Kind of long winded but here's how I built my fridge smoker.
Building an Offset Fridge Conversion Smoker
I’ve always liked the efficiency of a vertical smoker and everybody knows that an old refrigerator makes a great smoker. The benefits I see using this type of conversion are low cost to the building (Hah!), less operating costs due to the fridges insulation, the ability to cold smoke as well as hot smoke and the over all fact that you get to build it yourself.
Built properly, a fridge conversion will use less charcoal, produce an even heat and in turn put out some fine BBQ as well as cold smoke bacon, cheese and fish and anything else your heart desires. You name it, it’ll smoke it. For those who are on a budget and looking for that perfect wood or charcoal smoker, something like this will work out great because most of the material you’ll find laying around your favorite scrap yard.
From top to bottom, this unit can be built from scrap (although this one wasn’t) If you choose to, just peruse your local scrap yard rather than use the items like mine that were store purchased. I’m more of the lazy porch swing sitting, BBQ eating type that would rather go to the local hardware than search the scrap yards so this is what I came up with. In fact, I wonder how I worked up the energy to build this thing being so lazy. Well, enough about me.
The first thing you’ll need for this project is an old fridge. The best donors are usually the pull handle porcelain enamel coated models although older magnetic strip seal models will work for you also just so long as there is no foam inside. There’s just a little more work involved.
For the purposes of this tutorial I’ll be using the older style, (a Frigidaire) as this is what I had searched out to use for my conversion.
Gutting out the fridge
Next, you’ll want to remove the freezer compartment, refrigerant lines and any plastic such as shelf brackets, dial or grommets for wiring from the inside of the refrigerator compartment. Be sure to replace all the screws you remove from the brackets and fridge interior as best you can as this will seal the holes that would have been left otherwise.
The model I am using had a plastic panel on the interior of the door.
I’ll remove it and save it as a template and replace the material with 18ga. Sheet metal. Also made of plastic was some inside trim. As this is an integral part of the structure I’ll be replacing the trim as well using the old material as a template in the same fashion. The door seal material will also be replaced. (more on this later)
Now that freezer compartment and all of the shelves have been removed, as well as the thermostat, related dials and stubs of plastic that served as shelf brackets, this is what we have; a pretty empty fridge that will soon be a kick ass smoker.
Before going too much further, I would suggest (if your door panel was plastic like this one) securing the insulation while waiting for the sheet metal to be cut and installed. A simple piece of wire tied across the door in a diagonal fashion will suffice here. You may install your sheet metal right away if you like, however, in my case I ordered the cut sheet metal and continued on with my fabrication. If you move the unit around too much prior to the door skin’s installation this will help to hold the insulation in place retaining its integrity until it’s covered properly.
Receiving my sheet metal I got started on putting in the surrounding trim and installing the inner door skin. To achieve an easy installation I laid out the sheet metal using the old door’s interior marking out the hole for the door latch and then installing the door skin by using the reference marks previously made prior to removing the old plastic interior. I used ½” tech screws to mount to interior sheet metal panel. You may find it easiest to go one corner at a time first the top, then bottom corners being sure that the door continues to shut evenly as you go. Misalignment will make the door difficult to close. Here is the completed interior panel and trim.
Shelving
Next, we’ll need to consider some shelving for this unit. To make things simple as possible I opted to add four racks supported by some angle iron brackets. You can also use stainless steel if you prefer but the cost will be greater. There is enough steel built into the fridge already so I didn’t see the need to go with stainless.
First I measured and cut the brackets. In deciding how many brackets I would place in the smoker. I laid out a semblance of what would be my shelving inside of the fridge with a sharpy marker. (don’t worry, in case you make an error in marking, the marker wipes right off of the ceramic enamel) This gave me an idea of how everything would fall into place and what I would anticipate as far as cutting new holes, patching old ones and where screws might become a problem.
Here are the brackets after they’re installation. I secured the top shelf with a few extra screws as I will be also using a hanger for bacon & such on this shelf and figure for more weight. Overall four screws seemed to hold nicely on each of the lower angle brackets.
Notice the patch where the old thermostat dial used to be, also the hole in the back of the unit where the light was. I used a 500 degree RTV silicone sealant to seal out all of the holes that remained in the unit’s interior with exception of the thermostat dial. There a simple sheet metal patch did nicely. Also notice that enough room was left at the bottom to accommodate what will be a baffle to distribute the heat more efficiently. (more on that as we progress)
The Firebox
Through information I have from various sources, the size of a firebox should be approximately 30% of the size of the smoker. Due to the fact that I’m a lazy BBQ eatin porch swing sitting individual, I’ve opted to use Charbroils “Texas Style Fire Box” for my conversion. First, this assembly sells at most of your home centers for around $50. Secondly, I think that with the price of metal these days, along with the cost of labor. (seein as I’m too lazy to build it myself) will end up costing a great deal more than the store bought firebox) You can build one yourself but since I didn’t, I have no plans for one.
Another consideration is to just use a hot plate. Due to the fact that this is a Charcoal smoker not an electric or propane woodchip burning oven, so, we just won’t go there.
To install this firebox, I made several reference marks from the inside (smoke chamber) dimension to the outside of the fridge (outer shell) so that I would be able to get my firebox relatively centered in the smoke chamber as well as how high I wanted it to sit off of the floor of the chamber. Next, I laid the fridge on its side and set the firebox so that the bolt holes were within my reference points to be sure everything would fit nicely. When laying out you cuts, be sure to center the cutout on the inner shell rather than the outer shell.
After scribing all of my cut lines, I stood the fridge back up and double checked all the markings from outside to inside to be sure everything would line up ok.
NOTE: before making my cuts. I drilled a hole dead center of my cut out to give me the ability to transfer the cut pattern to the inside of the smoke chamber. I also used this as a starting point for my inside cut. It would be a good idea to create a template from an old piece of ¼” plywood or paneling of the cut out on the firebox to transfer the pattern to the inner shell. This will make matching the inside and outside cutouts much easier. I had an old damper plug left over from a “chargriller”. This is what I used for this build instead.
Being assured all was good, I started making my cuts.
Once completing the cuts necessary to make the outer shell cut out, I removed any excess insulation.
After completing the cut out of the outer shell, the pre-marked holes were drilled and the firebox checked for a proper fit. With the fit up of the firebox complete a small amount of the 500 degree rated RTV sealant was applied to the perimeter of the cutout and the firebox bolted into place.
Going back to the inside of the fridge and placing my previously noted template into the predrilled hole, you can see how this will greatly aid in making the cutout to the inside shell. Just scribe the necessary lines around the templates perimeter and you have your inner draft plug ready for cutting.
Now the inner shell can be cut easily matching the previously made cutout on the outer shell. You’ll want to be sure to have plenty of jigsaw blades on hand while making cuts on the inner shell because the porcelain enamel is pretty hard and will dull the average metallic blade with just a few cuts.
The Chimney
Moving to top of the unit we’ll lay out the chimney and make our cuts much like the firebox cutouts were made. Be sure to center the chimney on the inner shell rather than the outer shell.
I used typical sheet metal duct for the chimney with an added rain cap cutting my flashing at the bottom for the installation. Plenty of 500 degree rated RTV around the chimney prior to its installation will prevent leakage.
Following the installation of the chimney, be sure to square it up using a combination square before the silicone sealant sets up. Once its square & true to the world leave the whole thing be for a while so that the silicone has a chance to set up.
After the silicone has set up for a while, pre drill and drive in a few screws through the flashing tabs. You don’t need to get carried away with the screws here, 4 were plenty for this installation as it is being caulked with sealant both inside & out.
There you have it. Add the cap and the chimney is now complete.
It has really paid off using an extra long drill bit to make your pilot holes in the center of your cutouts. By drilling a pilot hole first, the transference of the cutout on the inner shell is much easier however its purchases like these that really run up the bill on the build. While money doesn’t grow on trees, neither do refrigerators. I think that the longer drill bit was a necessity on this project and I’ll have it for another project on another day.
The Test Run
With everything pretty much complete it’s time to test this smoker out and see how she runs. With a little coal in the firebox she climbs up nicely to 130 degrees.
all went well with is for a while so I figured lets ramp it up a bit and on went more coals.
up goes the temp to 240* and then up further to 270* and continued to climb to near 300*.
Being happy with how high the temps were I let things settle back down and added a second probe monitoring the temp ranges to 230*. I found a top temp of around 230* to 240* at the top rack height while the bottom rack registered a temp at 194*, with a 46* difference between the two areas. However, at lower temps, say 130ish, the temp difference is much less with the balancing range at about 110* with a 7 to 10 degree difference. I’m hoping the baffle design I’m considering will alleviate this problem.
Overall I'm happy with the way it ran at it's lower temps with a good response to the damper and a nice steady 170ish roll with no fluctuation. Next I'll see what the lowest manageable temp I can achieve and see how that holds. I'm looking forward to cooking some dead animals in this thing real soon.
Installing the Baffle
My baffle material was 9ga. 16” tapered tube used for the fabrication of traffic poles. While you may not find a source for this material readily available, The use of 1/8” steel plate bent to an adequate diameter to resemble the baffle below will work out nicely.
Using the tiles I was able to achieve a regulated temperature by raising or lowering my baffle until the top and bottom temperatures were even within a few degrees. I added a couple of legs to these one on each end using althread so that in the future I could make further adjustment if necessary.
Alrighty,,, Lets Eat!!!
Posted: Sat Sep 12, 2009 11:17 am