What to check on a Marine Chiller.
A chiller is a central refrigeration package that cools water, or a water-glycol mix, instead of cooling air directly. That chilled water is then piped to air handling units and cabin fan coil units throughout the accommodation and machinery control spaces. The alternative, direct expansion split units in every space, avoids chilled water distribution piping but multiplies the number of compressors, refrigerant circuits and potential leak points across the ship. Larger vessels with substantial accommodation blocks or significant control-room cooling loads generally favour a chiller plant; smaller vessels often stay…
What sets a marine chiller apart
A chiller is a central refrigeration package that cools water, or a water-glycol mix, instead of cooling air directly. That chilled water is then piped to air handling units and cabin fan coil units throughout the accommodation and machinery control spaces. The alternative, direct expansion split units in every space, avoids chilled water distribution piping but multiplies the number of compressors, refrigerant circuits and potential leak points across the ship. Larger vessels with substantial accommodation blocks or significant control-room cooling loads generally favour a chiller plant; smaller vessels often stay with DX splits simply because the piping run does not justify itself.
Main components
Compressor
Screw or scroll compressors dominate marine chiller plants in the common tonnage range; screw compressors handle larger loads and tolerate the part-load cycling typical of accommodation cooling better than reciprocating types.
Evaporator and condenser
Shell-and-tube heat exchangers are standard: the evaporator chills the fresh water or glycol loop, the condenser rejects heat to seawater. Seawater-cooled condensers need regular tube cleaning against marine fouling.
Chilled water pumps and distribution
Circulate the chilled water loop to air handling units and fan coils; most plants run duty/standby pump pairs so a single pump failure does not shut down accommodation cooling.
Refrigerant and controls
Modern installations use R-134a, R-407C or R-513A depending on build date and refrigerant phase-out schedules; older tonnage may still run R-22 under grandfathered rules pending conversion.
Selection / Sizing
| Parameter | What it drives |
|---|---|
| Accommodation and control room heat load | Sets total chiller capacity in kW or tons of refrigeration |
| Design ambient and seawater temperature | A plant sized for Baltic service will not hold setpoint in the Arabian Gulf without margin built in |
| Redundancy requirement | Many owners specify two chillers at roughly 60-70 percent capacity each rather than one unit at 100 percent, so a single failure still leaves partial cooling |
| Refrigerant type | Driven by phase-out schedules under the Montreal Protocol and the ship's trading pattern |
Regulations / Class
There is no SOLAS chapter dedicated to accommodation air conditioning, but class rules require adequate ventilation and cooling of control spaces where electronic equipment could otherwise overheat, and the Montreal Protocol governs which refrigerants may be used and phased in or out. MARPOL Annex VI addresses ozone-depleting substances and requires a record of refrigerant charge and any releases in the ship's ozone-depleting substances record book.
Typical faults
- Seawater condenser tubes fouled with marine growth — head pressure climbs, the compressor trips on high pressure, and cooling capacity drops well before the trip actually occurs.
- Refrigerant undercharge from a slow leak — capacity falls gradually, often blamed on ambient conditions rather than the actual leak.
- Chilled water pump seal failure — slow water loss into the bilge that goes unnoticed until the expansion tank runs low and the plant starts short-cycling.
- Duty/standby pump changeover switch left on manual — a pump failure takes down accommodation cooling entirely instead of triggering the standby.
What to look for in a supplier
- Sizing calculation based on your vessel's actual heat load and trading pattern, not a generic tonnage figure.
- Refrigerant choice compatible with your flag state's current Montreal Protocol phase-out schedule.
- Duty/standby configuration as standard on plants serving control rooms, not offered only as an upgrade.
- Spare parts availability for the specific compressor model, since screw compressor rebuilds are not something every port can handle.
Log condenser inlet and outlet seawater temperature at every watch — a slowly climbing differential is the earliest warning of tube fouling, well before the compressor trips on high head pressure.