Chiller help

I wonder if "soft start" modules on the compressors would help.

I would have soft starts on every chiller boat, as you have the seawater pump kick on and the chiller startup usually at the same time. The soft start modules aren't that expensive to add to an existing chiller.....$700-1000 usually.

You really need to diagnose exactly what the real issue is before throwing 1000's of dollars at it. How long has it been since you descaled them? If they haven't been descaled in a long time, that will make them draw a lot more amps. Also, both chillers should not be kicking on at the same time, the startup temperatures should be about 2F apart. The boards are in the Dometic boxes in top right of the picture closer than the chillers. Loosen the screw, take cover off and there is a digital circuit board in there, this is where it displays error codes (HP/LP) etc. but also where you set the cut in/cut off pressures. Also, how long has it been since the generator has had both fuel filters changed as well as a tune up (valve adjustment etc.)? The first place I would start is putting a good clamp on amp meter on each chiller and getting it to cycle and seeing what startup amps it's pulling and what running amps each compressor is pulling. There should be a plate/sticker that will tell you what both "SHOULD" be. If 1 of the above mentioned items is not close to that you've found your problem. Next move onto the circulating pump and the sea water pump and test them. If all of those are close to rated amps, you really need to focus on the generator, check cycles and see what's going on with it. I agree with Pacal, if a generator isn't running correctly and gets a large load, rpm's drop too much, amps skyrocket and boom the breaker pops. If the chillers haven't been descaled in a year or so, I would do that too with the Trac fluid.

If I was replacing them, I'd go with dometic, 2 units, and larger if you can go to 36k btu's with soft start compressors. That way the entire boat should run on one chiller, but you also have to have a good a/c guy check the system and make sure that oversizing will not cause the 1 unit to short cycle because the air handlers aren't big enough to utilize it. Before doing this, you really need to add up all of the BTU's each air handler is. What boat is it in? My guess would be a Neptunus.

I wouldn't consider anything but a dometic. Period.

I ran a few boats with flagship. The technology was rudimentary at best. Well built, BUT the blowers were noisier than hell and a single speed. The staterooms sounded like you had a hair dryer on high, and whatever they were mounted on vibrated like hell.....woodwork.....bed....or closet...... Like they can't figure out how to put a simple rheostat on them and isolation mounts in 2019? The self contained units, the compressors were hard mounted to the pan, everything was hard mounted to the pan and it made the beds vibrate like nobody's business and noisy. The thermostats were household units that had no way of displaying any error codes of the units (high pressure/low pressure). Plus there is no service network So you're paying someone to learn the unit in order to fix it, then track down the parts. One boat I ran the Flagship marine units had high pressure switches on self contained a/c's that you had to manually push a button to reset them. And, each unit was a pain in the rear to get to. It also had thermostats that if the AAA battery went low in it, wouldn't turn the compressor on but the fan would run and no indication the battery was low. But the noise and vibration would be the main reason I wouldn't touch one. It's 1960's technology. Please tell me one yacht manufacturer that installs Flagship marine in their new yachts?

The dometics have titanium raw water loops so descaling the chillers doesn't degrade the raw water loop. They're quiet, they're well engineered, and the circuit board monitors the unit and displays the error codes. Plus easy peasy to install new units with existing plumbing. My guess is your repair is going to cost a lot less than replacing the units.

Frigomar I wouldn't touch because the Italian part and parts.

This sounds like typical factory stuff from some builders. While entirely possible it was done after the build, I highly doubt it. I once ran a new Italian 55' yacht that had the forward VIP air handler in the forward bilge, it simply had a return vent in the floor and no ductwork, the plastic waste holding tank was also in this semi sealed forward bilge!!!!!!!!!!!!!!!!!!!!!