Alder Barber Cold Machine

The original ice box was about 9 cubic feet and barely insulated, I first installed the cold machine and found it to work well even if using a considerable amount of electricity. Later I cut out the old box from the inside, found that the insulation was mostly wet and ineffective. The rebuilt box has 6 inches of urethane foam insulation on all sides and a 1" thick vacuum panel in the lid which is roughly equivalent. The inside of the box is constructed of 1/2" marine plywood covered with Formica. The result is a very well insulated fridge which consumes about 30Ah/Day when in the tropics. If I place a 1" piece of foam between the evaporator and the rest of the box I have a freezer which runs at about 3 degrees F and the fridge is about 33 degrees F.

The compressor is in the stern of the boat thus dumping its heat outside of the living spaces and is well ventilated. As can be seen from the photograph, there is a bit of corrosion on the base plate which holds the compressor but the compressor itself and the condenser both seem to be in quite good condition. I recently removed the unit from the boat, cleaned it up, removed the base plate, painted everything and reassembled the unit. The system performed as it did before, somewhat underperforming but I wanted to clean up the corrosion issues before dealing with the performance issues in case I damaged the unit in the clean up proces.

Over the years the system has become somewhat less effective, interestingly if the ice box is fully loaded with ice the unit will run correctly and cycle on and off maintaining the ice at about 18F. However with the ice box empty the unit will not pull the ice box down and the best the system will do is about 50F. The recommendation is that the system is compatible with any of the following refrigerants: R12, R409A (Hot Shot), or MP39, with the preference being in that order. This units oil is based on Alkyl Benzene oil which is basically very pure mineral oil. None of the refrigerants are compatible with each other so a complete system pump down is recommended, this will also remove any moisture which may have gotten into the system. Note that the BD25 compressor used in this system is NOT compatible with the modern 134A refrigerant.

When loading the system with refrigerant the weight of refrigerant is referenced to R12 and is dependent on the compressor style (In this case a BD25) and the evaporator style (in this case the small vertical evaporator). Both R409A and MP39 are blended refrigerants and it is recommended that the system be completely pumped down and reloaded instead of topping off as the lighter molecules in the blend tend to leak out leaving the heavier components behind. After pumping the system down loading with the equivalent of 123 grams of R12 the system is basically where the factory loaded it. At this point starting from a room temperature fridge the entire evaporator should frost up completely, there should be no frost beyond the white painted portion of the lines running between the compressor unit and the evaporator. Interestingly these small units can have significant variations in efficiency based upon the refrigerant load, fine tuning the system can significantly impact power consumption. An interesting study would be to adjust the refrigerant load while watching the average daily power consumption to see just how large these variations are.

The access port on the unit is a low pressure port connected to the "service" port. It is a 1/4" Schrader type refrigeration access port common to the older automotive R12 systems.

The folks at WAECO have wonderful technical support, the contact numbers are as follows:
WAECO USA Customer Service - 7 days a week
Monday - Friday
8:00 am - 5:00 pm EST
Phone: 860-664-4911
FAX: 860-664-4912
"After Hours" Technical Support
Phone: 860-ABS-COOL i.e. 860-227-2665
Monday - Friday 5:00pm - 9:00pm EST
Saturday & Sunday 10:00 am - 5:00 pm EST

From approximately late 1994 until 1998 these units used a BD35 which is compatible with 134A and after 1998 a BD50 (134A compatible) compressor was used. The currently available units are similar but with the significant difference that the couplings are no longer able to be disconnected after being assembled (i.e. one time connection). WAECO's observation is that these couplings are less likely to leak with modern (smaller molecule) refrigerants. The systems do have access to both the high and low pressure sides making recharging the system with 134A less difficult. Additionally the side of the compressor unit where the connections are made is opposite from the older units and so if the distance is tight (as it is in my case) a 5' extension tube set (costs about $100) will be required to gain a bit of distance. Note that the attachments are still the 1/4" Schrader type valves even on the modern 134A systems and so adapters are necessary to attach to the access ports. 

The useful life of the compressor is supposed to be approximately 20 years, however, the old BD25 compressors use a different electronic control module which is no longer available so if the module goes the unit is no longer useable without replacing the compressor.   

A good source of refrigeration information on the web is KollmannMarine they sell a couple of books I would like to get a look at to determine if there is useful information there but the information on the web site is wonderful.

Compressor for Alder Barber Cold Machine

The compressor the the Alder Barber cold machine is mounted aft of the Quarterberth. This is at the extreme limit of the tubing provided to connect the evaporator to the compressor/condenser assembly. Other than some minor corrosion issues with the aft location it has worked out well and has been running continuously since 1994.