AC Pump Trips Main Breaker

Oberdorfer pump makes their own bronze assemblies. The electric motor is the flavor of the month brand (GE, Century, Dayton, etc).
These electric motors are all usually open 56J, air cooled frames. Life span is subject to the environment.
You can see in this pump's installation (post #2), it it amazing it lasted this long, IMO.
But I have witnessed way worse.

Then, the pump's issues; as all brands do, the metal impeller and body wears away and the mechanical shaft seal will leak without warning.
Again, the environment; more silt-shorter life.

They should last much longer than a couple of years but when they fail it s usually not the motor but the head and the problem is either galvanic corrosion or erosion.

I was told that accelerated erosion is usually caused undersized hoses causing cavitation.

It s not just Oberdorfers (or the cruisair labeled Os) but pretty much any pump with bronze impeller and housing. Any of these will eventually erode resulting in weaker flow or pin holes in the housing. I v head this happen on a bigger Scott pump a few years ago.

Personally I prefer March pumps. The plastic wet head last much longer and are easy to swap. And leaks thanks to the magnetic drive.

Your air conditioning raw water pump is 30 years old??? I find that extremely hard to believe, because I've replaced plenty of them in Italian yachts too. They all seem to last 2-3 years. Usually the impellor and bronze body of the pump get eaten away from erosion. Generally I'd say our a/c raw water pumps run about 70% of the time during the day here and maybe 40% during the night on average. Some run close to 100% of the time during the day on the hotter months.

180 to 200 GPH per ton of AC (12Kbtu)

I make my own using Nylon 3/4" Ts and 90s. Nylon or Marlon 3/4" male pipe to 5/8" hose barb.
Grey short pipe nipples and reducer/adapter from the pump.
Lots of teflon tape. Just snug to not leak, not over tightened.
Keep it composite and never worry about it again.

These guys have excellent prices on March pump

. https://flagshipmarine.com/pumps/

March's are a special breed, they are magnetic drive with plastic parts inside the pump. The Scott pump and similar use a bronze body with bronze impeller. Erosion and Galvanic corrosion generally take them out in 2-3 years of saltwater use.

OP- I don't think March makes a pump big enough for 3 units. That being said, the synthetic march style that is big enough, made in Brasil, I cannot remember the manufacturer of, are junk, we have to warranty 1 or the 2 out every 8 months on a boat they were installed on. If your origional A/C pump was installed in 2012, I'd be inclined to install the same one. I'd guess though it lived in the closet as a spair for many years and they installed it a few years ago.

I ve been using a 1620 gph TE-5.5C-MD For 5 years now for my two 36k chillers. It runs 24/7/365

I have bought a 3100 GPH TE-7P-MD Which we re going to install on the 110 this winter to replace one of the Scotts which are about 4 or 5 years old. We run the chillers on one pump with the second one on stand by. March has even bigger models

There's no flybridge a/c? What does the origional pump flow? I would replace it with the exact same pump, since you stated access is a bear. Which means retrofitting another pump with a different mounting pattern will be an even bigger pain in the rear.

It won't be enough. You're not accounting for head pressure. Using a pump that flows 40% less volume is not going to work. What'll happen is if there's any scaling in the lines at all, you'll get units kicking off on high pressure. Cabo was very good at engineering things.

Lets see; all 3 condensing stations are there in the picture?
Top condensing station raw water inlet 5 feet max over the hull water inlet?

Pulse a few bends in the hose and fittings, lets guess the pump is pushing a 6 foot head.
You require approx 700 GPH for 44Kbtu.

The LC-5C-MD will push 840 GPH at 6 feet, 715 GPH at 12 feet.

IMO, good choice.

I would further say, your previous pump was moving to much water and not letting the condensing coils work to well.
Just the 104M is a common and more readily stocked (cost reduced?) model.
I have 3 of them on my boat.
Yes, I am over pumping but their cheap to me.

I would like to ad more thoughts; Mount the manifold high if you can and install a hose bib for a 4th outlet there.
The higher the manifold helps ensure the 3 ACs get a lil more even flow instead of the top one possibly getting less.
There is some name for this that escapes me at the moment, I did find this picture;

Or, install all three hoses up to the same height, then town to their own condensing station.
Just imagine the same weight of water to each unit.

The hose bib makes a great bleed and test valve and a good connect for back flushing.

Oh Yea, I luv spending O P M.

Good advice. I also like having shut down valves on each so I can backflush or descale each unit separately if needed

Flagship is great. I got my chillers and air handlers from them 5 years ago. Very helpful to answer any questions during installation. I ve also gotten 5 replacement air handlers for the 110 in the last couple of years.