With the temps in the low 30s and a snowstorm in the forecast tomorrow, I decided it was high time to install new refrigeration! Well, not really; I had been planning it for a while and originally thought I wouldn't get to it until the spring but a few weeks back I decided to put the mast rewiring project off until spring instead.
When I purchased the boat it had an engine driven cold plate system that reportedly worked when the boat was last in the water in 2013, but it probably used the old refrigerant type instead of the new 134A and it just took up so much space in the engine compartment. I just didn't want to deal with engine driven compressors, belts, hoses and a series of unknown 'doodads' that probably did something, but I was not interested in finding out. So I ripped it out when I re-did the engine compartment with the plan of installing an economical electrically driven system.
I had a number of systems in mind but finally ended purchasing an Isotherm Compact Classic 2012. It seemed like a good combination of cost, cooling volume, and ease of installation (the system is pre-charged with quick connects). The nice thing about the 12v electric systems is that they can be located in a number of locations as long as there is sufficient air flow to keep them cool. They essentially consist of 3 parts, a compressor that can be remotely mounted, an evaporator plate that lives in the icebox, and a thermostat controller that can be mounted in or outside the icebox. The one caveat of the thermostat is that one side has a temp sensor capillary tube that needs to be mounted on the evaporator plate and the other side has wires that lead back to the compressor.
After scouting a number of locations, I decided that a shelf in the port lazarette behind the icebox would be a good location for the compressor because of its close proximity to the icebox, good airflow, and mostly out of the way location. The only issue with this location is that the shelf is sloped downward toward the side of the boat, so this would have to be leveled (the compressor should be mostly level).
I measured a 19 degree angle of slope for the shelf that I planned on mounting the compressor on and decided to put the 3d printer to use by making 2 - 19 degree wedges with holes for 2 bolts on each one to mount to the shelf. I used an extra strong print profile (15% infill and 6 solid layer walls) that should have no trouble holding the 15 or 20lb weight of the compressor. I epoxied a 6"x12" piece of 3/4 inch marine plywood to the blocks and tapped the 1/4" bolts that will mount the assembly to the shelf. Finally, I through bolted the compressor bracket to the assembly and got ready to install.
I'll say up front that this was not a difficult job, but I was worried about installing the evaporator and snaking the copper tubing out of the icebox and aft to the compressor. The tubing is pre-bent in a coil and I couldn't help but think that it would be really easy to kink the tubing if not careful. Additionally, the evaporator plate comes flat and it is longer than the length of the icebox, so it needed to be bent. Fortunately, the kit comes with a bending 'dowel' that you screw down to a piece of plywood and use it as a form to bend the evaporator around at specific locations.
Last week just before Thanksgiving, my son and I decided to tackle the evaporator installation. We carefully carried the bent evaporator up the ladder to the boat and started straightening out the coil once we had it in the cabin. First we fed the tubing into the icebox and led it through the hole (from previous installation). Once through the hole it had to be carefully bent around a corner and through a 1.5 inch hole I had drilled in the bulkhead and fed up to the shelf in the lazarette. This is definitely a 2 person job because the copper tubing is fragile and kinking it would be a very expensive mistake. Once we had the the tubing roughly run to where the compressor would be mounted we carefully slid the rest of the evaporator into the icebox and secured it to the vertical walls with screws that ran through 4 plastic mounts that keep the evaporator off the wall by about 1/2".
With that completed, it was time to mount the thermostat and capillary temperature sensor. I decided that it would be easiest if I just mounted it in the icebox in an out of the way location above the evaporator plate. This made mounting the temp sensor quite a bit easier than mounting it outside the box. Finally, I ran the thermostat wires out the icebox and alongside the copper tube to the compressor location.
The most demanding part of the entire job was running power. I was determined to make the installation orderly and not a haphazard jumble of wires like I've seen on so many boat (many of them mine). I really should have done this before I re-installed the engine, because I had to run the wire along a bundle just above the engine and not easily accessed. I ran the 10/2 duplex wire from the panel down through the battery compartment and over to the bundle that services port side power needs. I had to cut most of the zip ties off the bundle and snake the wire through, re-zip tying along the way. Once I had it over the port side I ran the power wire alongside the thermostat wiring and copper tubing up to the compressor location. There was a lot of boat yoga, but I'm happy that the wiring is tidy and well secured.
With that complete, I through bolted the compressor mount assembly to the shelf and then snapped the compressor onto the assembly bracket; the isotherm bracket is a nice piece of kit and allows for a quick removal of the compressor should it need to be taken out (still have to unplug wiring and evaporator tubing though).
Next, I crimped and shrink wrapped the power wiring and plugged the thermostat wiring into the controller on the compressor (everything is nicely labeled). The final step was to connect the 2 copper refrigerant lines that come from the evaporator. I cleaned up my mess and insulated the copper tubing from the compressor and zip tied everything so there will be no rattles (and subsequent chafing) in the future.
I still plan on making a plywood 'partition' around the compressor so nothing bangs into it from the lazarette and no errant water spray hits it, but I'm happy to report that even though it was only 35 degrees F in the boat today, I started up the compressor and the evaporator became noticeably colder within a few minutes.
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