Refrigeration

[RayNWanda]

 We built a shelf for the compressor/condensor unit at the back of the port cockpit locker. The refrigerant lines run behind the stove liner straight into the box (Thanks Dale). The holding plate is mounted on the inboard end of the box. Unfortunately, that makes the most accessable part of the box the freezer. We may add another hatch for the fridge, but that's a wait and see. We did not add any insulation to the box or make any changes to it. I did get some gasket material for the hatch to try to slow heat leakage there. I may add some foam under the bottom of the box later. I am looking at the hatch- My first thought was to eliminate the hinge, foam and fiberglass the hinge area. That would open too big a hole every time the box is opened. I think I am going to try to make some sort of flexible barrier (maybe a sheet of rubber) across that area to cut down leaks, but still allow opening either side.
I was offshore last week, so I got back on it yesterday and finished up the connections to the holding plate. We got the pump installed and the water supply hose in today. All of the refrigerant lines are in and finished except for insulation. The last thing we did today was pull vacuum on the system for a leak test. I'll check the gauges in the morning to see what we have. Tomorrow will be the discharge cooling water and start wiring it up. I hope to have it up and running before I go back to work Tuesday.
We are in the habit of closing the seacocks except the cockpit drains when we leave the
boat. We are getting cooling water from the forward thruhull. I teed into the hose from  the seacock and then installed a block valve downstream in the original line. That valve is there to isolate the rest of the boat when we have the reefer running and are not aboard. Only the reefer will have water.

[eveningebb]

Great!    This project is high on my to-do list, so your thoughts help.  I look forward to hearing how it works, once you get it up and running.  Thanks for the info.

[RayNWanda]

 Startup was today. I had an issue getting power for the Carel t'stat. I'm going to have to pick their brains about that. I finally jumped power to it, flipped the switch and the compressor fired up. I think I got it fully charged, the holding plate was getting COLD! as the temp dropped, I was watching the sight glass and would give it a toot of refrigerant as needed. After 2 1/2-3 hours, the sight glass was staying full. I went out to check it and the head pressure was going through the roof! The cooling pump had decided to take the day off. I shut it down. I played with the pump a little and it is dead. So- now I need to get the pump swapped out before I can do anything else.

[RayNWanda]

 Changed out the pump yesterday, moved the t'stat probe and got it going again. I didn't time it, but after 5-6 hours, the plate was down to 0.8 degrees. We have a mechanical thermometer that will be the fridge thermometer. The sensing bulb was laying on the bottom of the box in about the middle. It was down to 20 degrees. We had tested that thermometer in some ice water and it appears to be accurate. I have not yet built the partition. At 0.8 degrees plate temp, it appeared that the expansion valve shut off and caused the high side pressure to climb to the setpoint of the high pressure switch, which shut the system down. It repeated this 3 times, then I turned it off.
So- we are getting close. It should pull the plate down to -10, then cycle between there and 0 degrees. I am going to try moving the expansion valve sensing bulb a little today and get started on the partition. I think with a little tweaking and tuning it's going to be OK. It was pulling 7 amps at 0.8 degrees.

[RayNWanda]

 The roughed out partition is temporarily installed. It is 2" foam. I had to use 2 pieces to make it, so it has a seam down the middle. I wanted to actually see it work before I cover it with formica, so I had to try to seal it somehow, but leave it moveable. The solution was simple after a little thought. I ran a strip of food cling wrap from the top on one side, down to the bottom, across the bottom to the top on the other side and taped it. I put the partition in place with the cling wrap between it and the icebox, then foamed it. It worked great. After the foam cured, I removed the partition and peeled the cling wrap off it. So now the partition is custom fitted and can be moved somewhat to find the best position for it.
I got the holding plate down to -10 degrees last night and the fridge was 40 degrees. The unit shut down and then immediately restarted at -9.9 degrees. Looks like I need to go through the thermostat programming and check the turn on temp. I want to see it cycle several times before I modify or move the partition. I suspect that the fridge temp is going to come down a little more when we are able to hold the freezer temp down. Once the partition is finalized, I will pull it out, remove the excess foam, cover it with formica, then fix it in place with silicone.

[S/V Deo Volente]

Your installation sounds very much like an updated version of my Grunert system, I have the Pilothouse so the configuration is a bit different, but a couple of things to consider. There is a slot at the top of the divider to let the warm air from the fridge circulate back into the freezer, but I found items at the bottom of the fridge will tend to freeze so I added a small computer processor fan (about 1.5") that runs all the time to circulate the air in the fridge side. Pop or lettuce will still freeze when left near the bottom but it does help move air in the box and keep the temperature more even. It takes a lot more energy to make ice than to just keep it frozen so the ice trays go in low next to the holding plates...and sometimes ice cream next to the ice! Enjoy!

[RayNWanda]

 I have been chasing my tail with long runtime and short downtime. The unit would run 1 1/2 hours pulling the plate down from 0 to -10 degrees, then cycle off for 15 minutes. I was horrified at the power consumption numbers. Today I pulled the plate down to -10 and let the unit shut down. I lifted one of the thermostat wires off the unit so I could use the digital thermostat and it could not restart the unit. I was convinced I had a refrigerator plate in a freezer application. I timed the plate at each degree as the temp came up. What I found is that the plate solution is mixed to work between 10 and 0 degrees, not 0 and -10 like I thought. Dumb mistake- I have spent a lot of time chasing this down. The upside is that it is going to pull the plate down rapidly and then stay off for quite a while. I'll reprogram the thermostat and get some more numbers next week. I'm sure they are going to look a LOT better.

[S/V Deo Volente]

I'm curious as to where your thermostat bulb is mounted, sounds like an awful long run time to pull down 10 degrees.

[RayNWanda]

It is mounted right at the outlet from the plate, 2 o'clock position and insulated. The thermometer probe is on the side of the plate about halfway down and insulated from the box.
I think if we run it between 0 and 10 degrees we are going to have much shorter runtime. My melting time test I ran Sunday showed that from -10 to 0 degrees it was 1-2 minutes from one degree to the next. From 0- 10 degrees, it was 12-16 minutes. So the plate temp rose 10 degrees in 15 minutes because I was trying to work the plate in the wrong temp range.

[Dale Tanski]

Ray,
Damn that phase change!  Sounds like you ate almost there.  Just a bit of fine tuning.  Best of luck.
Dale

[Sta-Sea-Dawn]

I have hull #193 1978.  I just discarded my Grunert refrig unit.  I had talked with Grunert and they told me it would take more to fix than replace.  I have since lost contact info...duh...question...I kept the cold plate it look good, I want to mate a West Marine unit to it.  Is it possible or does anyone have contact info for Grunert?

[PeteW]

What compressor does it have?  Danfoss BD-50 perhaps or is that what blew in the Grunert? Usually its the controller that goes. I'd be interested in getting a blown controller so I can set up a repair exchange on these in my shop. Need to reverse engineer the schematic and bill of materials .  I'll buy from you if you are planning to scrap it.

But can't see it really costing more to fix than replace? Controller is $300 new and goes on with 1 small screw and a 3 pin connector.

Pete W.

[PeteW]

In hindsight that old unit is probably a Danfoss BD3 or 2. Danfoss quit making those and for good reasons. In which case your mechanic is right. Will cost you $750 in just parts to replace that with a newer unit. The new Danfoss DC compressor line feature actual 3 phase motors, hence the controller which switches the DC currents. I believe the old compressors were standard DC motors which are unreliable.

To reuse your hold over plate you will need to invest in a vacuum pump and some gauges and stuff. You will need the same reuseable Areoquip quick connects on the condenser that are on the AC100 you plan to buy.($70 from rparts.com) The older connectors were one time piercing connects. In which case you will definitely have to pump the evaporator  down and pre-charge it prior to connecting to the new pre-charged condenser unit from West marine. I'm currently doing this on my boat. To do this I put shrader valves on the evaporator side, connected the Areoquips together to pump it down and charge it with 134A.  But If you pay someone to do that its going to probably exceed what a whole new system will cost; unless the evaporator connectors are the reusable kind and you feel the system integrity is good. In which case you may end up pumping it down anyway and starting from scratch just to get the any water vapor out and have peace of mind about the system.

I was seeing some perfect sized Isotherm Magnum units on Ebay for $1500. Holdover plates and both halves precharged ready to go.  I pulled up a manual on the Grunert system. Very nice. Coaxial water cooled condenser. The smallest one has a 1/4 horsepower compressor which is big . Not Danfoss, maybe Dometic.  I think the AC100 system is half that capacity with the BD50. And air cooled too. You might be disapointed. But I have some tips on souping up a BD-50F compressor for 50% more capacity if anyone is interested.


Good luck,  Pete W

[Sta-Sea-Dawn]

Wow...Pete,
That info was so far above my head....I have a boat buddy that does refrigeration and he is going to help me.  I will have him read your post.  Maybe he will understand it better than me.  I think you are saying the old cold palte is not worth the trouble.  The biggest reason I wanted to use it, was I did not want to climb in the box and remove the old one and it's connecting coppper tubing.

[PeteW]

A holdover plate by itself can cost $500 to $800 new depending on size. Add another $80 for the expansion valve attached to it. If you have a friend that can do refrigeration I would first see what kind of deal you can get on a new condenser unit. If the cold plate is good and the tubing and connectors are the right it would be a lot of extra work to pull it all out and replace. Trouble is all the deals for a properly sized system for the pearson (such as the Isotherm Magnum 5303 water cooled with twin BD50's & large holdover $1650 on Ebay) I see include a complete system with the holdover plate.

What did they say was wrong with the Grunert condenser unit? That looks like a high quality heavy duty system that in the end might still be worth repairing. Especially if you have a buddy that does refrigeration.

There is a new Adler Babour CU100 condenser unit on Ebay right now for $865. That looks like a smoking deal.  The difference with the Grunert is (and I don't know what your system really is) air cooled condenser vs water cooled and a smaller BD50 compressor. (650 BTU/hr max)  So if you sail the tropics this unit may not answer the mail compaired to what you had.

Glad to help.  Pete W  old hull #6