Marine Air Heat Pump Install

I spent 6 months considering all of the options and configurations that were available before I finally purchased and installed the system.  I did the whole installation myself and it went very smoothly.  I looked at Aqua Air (, Cruisair ( (located in my home town of Richmond, VA and recently acquired by Marine Air), Marine Air ( and Mermaid Air (  I considered both self-contained and split systems.

I choose a Marine Air Vector Compact 16,000 BTU reverse cycle unit that I purchased from Ocean Options (  This is not the same unit as the Marine Air Cabin Mate (a retail kit) sold through places like West Marine and Boat/US.  The components used for both are pretty much the same, but the orientation of discharges are different and the over all cubic inches of space required was less for the Vector Compact.  I ended up spending a little more going this route than using a Cabin Mate, but it suited my needs better.  The 16,000 BTU rating could be considered over kill for an IP31, but for the little bit extra in cost, I have a unit that can handle the hottest days and perform the initial cool down much quicker.

I installed the unit under my v-berth, with the air discharging to my port side (the IP31 layout is the reverse of the IP32).  From the unit I lead a 6 inch duct to a Y.  From the Y for the forward cabin, I lead a 4 inch duct to a discharge grill mounted through the side of the hanging locker.  From the other side of the Y for the main saloon, I lead a 6 inch duct to a discharge grill mounted in the side of the other hanging locker.  The return air for the unit flows through the two louvered doors that serviced the cabinet space under the v-berth.  It is best to have the shortest duct runs possible with the fewest angles.

For electrical service, I ran 10 gauge 3 conductor wire down the starboard side behind the deck/headliner flange.  I installed a dedicated 20 amp breaker at the nav station to service the unit.  For the control head I replaced the flat silver satin cable with a twisted pair cable as it runs parallel to the power cable for the entire length and did not want to have to worry about electrical interference.

My water intake is through a speed scoop/thru-hole I located in the bottom of the port side cabinet under the v-berth, the thru-hole for water discharge is just forward of this and located about 8 inches above the water line.  It is very important to take in to account the relative levels of each device.  I followed the mounting instructions provided at to the T.  The only deviation I did was to drain my condensate pan to the bilge.  This is not normally recommended as bilge vapors could get sucked through this and then discharged into the air via the unit.  I overcame this by running the discharge hose through a hole in the bottom of the locker.  The hole is the same size as the hose so provides a tight seal when inserted.  I then created a water trap (similar to what you would find under a standard sink) for the apor block.  Another option that Mermaid Air sells is passive device ( that connects to the discharge line that sucks out the condensate.  I will probably go back and retrofit one of these and see how well it does, but for now this setup works well.  I will also remove the unit this spring to paint the interior of the locker and may install some sound dampening material.  Other needs include installing longer tailpieces to the raw water fittings to allow for double clamping.

heat pump installed under v-berth

The center piece between the two access holes was removed.   The air discharges to the port side and runs through both of the hanging lockers.  The condensate discharges through a drilled to fit hole to the bilge.
closer view from above

Here you can see where a portion of the bulkhead between the two lockers was removed.  The shelf in the center locker was also removed.
through hole, sea-cock and strainer installed in port side cabinet below v-berth

A hole was drilled in the hull, a speed scoop installed from the out side and plywood backing on the inside, 3M 5200 was applied to both.
view from with-in cabinet

To the left of the photo you can see the sea water circulating pump.  It is installed on a small shelf secured just below the heat pump.
straight ahead view through center cabinet under v-berth

Here is a view showing the heat pump unit and the shelf installed for it.  To the right, the shelf sits on a block bolted to the bulk head.  To the left, the shelf sits on the top of the bulk head that I cut to the appropriate height.
main cabin hanging locker view

Here the air discharge for the main cabin enters from the right and discharges to the left just above the port side settee.  The discharge was is installed at the very top back of the locker allowing for normal usage of space.
v-berth hanging locker view

Air discharge enters bottom right, Y discharge splitter located in the middle, v-berth discharge located upper right and discharge to main cabin locker located in the upper left.
view from the front of the v-berth

You can see the small discharge grill located on the side of the hanging locker.  You can also see the sea-water discharge tube running to the right of the photo.
better view of the main air discharge and sea-water discharge tube