Originally Posted by Reefer.
Thanks Richard, what is point of having two speeds? Power saving?
Variable speed is becoming the answer to daily energy consumption
. The major improvement pleasure boat icebox
compressor is the ability to balance a system based on ambient heat load conditions. Daily System Coefficient Of Performance (SCOP) is best when all components in a system are balanced together. The compressor has a major effect on efficient performance the faster it runs the more energy is wasted do to loss of volume metric inefficiency and excess heat generation. Slowing down compressor can cut daily power consumption
in half in some cases even though compressor runs much longer. As a general rule
a Danfoss BD compressor should run less than 50% of the time at its slowest speed.
If there is no resistance in thermostat wiring
circuit connected to C and T module terminals and thermostat maintains desired box temperature and compressor runs much less than 50% of the time you have a very energy efficient system.
If your boat has an amp-hr meter run unit 24 hours and record
total amp-hrs. Now without changing thermostat setting change position of switch on black box and record
24 hours usage. As long as box temperature remains at desired temperature amperage consumed will tell you what position to leave the switch in.
Another method of selecting the correct size resistor is make up four sizes of resistors as shown on my web site slide show. First set thermostat to desired box temperature and leave it set there for a day or two. Now with no resistors in thermostat wiring see if box temperature is satisfied by unchanged temperature. If box temperature is too low change resistor to the next size higher ohms until box temperature is satisfied without tampering with thermostat.