Brewing Hacking

BrewPi: True GDM-6-LD

After having seen a couple of BrewPi builds on the net I just had to build one of my own.

Tear Down:


I purchased this beverage merchandiser second hand from a used restaurant supply store to use as my fermentation chamber. This is the True GDM-6-LD.
The process was extremely easy and doesn’t really warrant step by step instructions. There were maybe ten sheet metal screws in total required to remove the front/back panels and thermostat. I would just advise people to be cautious when separating the thermostat from the interior panel. Also, set the dial to zero on the thermostat before removing it so that when you put it back it corresponds to the correct setting in case you ever want to convert it back to stock.


  • 14 AWG
  • 22 AWG Two Wire Cord
  • 6″ Right angle Micro USB to USB A
  • 10′ Micro USB to USB A
  • 5v 2A USB Power Supply
  • 14 & 22 AWG Ring Terminals (Red and Blue)
  • 3 Port Push-in Wire Connector (1)
  • 2 Port Solderless Splice Connector (1)
  • 1/4″ Grommet
  • Permagum (Duct Sealing Compound)
  • 25A SSR (2)
  • 3 Pole Circular Connector M & F (2)
  • 1/2″ Split Loom Tubing
  • Cable Management Kit
  • Black Spray Paint
  • RJ-11 Connector
  • Heat Shrink Tubing (various sizes)
  • Electrical Tape

The build was fairly easy and straight forward to my surprise. I didn’t run into any problems during the build and really didn’t do anything vastly different from the fridge hacking guide for compressor control. I did get lucky in that the neutral terminal block on the fridge had one opening which I used to connect the heat cable neutral to. Also, I didn’t use heat sinks on my SSR’s because mine came with thick aluminum plate to absorb heat. I mounted them to the back panel of the fridge using thermal tape to use the whole grill as a big heat sink. So far the panel has been cool to the touch. The other thing I did was install a rubber grommet into a hole I drilled in the sheet metal interior panel for the heat cable to pass through. I did this to prevent the sharp metal from cutting the silicone covered heat cable. The permagum was used to reseal the cable port in the fridge used to pass wires through to the back panel after I was done routing the new cables. The finishing touches included routing the cables through a cable management kit I cut to size and spray painted matte black. I then just cut several short pieces of split loom tubing to organize the cables further.
I have used the system now for several brews and it has reliably worked very well. I have zero complaints. I will post more detailed information on fermentation profiles for the BrewPi in the next brew day post.