AB cold machine, compressor air flow ideas....

[pressuredrop]

I am installing a new ab cold machine in my little herreshoff 28. The compressor will be mounted in the cockpit locker behind the ice box

When i read the instructions this locker surely does not meet the ventilation requirements... and will often be crammed full, even around the compressor... not good i know...

I am thinking to build a box around the compressor (to protect it from the contents of the locker), and install a blower and ducting to pull air in from the cabin and discharge it into the cockpit...

I feel good about this plan other than the additional amp draw of the blower... has anyone ever done anything like this?

Also where should i connect the blower power on the compresser so that the blower kicks on and off with the compressor and is not always running when the fridge breaker is on?

Thanks
Ben

[a64pilot]

You could tie into the fan wire and use a relay so it only draws the power required to close the relay, I believe you can only pull a low current from the fan wire before the controller shuts down.

You could also not touch the compressor wiring at all and use a thermistor to turn the blower on and off based on air temp inside of the locker.

[Coolerking]

I don't think the module that drives the system will support the additional load of a 2nd fan, I could be wrong, and maybe Richard will chime in on this, but you could run external power and control the fan with a cheap tstat that cycles on then the space gets warm.
Also many of the units come with a plenum designed to accept a duct to pull air to the condenser from outside the space its mounted in. You might be able to order one for the very unit you have.

[Richard Kollmann]

A new AB would indicate it is CU100 or CU200 that has a 5 amp fuse on panel designed to carry a secondary fan or water pump. The primary condenser fan circuit is limited to 1/2 amp. It this unit is operated on 24 volts the fans are still 12 volts.

[pressuredrop]

Richard i know your the expert here... any thoughts on boxing in the compressor and forcing air around it?
Would it be better to put the blower on entrance or exit to the box... my guy says exit...

[Richard Kollmann]

Think of it this way heated air from refrigeration must be disposed of outside box it is installed in and mixed with cabin air or dumped into bilge. We are only dealing on average 300 btu per hour, about the same a a person moving around in boat.

There are two good ways to move this heat from heated area:
1. Install a second fan blowing air into compartment that will tend to pressurize the area, then provide exit holes for heated air to escape.
2. The most efficient way to control condensing unit and compressor heat is to position unit so condenser fan is sealed against a louvered opening drawing cabin air in and through condenser and fan. Again there needs to be holes for heated air to escape.

If you do not exit heat and bring in ambient air from cabin your unit will not be efficient. Air temperature interring condenser should be less than 90 degree F.

[stormalong]

A cockpit locker would not be a good location for the compressor. Besides the ventilation issue you already identified salt water exposure would be a killer. Corrosion would destroy the controller module and the circuit board. The cold machine comes with fairly long tubing. Take advantage of that and find a better place.

[Cpt Mark]

These little fans are good for 7cfm which is more than you'll likely need, are tiny and use almost zero current. I have them in my fridge and freezer

[Scott Berg]

I'm with Richard; we often pump in cooler air from bilge areas for exactly this purpose

[Richard Kollmann]

Originally Posted by Cpt Mark

These little fans are good for 7cfm which is more than you'll likely need, are tiny and use almost zero current. I have them in my fridge and freezer

Seven Cfm fans are OK for tumbling air inside refrigerator but 30 to 80 CFM is required to dispose of refrigeration process heat.

[onestepcsy37]

i had a similar problem with my cold machine. i was able to install it just inside at the aft cabin bulkhead. i ran a short hose through a hole i cut in the bulkhead and it vented into the port cockpit locker. i added a louver door vent on the locker side like they use on clothes dryers. worked great.

i also had a computer fan that i added to the box where the unit lived. it insured that cooler cabin air would blow over the unit. i put it directly above the computer module. as mr. koillman will tell you, keep that module cool.

don't know if they still have this on the cold machine. it was designed to be not only air cooled but also water cooled if you wanted it. i didn't want it, per advice from mr. kollman. to piower the pump there is, or was, an output on the control module for it. i plugged my computer fan into that output and it turned the fan on every time the unit started up. no special wiring required.

had mine for ten years before we sold the boat and had zero problems with it after the initial start up problem. which ab fixed immediately. free.