New Fermentation Chamber: True GDM-26 Refrigerator Cooler

[raouliii]

......I put my energy monitor on it and it's going to cost me nearly $500 / year in electricity to use this fridge (at $0.15/kwh)!!! It's averaging 350 watts / 3 amps over 48 hours of use. I do hear the compressor cycling on and off, but it's running most of the time, I'd say 80%+.....

I'm not completely sure of the calculations you have made. Is this it basically? 350x24 = 8.4KWH/day @$0.15/KWH would result in $459/year ?

The compressor is rated at 115VAC/4.4A which is about 500watts when running and the evaporator fan is rated at 9watts which runs all the time. Therefore, during your monitoring the compressor consumed 340watts on average, so it ran about 68% of the time, 340/500.

The manufacturer claims energy consumption of 2.08KWH per day, or an average of 86watts continuous. This represents about a 17% run time and would be about $115 per year at $0.15/KWH. Of course that figure is best case test results.

Still, I'm not sure why your measurements would be so different from the manufacturers. Either the unit is not operating correctly or an unloaded unit consumes 3-4 times the energy of a perfectly operating/filled unit.

 

[wantonsoup]

I'm not completely sure of the calculations you have made. Is this it basically? 350x24 = 8.4KWH/day @$0.15/KWH would result in $459/year ?

I have a power meter that calculates the cost per year for me. I left it running for more than 48 hours (after it had been on for a few days, too, so it wasn't just some initial startup running or anthing) and that's where I got the numbers.

Still, I'm not sure why your measurements would be so different from the manufacturers. Either the unit is not operating correctly or an unloaded unit consumes 3-4 times the energy of a perfectly operating/filled unit.

I don't think a freezer empty would use more electricity anyhow - more airflow means it should run more efficiently and theoretically cost less.

 

[raouliii]

I have a power meter that calculates the cost per year for me. I left it running for more than 48 hours (after it had been on for a few days, too, so it wasn't just some initial startup running or anthing) and that's where I got the numbers......

But the cooler was empty, correct?

......I don't think a freezer empty would use more electricity anyhow - more airflow means it should run more efficiently and theoretically cost less.

I disagree. A refrigerator or freezer is designed to operate with a load. I don't think it's about airflow, but a measure of the resistance to heat conduction/loss, thermal resistivity might be a way to describe it, of the items in the unit. Air would have very poor thermal resistivity while the solids or liquids being refrigerated have higher thermal resistivity. The items in the unit function as cold sinks that resist the absorption of heat. Once they are at the target temperature, it takes little energy to keep them there. But then again, maybe I'm wrong.

 

[beaksnbeer]

But the cooler was empty, correct?

I disagree. A refrigerator or freezer is designed to operate with a load. I don't think it's about airflow, but a measure of the resistance to heat conduction/loss, thermal resistivity might be a way to describe it, of the items in the unit. Air would have very poor thermal resistivity while the solids or liquids being refrigerated have higher thermal resistivity. The items in the unit function as cold sinks that resist the absorption of heat. Once they are at the target temperature, it takes little energy to keep them there. But then again, maybe I'm wrong.

Yes, they are designed to run WITH a thermal mass factor other wise they lose a lot opening/closing and quite a bit during defrost.

 

[wantonsoup]

Fair enough.

 

[c3hutson]

Bumping this with a link to my thread asking about the hinge mechanism and possibility of building a collar on the GDM 26 true cooler.

https://www.homebrewtalk.com/f11/true-gdm-26-display-cooler-460934/#post5925538

 

[joety]

I removed and bypassed the existing thermostat and wired in a STC-1000 controller mounted in the lower front panel. Using the existing wires, a heater module was installed into the upper area between the evaporator fan and the evaporator core. The thermostat plate was replaced with a duplex receptacle having independent auxilary heat and always ON options.

Hi Raouliii, you've provided the best information I could find so far on True cooler conversions. I am knee deep in a conversion of a model GDM-41. I am using a Love dual output controller which I'll mount close to where you mounted it. I cut the connection between the pink and black wires leading to the compressor outlet and spliced in three new pink wires on one (pink) end and a black wire on the other (black) end. I also spliced in a white/neutral wire for the controller and the neutral wire of an extension cord (to be used to plug in a heater). I made all these connections inside the existing box. The three pink, one black, and one neutral wires all exit the box (along with the neutral end of the cord) and will be connected to the controller along with the hot end of the cord. I used the drain line for the extension cord and the probe wires.

I did not attempt to put the heater up above in the fan/condenser box as you did, but I have to assume the "existing wires" you used were the pink wires to and from the thermostat which was bypassed. I bypassed the thermostat using a pink connector with solderless crimp connectors so that I didn't have to cut the existing pink wires in case I wanted to restore the cooler to normal operations.

The heater I plan to use can run as low as 150 watts (has a fan as well) but I'm afraid it still may be a bit of overkill. I'm hoping I can program the Love Controller to either heat or cool, but not switch back and forth risking burning out the compressor. If not I'll likely add a kill switch for the compressor that I can access externally. The heater can be simply unplugged when in cooling mode.

If you happen to see this post, let me know if you can see any issues with my build. I'll likely be firing it up later today.

Best Regards
Joe