Advantage OACS Series Central Chillers

Power and process piping only. OACS units ship fully charged and tested, ready to set on an outdoor pad, so there's no mechanical room, no cooling tower and no plant-water connection to plan for. What remains is mostly civil work: a level concrete pad rated for the operating weight, clearance around the cabinet, and supply and return lines from the building to the pad. Those outdoor lines are what gets underestimated - they need insulation against heat gain and sweating, and glycol if they can see freezing weather. Siting the pad as close as clearances allow shortens that run.

Dual-zone, when two process loops genuinely need independent temperature setpoints running at the same time. If only one temperature is needed, or the two loops don't run concurrently, a single-zone unit (or two independent single-zone units) is usually simpler to size and maintain. A typical dual-zone case is molds wanting 50°F alongside a glycol loop near 30°F. Serving both from one 30°F single-zone unit means tempering the warm loop back up and running the whole load at the colder, lower-capacity evaporator condition.

It is the only OACS built differently inside. It uses a rotary Screw compressor, a shell-and-tube evaporator and a stainless-steel reservoir on R-513A refrigerant, versus the brazed-plate evaporator, polyethylene reservoir and R-454B used across every smaller OACS model. Plan its maintenance and spare parts separately from the rest of the line. On a site already running several smaller OACS units, that means a second refrigerant to stock and recover and a different set of compressor and evaporator parts. With a load near the top of the range, ask us to compare it against two smaller dual-zone frames before choosing.

Read the letter after the tonnage in the model number. Single-zone (S-suffix) models use the OACS-MG manual; dual-zone (D-suffix) models use a separate OACS dual-zone manual. The correct manual differs by configuration, not by tonnage, so check the PN page for your exact model. The split follows the controls - dual-zone frames run the MZC multizone controller - so menus, alarm lists and communication setup differ between the two books. A plant with one S unit and one D unit of similar size needs both documents on file.

At least 4 ft on every side of a single-zone unit, and nothing overhead at all. Units placed side by side need 8 ft between them; end to end, 4 ft. If the unit sits in a pit or is walled in, the condenser top has to sit level with or higher than the top of the pit, with 8 ft to the pit walls. Screening fences or louvers need at least 80% free area and 4 ft of clearance, and be no taller than the unit itself; the pad itself is level concrete rated for the operating weight. Crowd it and it re-breathes its own discharge, pushing entering air past the 95°F rating on a summer afternoon.

More often than an indoor chiller does, because the loop itself lives outdoors. Advantage requires a water and inhibited propylene glycol mix whenever the setpoint is below 48°F or the unit could see ambient temperatures under 35°F. Mix it to protect to the lowest expected ambient or 25°F below the lowest setpoint, whichever calls for more glycol: a 45°F setpoint in a climate that reaches -10°F is mixed for -10°F, not 20°F. Verify the mix with a refractometer, and leave the optional automatic water make-up disconnected wherever it freezes, since it would dilute the glycol. On the refrigerant side, EC fan speed control and pressure-staged fans hold head pressure down to -20°F ambient.

The model number spells it out. 1P is a single process pump, 2P adds an evaporator recirculation pump, 3P adds a standby pump, and APT means no integral tank or pumps, for sites that already have a reservoir on a seperate station. Process pumps are sized at 2.4 GPM per ton nominal, so a 40-ton unit moves about 96 GPM - a 10°F rise at full load. Single-circuit units use Advantage's MG instrument; dual-circuit units use the MZC III, with a zone board per circuit. Both include Modbus RTU or SPI, with Modbus TCP optional. Other options: overhead drain-back prevention, supply and return isolation valves, an automatic low flow bypass valve and a main disconnect.