Welcome to PWT's "COOL" section

We've been mucking around with fridges for a while now and the conclusion we have come to is that while portable refrigerators are good for many applications, nothing quite beats a properly made, custom built, affair, this is especially so on a boat. On a boat you may not have the luxury of being able to plug into shore power. You will probably be relying on your solar and/or wind systems sending power to a, (probably too small), battery bank. This is when 100mm of polyurethane insulation all around the box really pays off. Danfoss comressors coupled to a suitable evaporator plate will make your custom made fridge a very viable option to a car fridge.

Please note that due to Waeco Pacific sales policy we will no longer
be supplying Waeco products.

The heart of your fridge system is the compressor, we have the two, the BD 35, (80 series) and the BD 50, (90 series). I have built a 60 litre fridge into my own boat and I am using the smaller BD 35 coupled to a VD 09 evaporator plate. Within the plate will give me around 20 litre of freezer and the rest will be refrigeration. I have 100mm of polyurethane foam around the sides and bottom and 50mm on top.

Evaporator Plates & Fridge component kits:

Max Fridge/freeze size 125 / 40 litres
Evaporator type - 'O' 210 x 240 x 95
Compressor BD35F 270x160x155
Average comsumption A/h 0.6
Max Fridge/freeze size 150 / 50 litres
Evaporator type - 'O'230 x 320 x 100
Compressor BD35F 270 x 160 x 155
Average consumption 0.7
Max Fridge/freeze size 200 / 65 litres
Evaporator type 'O' 270 x 380 x 140
Compressor BD35F 315 x 160 x 155
Average consumption 0.9
Max Fridge/freeze size 125 / 40 litres
Evaporator type 'L' 400 x 170 x 210
Compressor BD35F 270 x 160 x 155
Average consumption 0.79.00
Max Fridge/freeze size 60 / 20 litres
Evaporator type Flat 350 x130
Compressor BD35F 270 x 160 x 155
Average consumption 0.6
Max fridge/freeze size 170 / 55 litres
Evaporator type - Flat 815 x 210
Compressor BD50F 315 x 160 x 155
Average consumption 0.9
Max Fridge/freeze size 200 / 65 litres
Evaporator type - Flat 1200 x 190
Compressor BD50F 315 x 160 x 155
Average consumption 1.0
Max Fridge/freeze size 260 / 85 litres
Evaporator type - Flat 1000 x 270
Compressor BD50F 315 x 160 x 155
Average consumption 1.1
Max Fridge/freeze size 400 / 140 litres
Evaporator type - Flat 1370 x 300
Compressor BD50F 315 x 160 x 155
Average consumption 1.2

These 12-24 volt fan cooled refrigeration units are suitable for mounting in new or existing ice boxes. The fan cooled compressor can be mounted up to two metres away from the evaporator box or plate. Box type ‘O’ evaporators provide an internal freezer compartment as well as cooling the entire refrigeration compartment. Units are supplied pre-gassed with re-openable quick fit connectors for ease of installation. A choice of ‘O’, ‘L’ and flat evaporators are available. Flat evaporators can be carefully formed to suit box size.

Low voltage cut off and radio interference suppression are fitted as standard. Temperature is adjusted by a rotary thermostat incorporating an on/off switch. Connection of the evaporator plate to the compressor requires only a 30mm hole to be drilled in the ice box compartment wall. Utilises R134A ozone friendly refrigeration gas.

1) Reduce maximum box volume by 10 - 20% in tropical conditions.
2) Freezer volume is calculated at approximately one third of the refrigerator volume capability.
3) Freezer thermostat required if used as freezer.
4) Average power consumption calculated at +6ºC in refrigeration space using a typical cooler box with standard insulation at an ambient temperature of +22ºC
Quick Mount, Thermostats, Extension Hoses, AC to DC Converter.

Marty's note

I did some extensive testing on a stock standard 40 Litre Waeco car fridge, which uses a Danfoss DB35 compressor. The testing went for several months and ranged from a mid Winter's day with the fridge full and not used to a mid Summer, hot, humid day, with the fridge being used as it might if you were out and about and looking, as you would, for a cool drink and replacing the coldie with a warmie.

The fridge was set up to cool to 4 degrees.
12 volt battery system.

The results ranged dramatically:
On the Gold Coast Winter day, around 24 degrees in the day and cool at night, with the fridge full and cold and not opened I measured a power consumption of just 16 amps. About .66 amp per hour average.

In contrast, on the hot, humid Summer day with the fridge being used, the power consumption leapt to a massive 66 amps. About 2.75 amps, more than 4 X that of the Winter extreme.

I guess the moral of the story is that you need:
1. Good insulation on your fridge.
2. A decent battery bank to run it effectively.
3. An effective means of replacing the power.

Isotherm ASU 3201
Max volume 125L
Dimensions 270x160x155
Average consumptoin 0.4 A/h
Compressor: BD35F 300 x 60 x 210

Isotherm ASU 3701
Max volume 200
Dimensions 315 x 160 x 155
Average consumption 0.65 A/h
BD50F 355 x 60 x 280

12-24 volt power sensing refrigeration unit, suitable for mounting in new or existing cool boxes where battery power is at a premium. The ASU (Automatic Start Up) system senses when surplus power is available, during engine running, alternative power or genset operation etc, and speeds up the fan cooled compressor to rapidly freeze the eutectic type holding plate. As available power decreases, the ASU reduces power consumption accordingly. Low voltage cut-off and radio interference suppression are fitted as standard. Compressor unit comes complete with a fast fit mounting bracket for either vertical or horizontal mounting and three metres of pre-gassed tinned copper piping, incorporating re-openable quick-fit connectors. The stainless steel holding plate, with an average holding temperature of minus 9ºC, can be mounted at any angle high up in the cool box. Utilises R134A ozone friendly refrigeration gas. Suitable for use with the 381902 AC/DC converter.

1) Running engine for 1/2 to 1 1/2 hours daily reduces current consumption by 50-90%.
2) Reduce recommended box volume by 10-20% for tropical conditions
Extension Hoses, AC to DC Converter.

Sizes "L" and "O"
'L' 400x170x210
'O' small 210x240x95
'O' medium 230x320x100
'O' large 270x380x140

Isotherm evaporator plates, complete with two metres of pipe and re-openable quick-fit connectors are supplied as replacement parts. Although they are factory pre-gassed, the complete system must be evacuated and recharged with ozone friendly R134A refrigerant upon replacement. The evaporators are made of malleable aluminium, enabling them to be carefully shaped to suit virtually any cooler box configuration.

Sizes - Flat

Flat 350x130
Flat 815x210
Flat 1000x270
Flat 1200x190
Flat 1370x300


Optional Freezer thermostat.

If you want your fridge to operate primarily as a freezer rather than a fridge, you may wnat one of these.

Will replace standard thermostat for all evaporator plate type units.

The standard thermostat will cut in at between 5.5 and -1 and cut out at betwen -5 and -11.
The freezer thermostat has the same top end range but can go do to between -13.5 and -25 degrees.

Spill Over Valve:

This damper control valve is thermostatically controlled to open on demand and allow cold air from the freezer compartment to "spill over" onto the refrigerator section. No other parts or wiring is needed as the control is actuated by the temperature probe supplied. Allows the adjacent refrigeration section to the freezer to be fed cold air without the need for an extra evaporator plate.

Precision Wind Technology.
Ph:  02-6679 1234
Fax: 02-6679 1634
Mobile: 0427-734 026

Last update 2nd October 2014