Restoration? Servel Fridge

These are absorption fridges. Search for this to get a basic understanding of how they work. These came as mostly propane optioned but some had an electric option as well. If yours is gas based only the burner should be inspected and serviced. I’m sure it could be converted to electric but am unsure how the heating element would be sized. I think the refrigerant mixture is ammonia and water but I may be mistaken. It may be possible to apply heat with a hair dryer or heat gun where the burner is to check if the refrigeration system is intact (evaporator should start to cool). Never played with one but I am actually looking for one myself that is in good shape. Most were bought for peoples cabins in the north.

Hi there. Servel made gas and kerosene fueled fridges, based upon the absorption cycle. They also sold electric vapor-compression fridges, with a more traditional Freon and compressor system. From the front with the door closed, it's not possible for me to tell which design you have; although others with more Servel experience might be able to help.

The absorption system designs will have a grille on the top of the cabinet, toward the back. It will have a literal exhaust vent pipe in the grille. If you open the door, the lower area will have a gas valve and some other easily identifiable parts. If it's an electric model, it will have a compressor in that area.

If you can get a picture of the mechanical parts, I can identify it for you.

If it is gas powered, the system is based upon some rather complex physics principles. The sealed system contains a mixture of water, ammonia and hydrogen. The working fluids circulate because the densities are very different between the three. The lightest gas, hydrogen, rises to the top due to gravity. The water, being heaviest, falls to the lower parts of the system - again by gravity. The ammonia is in between the two and will remain in the central areas. Even though the entire system is at one constant pressure, the ammonia will boil off in the evaporator due to the concentration of ammonia being very low since the hydrogen is in that area mixed with it. The vapor of ammonia is highly attracted to water, so it is absorbed into the water in the lower area of the system. The water flows through a boiler, which separates the ammonia vapor from the water, where it can cool, condense, and repeat the cycle.

While in theory, an electric element can be used to drive the absorption cycle, it uses about 10x the energy versus a compressor based system. I have used a heating element to temporarily test an absorption system, but that was just to prove it was good before investing in gas valve and burner parts. It's not something you would want to do for normal operation. For instance, the power input was a continuous 500W to get the fridge to work normally. A similar size comrpessor system uses about 120 watts and only operates about half of the time.

Sincerely,
David