Having a fridge on the boat was one of the very first things that we did back in 2011 when we got the MJ. I picked up a Norcold SCQT kit at Fisheries Supply in Seattle while preparing to bring her back to Richmond. The Gulf had a huge cooler with an opening in the galley and an opening in the port Lazarette for putting the ice in. Both top load holes were around a foot square. The cooler had a stepped interior with slopes leading to a drain that emptied into the bilge. Pretty standard double fibreglass walled filled with blown foam 3 inches thick. I closed the rear opening sealed it up with caulk then layered the interior with foil covered air filled plastic insulation, and installed the evaporator plate high in the aft side. This arrangement worked very well for us keeping the fridge at the prescribed temp of 3 or 4 degrees C with the temperature control at the lowest setting. That is at 1 on a 1 to 5 dial with 5 being the coldest. Three years ago we bought a Dometic freezer and had that running in the aft Lazarette. It draws 6 amps per hour when running and the fridge draws 3.5, so that is a pretty big drain, although our battery bank easily managed it for a couple of days. The freezer is quite small..18 liters and takes up a big chunk of the Lazarette so I decided to attempt a modification of the existing cooler to turn it into a spillover style freezer/fridge using the Norcold that is already installed. Now I realize that this plate is designed to turn the cooler into a fridge only and not marketed as a freezer unit for that size of cooler. The original cooler is close to 7 cubic feet. As the Norcold unit never worked hard at all to maintain fridge temps, I bet that it would freeze in a smaller space that was well insulated, and the spillover style would accommodate fridge temps. As it is not possible to just remove the evaporator and re-insulate the cooler (without having the system recharged by a pro etc.), I had to add closed cell foam to the cooler and build a dividing wall between the freezer and fridge. So a lot of measuring and 3 x 2 foot x 8 foot sheets of Dow blue board and 3 x 2 foot x 4 foot sheets of formica and a couple of tubes of silicone caulk and a bunch of construction tape later I had a double compartment fridge freezer set up ready to try out.
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Fridge after insulation added
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The dividing wall is made up of 1/4 inch plywood with 1 inch of foam on each side covered with formica. Made in 2 sections caulked together midline with the spillover and return holes in the top section. All of the interior cooler walls were covered with foil covered plastic bubble wrap insulation and then 1 inch of closed cell foam. All seams were taped then formica was glued on to the foam and the seams once again caulked and or covered with vinyl tape. I cut some foam templates for shelves which will be installed using HDPE 1/4 inch material. I had to rebuild both of the top load covers and install lips that will allow for a positive seal, with the freezer door having spring hinges and a positive latch to secure the foam seal. The spillover hole and the return air hole are 1 1/4 inch and I may make them smaller...I turned the compressor on after I had placed the temperature probe into the freezer. Probe was $15 from Amazon..has internal and external sensor as well as a clock and 3 feet of line so it can snake around. I checked it on the home freezer for calibration, as well as the old mercury thermometer on the boat.
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Freezer
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The freezer compartment is smaller than the fridge. After the addition of the extra insulation and the divider, I added 6 inches of insulation to the floor of the freezer so it is around 2 cubic feet and the fridge is 3 cu.ft. I will likely add more insulation to the freezer but initially when I had the temp setting at the level 2 mark and the whole thing empty, the temp went to -9 c after 24 hours in the freezer and was 2-4 in the fridge compartment. When I came back to check it the compressor was not running, but I cannot estimate the duty cycle yet.
I filled up as many containers as I could fit in the freezer as well as one in the bottom of the fridge and left it for 2 days. When I came back to check 90% of the water was frozen solid in the freezer. Only the very top container situated where the warmer air is pushed back into the freezer is located did the water not freeze. The container in the fridge bottom was not frozen, but very chilled. So far this is working out well. I would like the freezer temp to get a bit lower at least to -12 -15 or so. I doubt it will go down to -18 though, but then I haven't properly fitted the door, and can still add more insulation to help it a bit.
The fridge cover..R7.5 foam plus whatever the air pocket foil provides. The bottom of the lid rests on the weather strip in the top of the fridge and the sides fit snugly in the opening.
The two shelves glued and pressed into place made from hdpe board with 1 inch lips screwed on with epoxy as well. The shelf is 11 inches wide by 8 inches deep.
The freezer lid in the lazarette. I glassed on the hinge platform to avoid drilling into the top of the freezer box. The hinges are spring hinges aka screen door hinge so they apply a positive force to the lid at the back while the anti rattle SeaDog latch holds down the front.
Seadog Latch
The lid is R7.5 of foam topped with 1/4 plywood which covers the top and sides and is glassed in place. The bottom of the lid is pressed onto weather stripping that sits on the interior lip. The lid is then positively pressed down to form an additional seal to the outer box top with the air filled insulation same as what is seen on the topside of the lid.
So far the cost for this project has been quite moderate, $100 or so for new parts. Some incidentals from inventory, and of course the existing evaporator. Add that in would be an additional $700. The fridge has been working seasonally for 7 years now in this climate so it will be interesting to see how it will hold up ( the compressor ) with the increased duty cycle if that occurs.
After finishing with the lids I turned on the compressor to see if there was improvement and was happy to see the temp had dropped to nearly -15c.
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| Temp Gauge |
It dropped down to -14.8 when I lifted the fridge lid and the compressor turned on. The freezer was empty for this test so I imagine with pre frozen foods and a few cold shock PCM packs all will be hunky dory.
Picked up some stackable wire baskets to fit in the fridge side in order to utilise that space better....
Freezer tray
may still add some more insulation to the exterior of the cooler in the lazarette but will call it done for now and move on to the next..... October 15,2020..after two journeys with this unit..8 weeks this spring and the same just ending with warm days in the mid twenties centigrade the unit worked as expected. Fridge didn't freeze and freezer didn't thaw. Chicken and beef rock solid and ice cream bars good. There was frost buildup on the evaporator plate though so I am considering closing the two air flow apertures in the divider as I think the moist air is being drawn in from the fridge which is opened much more frequently...will post next year. The duty cycle on the unit appears to be no greater than with the original installation once the set had been attained though this is difficult to ascertain with the basic hardware provided. I tried to get some input from the Norcold tech but they were not helpful.
We have used the freezer for 6 months over the past year and a half. I added some more insulation to the freezer and that helped with the frost build up this last trip. The freezer stayed at -12 and there was no thawing. I keep four 8x10 phase change cold packs in with two on top of the food to maintain the chill. The power draw is minimal with the solar making up the loss readily. I don't think my batteries went below 85% and we anchored for 3 or 4 days at a time without cranking the engine.
Update 2023...
Still working.
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