14 November 2012
This past month has been devoted to the refrigeration system. Allegria had a Grunnert holding plate system for the refrigerator and freezer in place when we bought her in 1994. It was original equipment on the boat, so it was about 10 years old at that time.
The system was powered by a 90 volt DC motor which could be run with shore power or by an alternator on the engine. A large compressor cooled holding plates in the refrigerator and freezer compartments which were filled with a eutectic solution which froze at a very cold temperature. These plates would freeze when the compressor ran and keep the boxes cold.
This system worked well and was state of the art at its time. There were problems though. For one thing we had to run the engine every day to cool the boxes and the other was that the system used R 12 (Freon), which hard to find and environmentally bad. A year or so ago I switched to a 12 volt DC motor which ran from our battery bank and was supported by the solar and wind chargers and that solved the engine running dilemma and things ran fine. When we needed to top up the refrigerant we switched over to and new R12 replacement called Hot Shot which is a blend of more environmentally sound compounds. It worked well but we began to have more trouble with leaks in the system and it became obvious that the age of the system was catching up.
We finally decided to switch over to a more modern system made by an Italian company called Frigiboat. This system has a small compressor for each box and an evaporator plate instead of a holding plate. It is more like the refrigerator in your kitchen. It also runs the refrigerant though a heat exchanger outside the boat called a keel cooler and eliminates the need to pump water into the boat to transfer the heat out of the refrigerant. All this results in it being more efficient (requires less energy).
At the same time I decided to add more insulation on the inside of both boxes. Once the old equipment was removed I added 1.5 inches of insulation on all sides and filled in the bottom of the freezer. This added considerably to the already existing insulation and should also result in further efficiency. I also modified the doors to the boxes and added insulation and another seal on each.
The system is up and running and cooled the boxes down very fast so I’m hoping we will be happy with its performance. See pictures of the old and new in the Photo Gallery. Now that this project is done I should have time for more frequent posts and we’ll look at some of the other improvements and upgrades to Allegria.