The past week has seen the new Marine Air system working in a heat wave, with Wind Horse devoid of awnings or even hatch covers: a worst case scenario for sure.
Our previous Marine Air system consisted of a pair of 16,000 BTU self-contained compressors for the great room, a 12,000 BTU unit for the owner’s suite, and a 10,000 BTU unit split between the aft staterooms. We knew this would require awnings to cool properly in really hot environments. We were willing to accept this in return for compressor sizes that would work with our inverters under way, and could be used with an eight kW genset. These were all functioning seven years later, but in the present conditions would barely have kept up with the heat.
We changed to test out a new, quieter, and theoretically more efficient generation of air conditioning gear. The quiet we had already experienced on a friend’s yacht, but the efficiency claims left us dubious.
Ed Todd, the OEM sales manager at Marine Air told us we could expect 20 to 25% better results. As SetSail readers know, the compressor condensers are now cooled using the aft fresh water tank, eliminating the risks associated with salt water leaks flooding the boat, thereby increasing pump and condenser life. The condenser cooling is also, in theory, a touch less efficient as heat transfer has to happen twice, the second being the fresh to salt transfer via the aluminum hull.
We are currently experiencing a heat wave: temperatures in the high 90s (F) with high humidity. With no awnings set and hatch covers off, allowing a substantial heat load through the large deck hatches, we can keep Wind Horse in the mid 70s (F) with ease, something that was not possible before without awnings. Even more surprising is the recovery period from hot, with the system turned off, to cool once the system is on. With the system off, again no awnings, early afternoon saw the great room temperature at 107F. An hour later it was down to a tolerable 85F. Bottom line, this gear is a vast improvement over the previous generation.
The Marine Air soft starts on the compressors do seem to reduce initial starting loads with the inverters and genset.
We should also report that the twenty gallon (80L) per minute Oberdorfer cooling pump was still functioning after seven years. It has been replaced with its spare. We think seven years of intermittent service in salt water is extraordinary.