Maintaining Chilled Water Air-Conditioning Systems

1 November 2020 By Jack Robinson
illustration of air conditioner

Preparing the owner and guest staterooms for upcoming sea time can be a daunting task. Ensuring that the air-conditioning system is comfortable for the guests should rank among one of the most important tasks. A regular preventative maintenance inspection and function test to each stateroom’s chilled water air-conditioning system can easily avert most complaints.

1. Thermostat Calibration: One of the most common complaints is the stateroom’s temperature set point is either not being achieved or being reached too soon and prematurely shutting the fan coil’s water valve off from cooling mode. This can easily be avoided by checking and calibrating the system’s temperature sensor to the stateroom’s actual temperature through the programmable calibration feature on the A/C display controller. Calibration procedures can be found in the digital controller’s operation manual.

2. Drain Pans: Ensuring that drain pans are draining properly can prevent damage to flooring and other soft goods. Over time, drain pans and drain lines can become obstructed. An air handler’s drain pan can be easily checked by pouring a gallon of water into the drain pan and observing its ability to drain. If it drains poorly, using compressed air to blow out the line, which typically resolves the issue.

3. Air Filtration: Replacing air filters monthly, or at a minimum of once every two months, increases air flow, as well as the unit’s ability to cool or heat properly. This also removes airborne particles if a high-quality air filter is used.

4. Fan Speeds: Cycle the keypad through each of the fan speeds to ensure that there are no undesirable motor noises at a given speed. After confirming operation, set the fan speed to “automatic.” On most controllers, doing this will decrease the fan speed, as the staterooms’ temperature approaches the set point. This allows for less temperature swings and longer cooling cycles, which in cool mode can help reduce the relative humidity in the boat.

5. Auxiliary Heat: Many air handlers are equipped with auxiliary heat. Check this function several times throughout the year for proper operation because dust and debris can build up around the heating element. This can cause a burning smell on initial startup if the element has not been energized in a long time. If that cold day comes along with a boat full of guests, having those elements clean will come in handy.

6. Achieving Set-Point: Every person has their number in terms of desired temperature. It’s a good idea to be sure that each stateroom’s A/C system can reach at least a temperature of 70°F. It’s important to know that it may not be realistic for a chilled water system to reach an air temperature below 65°F.

This column originally ran in the November 2020 issue of Dockwalk.

Jack Robinson is the general manager at Elite Marine A/C. He started his career with the U.S. Navy in 1981 specializing in marine air conditioning.


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