AquaAir Chiller Keeps faulting

First thought would be to crack open the sea chest while under way and note water flow, then repeat at rest looking for a large delta between both flow rates. If water flow is equal, should rule out any issues “outside” the system.

The faults you mentioned have very different causes. Low pressure is obviously just that but if you ve had the system serviced then they should have checked the pressures. Are both chillers showing low pressure ??

High pressure on the other hand is almost always a lack of water flow or dirty condensers. Can you observe the overboard discharge?

flow switch issues are just as unrelated since that’s an issue with the chilled water loop. Could be air in the loop or a circulation pump problem.

just find it odd that you re having all three unrelated faults at the same time.

One of the negatives of sea chest, when poorly designed, no top vents and water customers mounted on the top of the tower (ACs?), lots of foam gets pumped to the equipment.
For the old salts, I learned of these issues on a 44 alloy Striker many (MANY) moons ago.

Yep, all settled down while dockside.

That boat will never be cool over the summer, 10 tons isn't even remotely close to what a yacht that size needs.

You have 2 different brands of chillers?

That being said, if the water level is 8" below on that sea chest versus the other one, while the engine is running, the thru-hull isn't nearly big enough (or it's got a grate or barnacles inside the opening restricting waterflow) to feed both the engine and A/C and the engine sucks harder so it wins the battle.

Some yachts have a vent hose from the lid up really high in the air, it allows any air that gets sucked into the seachest to escape, without having to be sucked through the equipment to get out.......

Can you easily get to the discharge ? If so put in a tee and a couple of valves. Route one leg of the tee to a 5 gal pail. Flip the valves to divert discharge to pail. Time how long it takes to fill the pail at the dock and under way.

if the pump has salt outside it means it’s leaking. What kind of pump ? Oberdorfers and the likes have metal impellers which erode with time. How old is it? Start by replacing the pump and getting the old one rebuilt as a spare if even possible.

I agree with J. 10 tons isn’t enough to keep the boat cool during the day in summer time... at night you ll
be ok but not during the day. What is the loop temperature during the day and at night ?

Two different brands of chillers is a red flag as well... yea in theory the Ocean Breeze should get along with the AquaAie controls but who know... maybe that’s why you re having these contradictory errors

another concern is the raw water discharge being underwater with full tanks.

Skippy J got it.
In rough water or running bow high, our ole sea chests would fill with foam and air. The new saloon A/C would kick out with a high pressure trip.
Took a while to figure it out. Ran an experimental hose from a chest top cock to the ER air inlet drain box. That worked good and then the boat sold.

Never knew we were having sea chest issues until the ole 3 knob system was replaced. No error codes from a 3 knob panel.

While your running was what I was thinking.
Dockside by now the chest would be full. Outside, in the chop may have been different.

Check out Scott pumps. That’s what we had on the 84 and now the 116. Very good pumps both for the loop and sea water. I replaced the sea water pump 3 years ago as the impeller was eroded and had it rebuilt as a spare. Pretty sure it was original to the boat or 8 years old then

I prefer March but I don’t think they make them that big.

You might try contacting Tropical Marine Air Conditioning in Lauderdale, they were a large dealer for Aqua Air when they shut down. We bought some spare parts from them. If you are getting low flow on the loop it is probably air. You can program their air handlers to run continuous for four hours which is good for clearing any air in the loop if you have automatic air vents and bleed highest air handler. Easy to troubleshoot the low flow switch and replace if needed. Be careful with tech descaling the loop, it can cause leaks on the a/h copper plumbing connections. Also a reset to factory default can sometimes cure false readings. The new pump may fix the high pressure default. The CD100 pump is cast iron, the Scott pump Pascal recommended is a much better bronze pump.

I'm confused, in post #5 you stated that port water level is 8" lower than starboard seachest water level.

The other thing with vented seachest, is you know if the thru hull is restricted because the vent will allow it to suck the seachest water level down.

A/c pick ups should NEVER be on a sea chest.

absolutely replace the pump. See if you can plumb in a water pressure gauge after the pump. Watermaker companies use them and sell them. It will tell you exactly what's going on. See what the pressure is at the dock and see what the pressure is at cruise, will also tell you if the seacock is getting clogged.

I had a cd100 water pump that was rusting badly on my last boat with twin 4 ton Aqua Air chillers. Replaced with the Scott bronze pump with zero problems. Thinking the cd100 pump was Aqua Air's own part number. Check with Tropical Marine Air.
Thought I would pass on when the boat recently sold the new owner had a Electro Clean electro-chlorinator installed between the ac thru- hull and strainer. On start up the flow was 15 gpm, after 3 weeks the flow was 16 to 17 gpm, and now at 2 months reported at 17 to 18 gpm with no maintenance other than cleaning sea grass from the basket. Doubt it would work on the sea chest and not recommended for engine raw water use. Also claim it does not harm the cooper-nickel alloys. So, they do work and save continuous cleaning with corrosive chemicals. We lost both of our chillers because of previous aggressive cleaning with corrosive acid cleaners at considerable replacement cost. Makes the unit installed easily pay for initial cost in several years with reduced maintenance and a longer life. If you add a thru-hull for the chillers you might want to consider the Electro Clean, they apparently work well. J's suggestion to add a pressure gauge is a good idea for monitoring flow and maintenance needs.

I'm dealing with a yacht right now with a 1 year old electro clean system, while the a/c strainer doesn't seem to get much algae build up on it, it certainly is getting a lot of barnacles growing on it. So not thoroughly impressed over my own methods of using bromine tablets.