For The Love of Water… and Marine Air Conditioners
If you love to be on a boat or yacht, then worry not about air conditioning option. Marine air conditioners are made available for you, should you need one.
Why marine air conditioners are important while you’re fishing, making a weekend getaway from land, or just feeling like being in your favourite aqua-transporter?
Because it will get unusually uncomfortable, be it during cold season, and especially during hot summer.
You’re exposed on an open space, with no radiant heat barrier. The only heat insulation you have, is your boat’s wall and windows.
Needless to mention, heat loss during winter will be high, and heat gain during summer will be very high.
It shares similar fate with automobiles, only slightly worse. Humidity in air can be very high due to proximity with water.These justify the need of air conditioning on a boat.
Suitable air conditioning units for marine have sizesfrom,
Spot cooling only – with 12 volt portable air conditioners, to
30,000 BTU/hr (or 2.4 ton or 7.8 kWh or 6 hp) – with chilled water systems
Marine air conditioners do not come with EER, or SEER rating, but you can compare efficiency between your choices, using simple formula specified in this page.
Design features:
We’ll begin with,
Specific marine air conditioners
One fundamental difference with common, land air conditioners – the cooling method of the condenser.
Condensers for common land air conditioners are cooled using air. However, air conditioning on water gives you an added advantage for condenser cooling. Water.
These air conditioners use water to cool condenser. Hence, a marine unit can be kept compact as it is more difficult to change temperature of water, compared to air
Corrosion is a huge threat for these units.
Therefore, manufacturers will provide these units with a special coating. Normally used coating is baked enamel, as an excellent corrosion barrier
Other parts will also be covered to prevent from water splash and chloride attacks.
Plastic covering is a commonly used material, and stainless steel parts will prolong parts’ life from corrosion
Condenser fan, is substituted by a water pump, to deliver water to cool the condenser
Condenser shape and type is also totally different from air cooled condensers.
Air cooled condensers are of tube and fin type, whereas marine air conditioner condensers are of tube heat exchanger.
These tubes will be wound into a coil shape
Chilled (or heated) water air conditioners are used for large conditioning applications.
Brine will be used as a secondary refrigerant. Chilled (or heated) water systems are essential in large scale air conditioning to minimise primary refrigerant quantity used, and to maintain good compressor lubrication
12 volt air conditioners operate using direct current derived from a generator, engine’s alternator or battery bank.
However, we have to bear in mind that air conditioners consume a lot of power. Hence we’ll need to size the power input such that, it will be enough for other electrical equipment
Properly sized ducts can be used with larger air conditioners, for central air conditioning.
Central air conditioning in marine application. Now that’s cool
Next,
Common air conditioners – used in marine application
The simplest one is the 12 volt portable air conditioner.
12 volt portable air conditioners available in market do not have any compressor.
These are equipped with a blower, and you have to fill in ice to cool air. So, 12 volt portable air conditioners can only cool a very small space, or used for spot cooling
Rooftop air conditioners are mounted on the… roof of your cabin.
However, this type of air conditioners are not only used in marine application. It can also be used in your residence or even your RV (recreational vehicle).
These marine compatible air conditioners come with corrosion resistant parts, and water proof cover when not in use.
Condenser part will be on the top side (outside) of the roof, and the evaporator on the bottom side (inside) of the roof.
The condenser is air cooled.
It’s like a window air conditioner, only not. It’s placed on a roof, and "umm" looks better
Portable rooftop marine air conditioners is an evolution to rooftop air conditioners.
However, this type of air conditioning unit will be useful, if you feel like being creative and use it for your land vehicle – normally on RVs
General design conditions
Voltage requirement for all marine air conditioners are similar to land air conditioners, except for 12 volt air conditioners
Marine air conditioners will usually come with heating option, either with a heating coil, or with heat pump option.
12 volt portable air conditioners do not have this option. But you can try to put in some hot water bags in the container and see the effect
Since generators and marine ACs can’t be separated, then a CO (carbon monoxide) detector is a must
Water discharge line for water cooled condensers must be placed, above the suction line.
Water suction line, suction filter and pump, must be placed below the water level
Service and maintenance:
Maintenance for marine air conditioning unit is similar for air cooled air conditioners.
Check out the details of air conditioning maintenance here.
However, there are some differences in the maintenance,
Water pump’s suction filter has to be kept clean
You will have to watch out for coating peel off, or degradation of the tube coating. It is also essential that the tubes are checked for leaks
Check for corrosion on other parts as well
Cover your air conditioner if you are not going to use it for a long period
Keep the water side tube of the condenser, clean and dry, if not used for a long period
Which one of marine air conditioners to choose?
Difficult choice? Worry not.
As a general guide, 12 volt portable marine air conditioners are for spot and budget cooling.
Other marine air conditioners can be used for space by space, or central cooling.
Just make sure that you have enough voltage supply and power for these.
