Adding A/Cond Elec Requirements

[frankv1205]

I plan to add Air Cond (16,000 BTU) to my 30 yr old 37 ft sailboat
I have the standard 12v Dc and 120v Ac panel (shore power)
Since I never use my water heater I thought I would use that circuit Or should I put in another 120 v sub panel I currently run a portable A/C unit off my 120v outlet that works but it is not that efficient
What electrical requirements should I be aware of?

[boatbod]

You can probably use a single 30A shore supply unless you have a large inverter/charger that is going to pull lots of power of its own. 16kbtu a/c probably pulls about 25A at startup (momentarily much more) then settles down around 16A when running.

[frankv1205]

Thanks Would the 16A also include the seawater pump?

[sdowney717]

15 amps will work ok sort of, my 16k btu heat pump draws 12.5 (14 amps max) and my water pump is under an amp, but I use a dishwasher drain pump not a real Marsh pump.
My circuit is wired up with 12 gauge wire, you want that because of voltage drop issues, and why push the limit. You circuit protect the wire, so that means use a 20 amp breaker.
I also have a Square D breaker panel with a combo GFCI-AFCI modern breaker for the heat pump, solves any issues with getting electrocuted, if possible.

You want the 20 amp circuit because when the compressor starts up, a 20 amp source is just better at starting the motor than a 15 amp source.

The compressor could draw 60 amps when turned on, the FLA or full load amps rating on the plate is for continuous running that you do NOT want to exceed, the LRA locked rotor amps for cold startup, but its a momentary very fast load, and a 30 amp shore cable can do that no problem.

[sailorboy1]

Originally Posted by frankv1205

Thanks Would the 16A also include the seawater pump?

it should, my 16K unit with the water pump uses 13amp and can run off my Honda (wirthan easy start added to the AC)

Don't cheap out with the electrical. Putting the correct breakers etc in are a small cost in the big picture of the project.