Upgrade old belt-drive system

[Mickeyrouse]

I’ve been struggling with this problem for years: I have an old belt-drive system that is a current hog. Besides, it leaks refrigerant. For lotsa obvious reasons, I’d like to upgrade. On the un-proven assumption that the coils and lines are sound, I’m thinking it should be possible to simply uncouple the old compressor, remove it and the drive motor, secure a Danfoss in, wire it, hook up the lines, get it charged and balanced, and I’m back to cold beer.
The existing system has R-134/Hotshot in it, replacing the R12 it was born with. The Google tells me that R12 is replaced with R134, so there should be no need to worry about oil compatibility, orifices, etc since nothing past the couplings would change, including refrigerant.
I of course would get a qualified refrigeration tech to do this?
What am I missing? How have I over-simplified this?

[OzeLouie]

The various refrigeration components, evaporator, compressor, condenser, pipe sizes (to ensure correct velocity and therefore oil return etc) must be engineered to compliment each other, otherwise you will only create another power hungry, troublesome situation.

Strongly recommend you dispose of all the existing equipment and replace with a new DC system selected after having a 'Heat load and Power consumption estimate' done on your cabinet to enable choosing the most suitable equipment for the job and to provide you with a guide as to daily power requirements.

[Coolerking]

The shaft seals all leak.
I assume you have txv's and eutectic plates.
Oze has it correct.
Start from scratch.

[Richard Kollmann]

Originally Posted by Mickeyrouse

I’ve been struggling with this problem for years: I have an old belt-drive system that is a current hog. Besides, it leaks refrigerant. For lotsa obvious reasons, I’d like to upgrade. On the un-proven assumption that the coils and lines are sound, I’m thinking it should be possible to simply uncouple the old compressor, remove it and the drive motor, secure a Danfoss in, wire it, hook up the lines, get it charged and balanced, and I’m back to cold beer.
The existing system has R-134/Hotshot in it, replacing the R12 it was born with. The Google tells me that R12 is replaced with R134, so there should be no need to worry about oil compatibility, orifices, etc since nothing past the couplings would change, including refrigerant.
I of course would get a qualified refrigeration tech to do this?
What am I missing? How have I over-simplified this?

There are a number of reasons why your plan will not work:

The box on that boat even new was not designed for a small 12 volt refrigeration system that is probably why the larger belt drive unit was used.

A Danfoss BD 12/24 volt compressor is not compatible with any part of the old system.

The oil and other contaminates left after flushing are a serious problem for compressor's new oil not to mention how to cool a hermetic sealed compressor.

The only technician you would find to follow your up grade plan would be skilled in Hell.

The advise given to replace complete is good but do not expect much from small 12 volt systems unless the system manufacturer will post a cash performance bond.

Questions
Do you know many amp-hrs a day the old unit consumed?
What temperature was the old system set to maintain in box?
Was there ever condensation on box's exterior ?
I assumed the old system was water cooled ?
I also assume Gulf Coast cruising water temperature?

[Mickeyrouse]

When my box was new ( 1973) I don’t think the Danfoss hermetic 12 v compressors were on the market- refrigeration of any kind on yachts was extremely rare at the time. I’m convinced of the incompatibility of my proposal, but don’t understand quite why yet it’s so just yet. This is branching off into the hypothetical at this point, but it seems if a new compressor is designed to run on R-134 and it’s related oil, and if that’s what’s in the system at present, I’m not grasping the conflict. As far as cooling the compressor are it’s needs any greater the present set up? There is certainly room for a fan.
In other parts of the question, I’m starting to accept that the other copper parts of the system are probably getting brittle and would be leak-prone. After all, this reefer has seen 48 years of service. It worked well when she worked- kept ice cream hard in Florida summer.

[Mickeyrouse]

Old system was not water cooled, and would draw 36 amps at start-up, setting down to 21. Condensation only started forming recently. Kept ice cream hard in Florida summer.

[Richard Kollmann]

Originally Posted by Mickeyrouse

Old system was not water cooled, and would draw 36 amps at start-up, setting down to 21. Condensation only started forming recently. Kept ice cream hard in Florida summer.

A better solution for you if your problem is normal loss of refrigerant over time common on that age of systems is to remove refrigerant from system FIRST. Then with no pressure in system check oil level in compressor if low add Castrol iso 100 refrigerant oil to proper level and re-service with R134a without additives available at Walmart. Correct refrigerant charge on that unit is around 18 normal amp draw. Hotshot is a blended refrigerant serviced as a liquid and is not recommended for a system that might loose small amounts refrigerant over long periods of time. Yes, I know this method goes against the rules and today's standards. What have you got to lose when you except the fact your present 1/3 HP system could not function with a 1/12 HP Dunfoss compressor. A boat's insulated refrigerated box as old as yours 1/3 HP refrigeration may be necessary.

[Mickeyrouse]

Problem resolution:
After literally many years of agonizing and soul-searching and much well-meant advice, I have finally removed the old museum piece 48 year-old Grunert refrigerator. No small task- figuring out how to get the old evaporator coils out without destroying the reefer chest was no small puzzle, but now it’s done.
SeaFrost is fabricating a custom set of new coils as well as providing the dual air-water cooling system and pre-charged lines. I’m hoping that installation will be less of an ordeal than removal.
Amazingly, since removing the system I have encountered two owners of similar boats with even old Grunert systems. They swear by them and don’t have the concerns of energy consumption I do. But they recognize the risks of compressor parts availability ( Tecumseh ceased offering replacement parts about 25 years ago) so I’m giving the old compressor skid to one of them.

[JoeM128]

Having similar struggles here
Have 1989 J44 (Sirena Bella) that is starting to act up. I’m in St Martin and have been advised to rip out the old seafrost engine/110V system and replace it with a 12 volt system.
The technician swears by the new systems
Any additional thoughts that may be integrated into this thread are most appreciated. No intention of hijacking the thread only adding to the conversation.

[Richard Kollmann]

Originally Posted by JoeM128

Having similar struggles here
Have 1989 J44 (Sirena Bella) that is starting to act up. I’m in St Martin and have been advised to rip out the old seafrost engine/110V system and replace it with a 12 volt system.
The technician swears by the new systems
Any additional thoughts that may be integrated into this thread are most appreciated. No intention of hijacking the thread only adding to the conversation.

Yes there are small advancements today in your type refrigeration unit but none ivn12 volt refrigeration that might improve the cooling capacity of your existing system. You can calculate the energy used for the old refrigeration per day.
The question then is the new 12 volt system able to produce the same amount of energy as the old system, and will your on board power generating grid support all your 12 volt requirements? You need to be concerned about capacity not which one is more energy efficient. If your present box is less than 7 cubic foot and present temperature difference between box interior temperature and box exterior is insulation is less than 6 degrees F, switching to 12 volt unit is smart.
I have worked in the past with Technicians there explain this capacity question to them and get a good understanding of what they believe the daily energy performance of 12 volts will be on YOUR boat.

[Bowdrie]

Originally Posted by Mickeyrouse

Amazingly, since removing the system I have encountered two owners of similar boats with even old Grunert systems. They swear by them and don’t have the concerns of energy consumption I do. But they recognize the risks of compressor parts availability ( Tecumseh ceased offering replacement parts about 25 years ago) so I’m giving the old compressor skid to one of them.

Kind of like a Model A Ford, while Ford doesn't build them anymore you can still get most of the parts needed to build a new one.
https://compressors.nationalcompress...ve-compressors
Just a few years ago the owner of a 1961 Chris Craft had me remove the original 32V. belt drive system and replace it with a "modern" Norcold unit.
The old system was working just fine, it was the old metal-lined box with poor insulation that caused the unit to draw a lot of power thru extended run time.
I see that you've already sprung for a new system, but a BTU of heat in the box is still a BTU that needs to be removed from the box.
Various types of systems can change the rate of heat removal/run times over a 24hr period, but the cumulative energy used is by-an-large the same.
There are no magic bullets, you're just trying to manage the energy production and storage parameters.

[Richard Kollmann]

Originally Posted by Bowdrie

Kind of like a Model A Ford, while Ford doesn't build them anymore you can still get most of the parts needed to build a new one.
https://compressors.nationalcompress...ve-compressors
Just a few years ago the owner of a 1961 Chris Craft had me remove the original 32V. belt drive system and replace it with a "modern" Norcold unit.
The old system was working just fine, it was the old metal-lined box with poor insulation that caused the unit to draw a lot of power thru extended run time.
I see that you've already sprung for a new system, but a BTU of heat in the box is still a BTU that needs to be removed from the box.
Various types of systems can change the rate of heat removal/run times over a 24hr period, but the cumulative energy used is by-an-large the same.
There are no magic bullets, you're just trying to manage the energy production and storage parameters.

There are now phase three refrigerant compressors where pully drive shaft seal is not carrying any of the load. Another big mistake in the past was not keeping resident frequency vibration low and not exceeding manufacturers design speed limits, and last a reducing of TXV tonnage preventing liquid damage on start up pump downs.