Wiring a Ranco ETC to to a True GDM

[Newbie]

I have a True GDM (glass door merchandiser) model GDM-26 PE57161.

I want to wire a Ranco ETC so I can use it for a fermentation chamber.

The volts measured at the compressor adjustment knob are around 220V.

I was planning on having the fan run 24/7 and the compressor come on when it needs to cool the box.

Any help how to do this would be great.

Thanks!

[ajdelange]

The fact that the compressor control exhibits voltage around 220 tells me 2 things.

First - that the unit you have is a 220V unit (I think most of these are 120)
Second - you need to get someone involved who understands refrigeration systems.

Without knowing anything more than that the unit is 220 it is impossible to make any firm recommendation beyond simply setting the unit thermostat to the lowest possible temperature and plugging it into the external controller.

Why do you want to run the fan continuously?

What temperature range do you anticipate working at? The reason for this question is that if you are contemplating using it at typical ale or even lager temperatures you will be operating it well outside its design range (33 - 38 °F) and this is not typically good for refrigeration equipment. Apparently these things do not have a TXV and so one might worry about short cycling and early compressor burnout. If you do try this be sure to set a large differential on the external controller or install some sort of delay in the compressor circuit. An experienced technician with the ladder diagram in front of him could doubless come up with something but this is why you need an experienced tech.

[Newbie]

The unit says 110v on the sticker inside so I am guessing there is a transformer?

[ajdelange]

That's a possibility but I suppose you might see 220 V if you measure between the hot side of the run and start windings with the run winding energized and the start winding open due to auto transformer action. The point is that you need to know - not hypothesize. Is there a wiring diagram?