to fit bolts)
- 1-2 feet of Steel Pipe 30 mm diameter (~ 1.5 inch)
- Haemerite Paint
- Silicone Sealant
- Iron/steel rods at least the width of the inside diameter of your fridge (I cut mine from an Iron gate)
- BBQ / Smoking Thermometer (long stem ~5 inch)
- Wine corks (2 per thermometer)
- Steel sheet for fireproofing bottom (optional depending on smoke generation type)
1. Clean up your fridge in preparation to begin work. The fridge I used had been outside for some time and had gone a bit... well... green on the outside and had some snail lodgers on the inside. I turfed out my unwanted guests and set to work with warm soapy water and a hosepipe and in no time my fridge was good as new. Let your fridge dry before moving on.
2. Making Internal Racking
My aim was to create a smoke cabinet that can be used for a variety of smoking applications including hanging large joints centrally from meat hooks or for fish or cheese on horizontal racking.
First measure the internal dimensions of your fridge and have a think about where you would like shelves. The next few steps will detail how to achieve the design shown in the picture of this step.
3. Once you have decided how many shelves you would like and how much hanging space it is time to work on the slats. Start with the central slat (which will be the longest of the 3) and draw horizontal lines (with a steel rule or setsquare) where you want the base of each notch to be (this way you ensure level racks).
Once you have marked all the rack heights measure the intervals between them and mark off these same intervals on the shorter slats. Note: for me the central slat has an additional top notch that does not align with the shorter slat notches; this is a notch for a single bar for hanging only.
Once you have each slat marked out you can cut the notches (see picture ). I used a coping saw while holding the slats in a bench vice. Make sure that the notch is a little larger (though not too much larger) than the width of the metal rods that you will be using so that they are a snug fit.
4. To attach the slats you will need to lay hands on a drill (cordless is ideal) as well a drill bit for wood and a drill bit for metal of the same size (I used 6 mm). I placed the central slat first into the position that I required and after making sure that the slat was perpendicular to the fridge (vertical) I marked the locations to be drilled using a center punch and a small hammer.
I then drilled the marked holes with the relevant drill bits (metal for metal and wood for wood) and attached the slats using 6 x 80 mm coach bolts with the head inside the fridge and the nut on the outside.
In the picture you can see that the bottoms of the notches are vertically aligned so that the shelves are level. Make sure to get both sides lined up before you attach anything too securely.
5. Using a hacksaw (or angle grinder with a metal cutting disc), cut the metal rods to a length approximately 10-15 mm shorter than the internal width of your fridge. File the ends to round off the edges and to remove any burs or sharp bits. I cut 8 rods, 3 sets of 2 for horizontal shelves/racks and 2 (slightly thicker) for central hanging.IMPORTANT: Please wear adequate safety protection as metal filings in your hands or eyes are decidedly NOT FUN!
6. At this point you should have something that is beginning to resemble a smoke cabinet. It is time to fit a chimney so that smoke can slowly escape so that it does not get stale in there. The chimney should not be too large though or there will be too much of an air exchange.
I found a suitable piece of pipe that was mild steel and had been part of a shower rack that was no longer in existence. I cut a section of pipe about 1 and a half feet long, sanded the rust off, cleaned it and then painted it with black Hammerite (a paint for metal).
There are several ways to cut a hole in metal and if you have a circular cutter of the correct dimensions for your pipe then that would be idea. I did not have the right tool for cutting a circular hole in metal so I opted for a much cruder method of repeatedly piercing holes in the metal with a nail in a circle of the desired diameter. Be careful of sharp edges if you do this.
7. Making an aligning hole beneath the first hole may be tricky but it depends on the lining of your fridge. I removed some of the insulation uncovered by the first hole and the forced my soon-to-be chimney down until it was pressed against the inner liner of the fridge (twisting helps with this).
8. Fit your chimney so that it protrudes a little way into the inside of the fridge (2-4 mm would be fine) leaving enough pipe to be able to put sealant round later.
You may need to apply a second coat of paint if you scratched it during fitting as the paint will protect your chimney from rust making it last longer.
9. Use a sealant gun to add silicone sealant to around the holes that you cut (top and bottom) to prevent unwanted leaking and to ensure that no unwanted creepy crawlies get in between uses.
10. Your smoke cabinet is almost done. Depending on the construction of your fridge and how you are planning on generating smoke it may be necessary to fireproof the bottom portion of your fridge even though most smoke generators don't produce much heat. For me this involved lining the bottom of the fridge with some sheet steel and the inclusion of a raised rack to dissipate any heat. Sadly I don't have any pictures of this step as my camera battery died.
11. Cold smoking must occur within a reasonable temperature range of ~10-32 degrees Celsius (50 - 90 degrees Fahrenheit) so it is strongly recommended that you install at least one thermometer into your smoke cabinet. There are several types available but I opted for two long stem thermometers one just above the smoke generator box portion and one slightly above center of the racked section where food would be. There are many thermometer options even remote ones that you can carry back to the house with you and monitor your smoker temperature in comfort! I have included a list of recommended thermometers including the two that I bought which I am very pleased with (see Thermometer section).When installing your thermometer probe make sure that it is well insulated from the casing of the fridge so that you get and accurate reading from the inside rather than the case temperature. I achieved this by lining the hole with cork (from wine corks). After drilling the holes with a 15 mm circular cutter I drilled a small hole into the wine corks that would allow me to pass my thermometer probe through and then with a sharp knife I trimmed the cork sides so that they would fit snugly into the hole. I used 2 corks per hole that were about 3/4 of their original length with about 5 of protuberance on either side so that the thermometer back was not touching the fridge door.
12. Clean all of your racking and double check the cleanliness of your smoke cabinet and allow and sealant and paint that is wet to dry at least overnight. Once all paint and sealant is dry you can fire up your new smoker and give it a try. I would strongly recommend reading around the subject of cold smoking before you try anything as if done incorrectly cold smoking could lead to you culturing some nasty bacteria by mistake and this is far from desirable. Take time and care with your hygiene and product sourcing and make sure your temperatures do not rise too high inside your smoker and you should be golden. Good luck, be safe and have fun.
I used 2 of these to go through my fridge door and they are preforming perfectly, good construction and year warranty is an added bonus
As discussed before it is important to keep your smoker within a specific temperature range to avoid bacterial growth on the food you are trying to cure. Here are several thermometers that are suitable for a fridge build the main criteria for which is a long enough stem to penetrate through the fridge casing and into the smoke box. I used 2 thermometers but you can use more if you wish (though more than 3 may be overkill (top middle and bottom)).
So you now have a completed smoke cabinet and are eager to get some food smoking. There are several ways of making smoke and the type of smoke that you make will affect the flavour of the item that you are smoking.
It is possible to make your own smoke generator though it is something that I have not tried so far (I feel another lens coming on in the future) but there may be some information lurking out there on the internet. Several of my friends are into smoking and I bought a pre-made smoke generator that is simple and low budget (see next section). I have listed a few of the products that I or my friends have used or that have come well reviewed below and hope it is of use.
Pre-made smoke makers
Here are a list of recommended smoke makers. If you are to go down the route of buying one then it is important to take into account the dimensions of your smoke cabinet before you buy as a fridge with a door that wont close is no good to anyone. There are a fair few smoke generators out there on the market but I have picked three that to me seem to be the best options. Two I have personal experience with (a-maze-n pellet smoker I own and the Bradley smoke generator I have witnessed in action through a friend of mine) and one I don't know so well but comes with great reviews.
Simple and cost effective. Wood chips are packed in and due to the maze like arrangement of the mesh only a little can burn at a time resulting in smoke for a long period of time. I have used this product and it is great for those starting out.
Wood chips - What to burn and Why
The choice of wood chips burned in your smoke generator will affect the taste of your food as each wood has a slightly different aroma and flavour when burned. There are many popular smoking woods but perhaps my two favorite are apple and oak. Apple is a great all rounder with a slightly softer, fruity flavour and oak is a slightly stronger, almost nutty flavour which I love, especially for salmon.
Generally speaking you wont go too far wrong when using wood chips from fruit trees: commonly, apple, cherry, lemon, fig, apricot, orange and plum.
There are also several non-fruit tree woods that are widely used and available: Oak, hickory, maple, ash, mesquite, beach and olive as well as other more obscure woods such as sassafras, acacia and persimmon.
Below I have located some of my favorite woods from a brand that I have used before. It should be noted that there are many many types of wood out there and experimenting with different woods and brands will all help you achieve a more unique flavour tailored to what you like best.
NB. The wood chips below are for smoke generators that use loose chippings rather than custom formed discs such as the Bradley Smoke Generator. Make sure that the chips will work with what you have before you buy. The chips below are perfect for maze type designs such as the ones recommended above.
You can of course chip your own wood if you have a good supply but there are two things to bear in mind.
1. NEVER use wood that has been treated or painted as the fumes will get into your food and at the very least make it taste bad and possibly harm you too.
2. For best results when using your own wood you must season it so that it is very dry and once chipped store the chippings in a low humidity environment. Many commercial chippings are kiln dried to produce the results that the do though I have produced good results with my home made apple and oak chippings after a year of seasoning (minimum).
If you are not sure which wood to go for this is a great way to go. A mix of favorites to cover all bases for smoking.
A great all rounder that I find suitable for any meat type. Has a mild and slightly fruity flavour.
A big favorite of mine. Has a fairly mild and slightly nutty flavour. Lovely with salmon.
A delicate flavour perfect for smoking fish. I have also had good results with beef and pork.
A different wood from the norm, good with poultry, beef and pork. Great for something different.
Do you smoke? (only want to hear about the foody kind :) )
Do you smoke food at home?
I hope this has been a helpful or at least interesting read and would love your feedback and tales of fridge smoker related activity. Happy smoking.