ASU Modular Refrigeration Units

ASU Automatic Start-Up Air-Cooled Modular Refrigeration Units

"Smart" Power Consumption Increases Cooling When Alternator Power Is Available • Use for Fridge or Freezer

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Isotherm ASU Automatic Start-Up systems are designed for installation in existing cool boxes, mainly in sailing yachts where battery power is at a premium. The microprocessor controlled ASU system dramatically reduces power consumption while supplying refrigeration in abundance.

The ASU circuitry senses when high levels of energy become available from the engine alternator, shore power, or even a solar panel installation, and speeds up the compressor to rapidly freeze the holding plate — which acts like a block of ice, storing the cold for long periods. This keeps the compressor from running when the engine is off, which saves battery power.
Once the stored cold is completely consumed (if the engine has not been run in the mean time) and the compressor is running on battery power alone, the ASU circuitry "sips" power by only running the compressor intermittantly, for short periods and at a slow speed - just enough to maintain the box temperature, without attempting to freeze the cold plate further.
With normal engine operation, the result is a significant 30 to 50% reduction in electrical consumption from your batteries!
These units provide refrigerator or freezer capability with temperatures down to 21°F (-7°C).

ASU Modular Refrigeration units come in three versions — air-cooled (with fan and condensing tubes), water-cooled "Magnum" (with an integral cooling water pump), and water-cooled SP (Self-Pumping - with a specially modified thru-hull fitting with a built-in condensing coil).
The models in this group are the air-cooled ones in which ambient air is circulated across the condenser by a fan — the traditional way to remove heat from compressed refrigerant. It is important that the compressor compartment is well ventilated, allowing cool air to enter from below and warm air to escape at the top.
See Related Products, below, for the other models of modular ASU units.

• Holding plate can be fitted at any suitable angle high up in the box
• Compressor is small enough to be fitted in stowage compartments within connecting distance from the holding plate
• Extremely quiet operation
• Controlled by special control panel
• Ice cube tray available
• Pre-charged and ready to go
• Easy installation; compressor snaps into pre-mounted base bracket; Quick Connect fittings can be connected and disconnected without loss of refrigerant
• Compressor can be mounted on horizontal or vertical surfaces
• Runs on 12V or 24V DC
• An optional Universal AC/DC kit for using both 12/24V DC and 115/230V AC at 50/60Hz is available; see Accessory Products, below

Refrigerator temperatures from 35°F to 45°F are proper refrigerator temperatures. Reduce the box volume by 10-20%, in tropical conditions. "Dual" rated units can operate either as a fridge or a freezer by setting the temperature with a special thermostat.

Heavy on the technical side...

How much power is needed?
This is the most frequently asked question of all.
Isotherm can give exact power consumption figures for their range of refrigerators, freezers and boxes, as they know their size and quality of insulation. It is more difficult to quote a figure for owner-installed refrigeration boxes as the exact size of the box, or even more important, the quality and thickness of the insulation material used is not known. The power consumption figures provided for a particular volume of cold compartment in our Specification Tables, are therefore calculated for a 12 volt unit, with insulation material of medium quality and thickness (approx. 2 inches), with an internal temperature of 42°F and an ambient temperature of 72°F. The average power consumption is given in Watts/24 hours.

Click here for a summary of features and specification data about ASU modular refrigeration systems.

Click here for an in-depth discussion of ASU technology and the various ASU Modular Refrigeration Systems available (see pages 56-74).

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