Superyacht air conditioning: A guide to chilled water maintenance
Written by Simon Osborne
Chilled water air conditioning systems are the recommended choice for larger yachts and superyachts, and maintenance is important to extending any air conditioning system’s lifespan. A well maintained chilled water system can eliminate the need for emergency repairs, avoid breaking the warranty and ensure the crew, owners and guests go minimal time without air conditioning.
Air conditioner maintenance
Maintaining a chilled-water system isn’t much different than a direct-expansion system, except that there’s more plumbing. Reading the manual before starting work or contacting an expert is also important. But, if you’re looking for some helpful advice, see below some advice on fixing common problems which may occur.
Importance of a maintenance log book
It’s important to keep track of any maintenance you perform on board for your air conditioning system; this will help as this data can be very helpful when troubleshooting other problems later on. Keep track of the what, where, who, when and why for every maintenance task performed – then you’ll know exactly what work has been performed if more serious problems arise.
Check the seawater strainer daily and remove any debris; the pump needs to receive a good amount of seawater. If you are in waters where jellyfish or other debris is particularly a problem, you may find it necessary to add a strainer on the outside of the through-hull fitting.
Don’t run the seawater pump (at all) while the strainer is removed. If the seawater pump sucks up a shell or other debris, it can lodge in the condenser and possibly cause it to fail.
It is important to check the air filters at least once a month as dirty filters will reduce airflow and capacity. Some manuals will tell you to clean it and some will recommend replacing the filters. Your safest bet is to replace the filter if it is dirty or damaged.
Run the system
Systems should be operated on a regular basis. If the yacht is not in use, you should ensure the chillers and air handlers are cycled on 30 minutes to an hour every month.
It’s also a good idea to cycle systems in their reverse mode (cool to heat and heat to cool). Most units are reverse-cycle, meaning they have a reversing valve within them that needs to be energized periodically to keep all of the parts moving properly. This helps to maintain pump seals and internal mechanical contacts, while reducing the fouling effect of marine growth in the seawater circuit.
Check system water pressure
Check the pressure at the inlet to the pump while the water is cold (45-60°F), the chillers are off, and the circulation pump is running. For most boats, the return pressure should be 12-20 psig. If the system pressure has dropped below that, then more water needs to be added. Do not overfill as the expansion tank will not work properly.
If the system pressure drops frequently, then there is probably a leak, which should be located and fixed. Check all air handler and chiller bleed valves for leaks and tighten as needed.
Check the air handler and chiller condensate drains for obstructions by pouring two pints (a quarter of a gallon) of water into the condensate pan. If it doesn’t drain completely within 30 seconds, check the drain outlets for clogging. Remember some systems may have two drains.
Electrical connections should be inspected and tightened as needed. Heat and vibration can cause connectors to loosen, triggering poor contact and voltage drop or arcing. This can cause components to operate poorly, nuisance trip or prematurely fail.
Remove oil, dust, dirt, water and chemicals from the exterior of the motor and pump. Any signs of corrosion should be addressed immediately.
To protect against freezing due to inactivity in cold weather, remove the water, treat the water with propylene glycol, or combine these methods. Propylene glycol is usually the easiest and most practical. Often, improper winterisation can be the cause of an invalid warranty. Check your manufacturer’s manual for specific instructions.
Find companies specialising in yacht air conditioning.