Q: How does refrigeration work?
A: A refrigeration system consists of four main parts: compressor, condenser, evaporator and a metering device. A compressor can also be called a vapor pump, because its purpose is to pump vapor (liquid cannot be compressed, and can cause compressor damage if attempted). It pumps high pressure vapor into the condensor where either a fan or pumped water is used to remove the heat, which causes the vapor temperature to drop below its dew point, where it condenses into a liquid. As it changes state it releases a large amount of "latent" heat, which is the heat energy required for the refrigerant to change from liquid to vapor and from vapor to liquid. This is how the refrigerant "carries" the heat from your refrigerator box to the location of your condenser. At this point the refrigerant is in a high pressure liquid form and is pushed through the metering device, which separates the high pressure side from the low pressure side. In the case of our refrigerators the metering device is a capillary tube (cap tube for short). It is a long length of very tiny copper tubing with a tiny orifice bored through it. After it passes through the cap tube the liquid refrigerant squirts directly into the evaporator, which is at a low pressure because the outlet of the evaporator connects to the suction side of the compressor. At this low pressure the refrigerant quickly boils off into a vapor. As it changes state from liquid to vapor it absorbs heat to facilitate the process. This is similar to the way that boiling water requires heat to change from liquid to a vapor, while maintaining a constant 212 degree temperature. This is the latent heat that will later be rejected out of the condensor, and this absorbtion of heat is what cools your refrigerator box. All of the refrigerant boils off into vapor and is sucked into the compressor to repeat the refrigeration cycle again and again.
Q: What temperature should I keep my refrigerator and freezer at?
A: Short answer: 35 degrees for the fridge, and 10-15 degrees for the freezer. Long answer: It is important to keep your fridge temps below 42 degrees to prevent potentially hazardous bacteria from being able to grow on your food. To keep dairy and meat products from spoilage the closer to freezing the better, however you don't want fresh produce to freeze, so 35 degrees is usually a good compromise. If you want to keep ice cream hard in the freezer, it will need to be about 5 degrees. The reason we recommend 10-15 degrees is because you will use 20-25% less power by keeping it at that temperature. Considering that the fridge/freezer is usually the largest draw on a boats battery bank, 25% less power consumption seems like a no brainer... unless you REALLY love ice cream.
Q: What number setting should I set my Sea Freeze thermostat to for those temperatures?
A: Most of our refrigerator/freezer combinations have the thermostat sensing bulb in the freezer compartment. Set the thermostat somewhere between 4 and 6 to maintain proper temps and the best efficiency. This is also the proper setting for our deck freezers, unless you want to run the deck freezer at refrigerator temps, in which case you would set it between 1 and 3.
Q: I had somebody come look at my boat refrigerator and they told me my compressor is bad, but its only 5 years old, why did it fail so quickly?
A: Theres a 95% chance theres nothing wrong with your compressor. The Danfoss compressors we use are very robust and rugged, and should give you 15 years or more of reliable service. It is FAR more common for the compressor control module to fail due to water damage or power supply irregularities. To an inexperienced technician it will look like the compressor has failed, and they know if they replace the whole compressor sled it will probably solve the problem (even though they don't actually know what the problem is), plus they get to charge you four times as much for a new compressor than a control module. A compressor can be damaged in a few ways, such as a massive refrigerant overcharge where the compressor has to try to pump liquid, which doesn't compress and can warp the valve plate, or by running a keel cooled system or water cooled condenser system with the boat out of the water, which can cause overheating and potentially cause head gasket failure. To verify that the motor windings haven't burned out (which is unlikely), check them with an ohm meter. You should read between 1.5 and 3 ohms between any two of the three pins.
Q: How often should my compressor cycle on?
A: You can expect your compressor to cycle on 40-60% of the time. This is called the duty cycle. This is determined by many factors such as ambient temperature, insulation thickness, compressor capacity, door seals, how often the door is opened, condenser airflow, warm product being added to the fridge, and so on and so on.
Q: What type of refrigerant do your refrigerators and freezers use?
A: We use R-134a, the same refrigerant used in automotive air conditioners and household refrigerators. For freezer cold plate systems or other applications where very low tempertures are required we use 404A refrigerant.
Q: What are Aeroquip fittings?
A: Aeroquip fittings are specialized self sealing couplings that allow us to seperate the compressor sled from the copper refrigerant tubing that connects to the evaporator in the refrigerator, without losing the refrigerant charge. This allows us to properly charge our conversion kits and our remote compressor refrigerator boxes, then seperate the compressor to ship to the customer for installation. Once the compressor has been installed in its location, and the fridge or evaporator has been in installed in its location with the connective tubing snaked through to the compressor, the Aeroquip dust caps can be removed and the couplings can be connected to their mates with a wrench. As the couplings are connected the internal spring loaded valves open and allow refrigerant to flow through them. If the unit ever needs to be moved, the Aeroquips can be disconnected without fear of the refrigerant leaking out. You can see a cutaway of the Aeroquips here.
Q: What is a Cold Plate System?
A: See our Cold Plate System page for more information.
Q: Can I get replacement parts for my Sea Freeze refrigerator or freezer?
A: Yes! We can sell you replacement fans, thermostats, motor controllers, door latches and pretty much any other parts we have used to build our refrigerators over the years, just Contact Us.
Q: Does Sea Freeze offer a warranty?
A: Yes, we offer a Limited Warranty of 1 year Parts and Labor, and 5 years on Air Cooled Condensers, Dura-Coil Evaporators and DC Compressors, parts only.