Pulley Recommendations for Type II Bitzer Compressors
We have assembled the combinations below for the convenience of those customers who want to put together new motor/pulley/compressor combinations. The load and, consequently, motor capacity required varies depending on the type of refrigerant used and the condensing and evaporator temperatures. The recommendations and resulting capacities given below are based on a condensing temperature of 105oF (40oC) and an evaporator temperature of 15oF (-9oC) for the refrigerator and -10oF (-23oC) for the freezer. These are typical of a water-cooled marine holdover plate application. If your operating conditions vary much from those specified you may need to change drive ratios to prevent overloading of the motor and/or maximization of system capacity.
A final caution - You will know that you are overloading your motor if the system draws too much current. A 1/2 hp 12v motor should not draw more that 40 amps for more than about 5 minutes during normal cycling (most systems will temporarily "overload" when first freezing down a warm plate). For a 1 hp 12v motor the maximum is 80 amps. For 24v system cut the maximum current in half.
Combination #1 - Direct Coupled
Refrigerant: R-134a
Motor: 12v or 24v Glacier Bay "LS", 1/2 hp, 675 rpm
Motor Pulley: Direct Couple Kit
Compressor Pulley: None
Resulting Compressor Speed: 675 rpm
Capacity: Refrigerator 2,779 Btu/Hr (815 watts), Freezer 1,466
Btu/Hr (430 watts)
Combination #2 - Belt Drive
Refrigerant: R-134a
Motor: 12v or 24v Glacier Bay "HS", 1 hp, 1,800 rpm
Motor Pulley: 5.45"
Compressor Pulley: Standard (included w/compressor)
Resulting Compressor Speed: 922 rpm
Capacity: Refrigerator 3,785 Btu/Hr (1,110 watts), Freezer 2,012
Btu/Hr (590 watts)
Combination #3 - Belt Drive
Refrigerant: R-404a
Motor: 12v or 24v Glacier Bay "HS", 1 hp, 1,800 rpm
Motor Pulley: 3.25"
Compressor Pulley: Standard (included w/compressor)
Resulting Compressor Speed: 570 rpm
Capacity: Refrigerator 4,058 Btu/Hr (1,190 watts), Freezer 2,182
Btu/Hr (640 watts)