Our yachts are designed to not require air conditioning at anchor. With just a few knots of breeze, the combination of hatches, vents, and awnings promotes good air flow. But at sea with water flying, if the wind quits, the bugs are hungry, or tied to a dock, a good air conditioning system is a blessing.
Over the years we have installed all sorts of systems. Everything from massive water chillers with auxiliary boilers for heating, to single compressor pallet gear. And we have learned a few “secrets”, which will be employed on the FPB 64s.
The first is to install the gear where there is good access for inspection, changing filters, and service should it be required. With the FPB64 the compressor pallets are installed on the upper topside stiffener in the basement. Out of the way and with excellent access.
A major headache with air conditioning is draining the condensation. Many boats drain this to the bilge, or into a sump which has to be pumped. Another solution is to drain the condensation overboard. The problem is dealing with wave impacts that can flooding the catchment trays under the compressor units.
On the FPB 64 we are draining direct overboard using a specially designed system which employs a surge tube to eliminate the possibility of back flooding.
Almost all air conditioning and fridge units use salt water for cooling their condensers. The salt water is hard on pumps and heat exchangers, and introduces potential leak points into the boat. Many insurance claims for damage start with an air conditioning cooling system leak (which can cause a major flood very quickly).
The FPB 64s use a skin tank filled with fresh water for cooling fridges and air conditioners. No salt water, and nothing to admit outside water into the boat with a plumbing mishap.
You are looking at some of the plumbing for the air conditioners in the photo above. Each of the four air conditioners has its own cooling pump. This is a more costly to install than a single pump for all compressors, but is much more efficient and reliable. And if you leave the boat unattended with air conditioning on you don’t have to worry about floods!
Posted by Steve Dashew (June 21, 2009)
June 22nd, 2009 at 10:39 am
Interesting concept with the fresh water tank heat exchanger. Are you using demineralized water? When the boat is layed-up (winter season) are these tanks drained, or is anti-freeze glycol added?
Are there air-handlers involved, that one can alternate between fresh outside air or recirculated inside air?
Is the sytem designed to pull air from the respective room/area that it cools or from the basement?
Thanks for your insight.
Chris Locher
June 24th, 2009 at 10:03 am
Hi Chris:
Yes, demineralized fresh water. When laying up for the winter you have the choice of draining (all or partial depending on temperature) or using anti-freeze. The latter reduces heat transfer efficiency somewhat, which is why we prefer straight water.
The mixture of inside and outside air has to be done in a manner commensurate with heavy weather water tight integrity. So it is manual, using Dorade vents (adjustable flow) and/or hatches.
The various compressors draw from the basement, which is connected directly to the great room above and indirectly to the staterooms.