The keg dispenser is a Tappan chest freezer. I removed the lid of the chest freezer and mounted a wood "collar" on top. The lid was remounted on the collar. The primary motivation for making the collar was to be able to pass shanks through to the inside without having to worry about coolant lines. Six beer faucets attach to shanks which pass through the collar on one side of the chest freezer. The height of the collar was chosen to allow a five gallon glass carboy with an airlock to sit on the compressor motor "step" within the chest freezer.
The chest freezer holds eight five gallon kegs with room for a five pound CO2 cylinder and five gallon carboy. I use a three regulator assembly from Superior Products. This assembly allows for one pressure line to service multiple kegs. The air cock of each regulator is attached to a four-way air distributor. This allows up to four kegs to be dispensed at each of three different pressures. I typically adjust one regulator to a lower pressure for dispensing lighter beers, a second regulator to a slightly higher pressure for dispensing darker beers and a third regulator at a high pressure for carbonating newly kegged beers.
The major drawback of the chest freezer is that it doesn't have a bottom drain. A significant amount of condensation forms on the inside walls of the chest freezer and eventually ends up in a puddle on the floor. I have to remove all of the kegs once every few months and mop the water from the bottom of the freezer. I don't believe the condensation is unique to this chest freezer. I believe that it is simply a result of operating the freezer above freezing temperatures.
There's one major flaw in the design of the collar. The plastic insert of the freezer lid tapers away from the edge, however, the top of the collar is flat. I have had to almost completely release the pressure of the lid hinges in order to allow the lid to lie flat on the collar. Consequently, I have to prop the lid open when accessing the inside of the freezer. I should have tapered the collar to match the taper of lid. I could remove the plastic insert. In hindsight, I wouldn't go to the trouble of making a collar again. I would simply mount a pedestal tower through the lid of the freezer.
The temperature of the keg dispenser is controlled by a William's Brewing Controller ($50).
"The Controller operates by sensing the pressure of a gas-filled sensing probe via the 6' capillary tube, which turns a mechanical relay on and off. No electric power is used in operating the Controller. The only power consumed is the power used by the refrigerator or freezer to maintain your set temperature."
"The Controller features a 3 ½º differential."
I think the William's Brewing controller functions as advertised and is worth the $50 price tag. However, in comparing it with the more (almost twice as) expensive Brewer's Resource Ferm Temp, I think the capillary tube and "bulb" sensing probe are a major disadvantage. And while the capillary tube " can bend around a refrigerator or freezer door ", it must be treated with far more care than the wired solid-state sensing probe of the Ferm Temp. And of course, the Ferm Temp offers the added advantage of controlling both a cooling and heating source (which you wouldn't need for a keg dispenser unless the outside air temperature dropped below the dispensing temperature).