AC/Heat

[sunvale1]

How does one go about determining the BTU rate on an AC/Heat system for a 36ft trawler. I understand to big a unit is not the best way to go. Does anyone have a write up on their install.
I had 2 AC specialist work on my 5 year old unit and it is ceased up needing to be replaced. Draws over 120 amp when I reset the breaker, that tells a story.
My AC/Heat looks like a nice little package and has pretty straight plumbing to replace. But non the less I would love to read or get some info from people that have done that job.

 

[CaptTom]

I assume you mean how many BTUs to size the system for.

That's going to depend on where, when and how you use the boat.

I installed two, 15,000 BTU units in my 36' trawler in the spring. Each draws about 10A when running, give or take. The boat has been in Northern New England all season. Here's what I've found:

- On a hot, sunny day (90 F and above) running both units will not quite cool it down to 70 F. But it does keep it much cooler and dryer than the outside, which is good enough.

- Cellular blinds on the saloon windows help a LOT. Keeping the sun out in summer is a big help. If you could shade the decks or put awnings on the windows, that would help a lot too. Likewise, leaving everything open on a sunny winter day warms the cabin nicely.

- It was 30 F last night. Both units running about 75-80% of the time kept it comfortable. I think much colder and they'd be running 100% of the time. There's no way I could use them as the sole heat source throughout a northern winter. But the water would be too cold for a heat pump anyway.

- Anywhere in between those extremes, I run just one unit at a time. Having two smaller units is much better than one large one.

- The location of the thermostat is critical. The temperature in one spot is not necessarily the same as other locations around the boat.

 

[sunvale1]

Thanks for the info. I had not considered dual units. Right now I have a seized AC single unit. The 16000 thus far it was sufficient to keep things cool during the Lake Michigan summers. The heating system was OK as well.

Going to have a look around and see if I have the room for a second smaller AC unit.

Will pull the old unit out, bench tested and see what I can repair. If it's done for, I'll install a new one in it's place