Compressor replacement

[sailing_gal]

Very interesting information, thank you Richard. I have another question: What do you find the normal temperature differences between the air inside the refrigerator or freezer compared to the thawing temperature of the glycol mixture?

[Richard Kollmann]

Originally Posted by sailing_gal

Very interesting information, thank you Richard. I have another question: What do you find the normal temperature differences between the air inside the refrigerator or freezer compared to the thawing temperature of the glycol mixture?

I like +27 Degrees F For refrigerator Eutectic Freeze point. But keep the eggs and lattes from touching plate. Remember when compressor is stopped by thermostat solution may be 10 to 20 degrees below the eutectic temperature. Once compressor stops there will be little energy stores so plate temp will quickly rise to its mixture eutectic temperature. Now this 27 degree temperature will rise very slow till majority of ice is gone then quickly increase to ambient product current temperature.

I like +6 Degrees F for Freezer eutectic Freeze point for 2 to 3 weeks store meats, For longer storage of chicken, fish and meats it normally requires very good insulation and temperatures below Zero Degree F.
These Freezer temperatures are based on food flavor not spoilage limits.

Freezer Boxes need natural air tumbling passages around frozen food or evaporators that surround product. With Holding plates wood rails down one side of box extending across bottom and up the other side. This allows warm air to to rise and cool air to descend helping to normalize box temperature.
When you can not improve overall frozen product temperature rotate product around in box.


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[sailing_gal]

Thanks, that is along the lines of what we were thinking. I could never get my old freezer much below 25F. So we are increasing the glycol solution for that plate plus adding a "tunable" expansion valve. The old one was not adjustable.

[Richard Kollmann]

Originally Posted by sailing_gal

Thanks, that is along the lines of what we were thinking. I could never get my old freezer much below 25F. So we are increasing the glycol solution for that plate plus adding a "tunable" expansion valve. The old one was not adjustable.

The correct Expansion valve for eutectic plates has a temperature range from +40 to -40 and you operate on the default super-heat position. Allow thermostat to control plate temperature. And it TXV capacity is not too large for 1/5 HP compressor this valve with R134a refrigerant should achieve temperatures below zero degrees F. If too much frost is visible on return line towards compressor adjust super-heat.

[sailing_gal]

Thank you! Yes, that is the plan. He did mention using the super-heat position, testing it and if necessary, tuning it. The TXV we have was properly sized for the compressor, I seem to remember something like 00 or 000- a very small one. Your advice is greatly appreciated.

[Coolerking]

Sounds like you have a Danfoss TXV with an 00 oriface.

[sailing_gal]

Yep, a T2.

[sailing_gal]

Quick update- things are proceeding. The latest time delay issue was the serious re-insulating of the fridge box. I discovered that the top edges of the box, where the sides and the ceiling meet- were not sealed! There was a major air leak that I managed to trace into an opening to one of the lazarettes. So, I have drilled lots of holes throughout the box and filled all open spaces carefully with polyurethane foam, I now have to gelcoat over those holes. Meanwhile, we are examining the situation with the 3 holdover plates I am reusing from the old SeaFrost. I am changing the solutions to allow colder freezing in the freezer (30% mixture), and a bit less freezing in the fridge (10% mixture). My old system had 2 holdover plates in the freezer (and one in the fridge) and I am considering getting rid of one of them. The freezer is about 3.5 cubic feet. I am being told that one will be plenty, the compressor I have for it has a low max temp of -30C. Just looking for additional confirmation from the experts here. (I'm one of those types of people who always has to have more than one opinion for confirmation.)