Ferm Chamber

I built a ferm chamber based around a bar fridge. I built an insulated box around it with the door removed. The inside is lined with reflective foam insulation, all joints are sealed then the whole chamber is wrapped in r30 pink bat and cladded in board. I keep the thermostat turned to max and have it wired into a dual stage temp controller, which powers the fridge to cool down the chamber for cooling and powers a fremwrap heater for warming.

The first brew, which was an ale, I had a lot of trouble keeping the temp below 70F. I added a fan to the front of the fridge to circulate air, but that only made it worse. The back of the fridge is left open, so it is not due to heat from the compressor. I live in Canada (Edmonton), so I am not dealing with extreme temperatures. My next brew is going to be a lager, so i NEED to get this fixed.

Should I bypass the thermostat? I have a small deep freeze, and am considering trying to remove the coil and compressor from that so I get more cooling (but I have no idea how).

looking for ideas here

 

The first thing that comes to mind is that your fridge is under sized to handle to volume of your chamber. Try dividing the chamber in half with a piece of foam to see if the fridge can handle half the space. I have the same basic build with less insulation in a warmer climate and can get to it down to 50. I used a Danby Model# DCR88WDD its got the freezer on top. I am assuming that the with the freezer it can output more and lower temps than a fridge only unit. Sorry its all I got. Hope you get it fixed.