I took this drawing from the Hunter owner’s manual. It shows the layout of the factor installed AC. I used it as a general guide for my compressor, sea water pump and ducting locations.

Drawing of the factory installed AC option

I decided to share an existing thru hull with the new AC water intake. This allowed me to plumb the AC water with the boat in the water. The head intake was used and the hose was re-routed to the location shown in the picture.

For reference, you are looking at the space under the aft bunk on the starboard side of the boat. The cutout (already existing) in the bulkhead that the pump discharge hose disappears into is directly under the floor pan for the head.

The hose comes into this space from the existing thru hull and ball valve. This thru hull is located just aft of the engine and next to the shaft log. The original hose went from this thru hull directly to the head. The flow of water first goes through a sea strainer and then tee’s off to feed both the AC pump and the head. Both branches then go through check valves. The head branch then proceeds on to the head. The AC pump branch goes through a ball valve shut off and on to the pump intake. After exiting the pump it goes through a bleed off valve and then forward to the compressor unit mounted under the V berth.

It was somewhat challenging to route this hose all the way forward. I was able to keep it in the bilge as far as the forward bulkhead that separates the salon from the forward cabin. It followed the same path that the hot water lines use to go between the engine and the hot water tank. It was routed the rest of the way under the starboard settee and under the V berth bunks.

Sea water pump and plumbing

I went with a 12,000 BTU reverse cycle unit from Mermaid Marine Air. I wanted the largest unit possible because of my location in Florida. Mermaid recommended the 12000 if I wanted any hope of keeping the cabin cool during the hot mid day sun.

The size of the unit and the limited space for installation presented some challenges. The unit itself fit comfortably into the space forward of the fresh water tank, but the space needed for the supply air discharge fitting was a problem. I had to mount the unit with the air discharge facing forward and then wrap the two ducts around 180 degrees to be lead aft. This created some restrictions in the air flow, but so far it’s not causing a problem with freeze up yet.

12,000 BTU Mermaid Reverse Cycle AC unit

The port duct is a 6 inch that supplies air to the main cabin and also to the forward cabin. The Starboard duct originally was to supply air to the aft cabin only. The 6 inch duct reduced to a 4 inch duct midway there. After routing the duct, I discovered that I could branch off and install a second 4 inch duct in the main cabin under the starboard settee. This will be done as soon as the new parts arrive.

Close up of installed unit

This picture shows the tight duct routing around the fresh water tank on the starboard side. It also shows the mounting location of the electrical control box.

Starboard duct routing around water tank

One of the hardest jobs was cutting 6 inch holes through all the bulkheads to feed the duck through.

Port side duct routing

All of the ducting was hidden in the forward hanging locker. The main cabin supply vent was a 6 X 8 teak wedge vent that exits out the top of the hanging locker. The Forward cabin is supplied by a 3 inch branch that feeds back forward through the bulkhead. (See next photo)

Port side ducting and main cabin supply

The forward cabin supply vent can be rotated to direct air in any direction and also completely closed if needed.

Forward cabin supply vent location

The aft cabin supply vent is located on the starboard side just above the shelf. The routing of this line was difficult. The duct followed a path under the starboard settee where I encountered several interferences with existing hardware. These included the fresh water pump, the battery charger, the starting battery, and one of the house batteries. After exiting the settee, the duct went behind the electrical panel at the nav station, through the bulkhead into the head (behind and under the sink), and finally into the aft cabin.

Aft cabin supply vent

The return air vent is in the forward cabin at the base of the bunk. The only down side to this location is that the forward cabin door will have to remain open while the AC is running.

The unit is working great so far. There have not been enough hot days yet to really test it out.

Return Air Vent