Any marine AC experts here??

[madhatter1]

46 Hatteras. 3 AC units. Had some age related issues with the water pump control boards. Boat is 1982. Corrosion on fuse, burned wire, triac board needed replacing, etc. Anyway after multiple pump issues and this stuff the AC pump never seems to work when needed. AC guy had everything working. I am an AC controls guy so after ran each unit one by one making sure each had control of the pump. All good. Couple weeks later I turn the AC off in the boat earlier this week. Go to turn it back on and no water flow. Go down and pump is roasting hot and will not turn (March AC-5C-MD-115V 2 months old). Turned all breakers off to AC units and pump still has power. Another failure but unknown where at this point.

So being a controls guy I want to rip out the control boards and replace with RIB relays (2 110V coil and 1 240 coil) and parallel to switch 120vac to the pump with a contactor (magnetic motor starter). Only other option is an start/stop switch and I turn the pump on when I need it. Would rather circulate water even if not needed then go through anymore of this.

And Murpheys law always kicks in. Pump does not work either day I need it to or if it does work fails when engines are roasting hot.

Thoughts? Going batshit crazy!!

[Briankinley2004]

My pump is on its own breaker and runs all the time. I have 4 units and their on/off status has no bearing on the pump running. Most of the boats I have run or am familiar with (that have multiple units) are set up like this. As far as I can tell on my boat and my friends 60 that has a similar set up they came from Hatteras like this. I have friends with Post and a Viking that run 24/7.

If you want to keep as is thats cool. I would check the amperage draw when pump turns on. If it is high suspect a locked pump. If it is way lower than the rated running amps maybe you have a loose connections or corrosion.

[madhatter1]

Only draws less than 3 amps locked rotor. Not the issue. So larger boats turn on pump and run 24/7 when occupied? Much simpler solution.

May just bypass all that and put in a switch. Thanks.

[carolinacoast]

I went through a period like this. I now have 2 pumps , so I can valve over to a backup.
After I spent lots of $$ with 'local experts' in different areas, I finally started sending the cooked pumps to depco in clearwater.
lightbulb moment. They will break down your pump and tell you exactly what is going on. In that instance, on one pump, new like yours, was galvanic corrosion from a nearby boat with electricity in the water.
AC guys will just change the pump, again and again. Depco rebuilt it for 1/3.
I have modified my pump choices, and have had no problems in recent years. ceramic pump on monel shaft of an oberdorfer pump.
So now I have that as a primary, a backup, and an extra new motor from another pump that I sent them.

AC is a requirement where we are.

[Pascal]

I ve always has my pump run 24/7. Here in SoFl there is always at least one compressor running anyway so need to bother with a relay box

The March pumps are pretty much bullet proof. Weird that yours is burned up. Did it get wet? I once had one fail because of condensation drip on the motor

[carolinacoast]

Had one fail from a raw water/salr water manifold crack out of sight on bulkhead. caused a saltwater drip on the pump that cooked the pump in a short period.

[oceanjake]

Lots of pumps run 24/7. My boat has 6 a/c’s. All but one switch the pump on only when needed. The final AC kicks the water pump on the second you put it into Fan mode even though compressor is off. You won’t hurt anything by running it on it’s own breaker, but you will want a QUIET pump. I love my sealed koolair pump. Practically silent.

[oscarvan]

Only other option is an start/stop switch and I turn the pump on when I need it.

That would be my solution. In cooling season with three units there's always one on..... Let it pump.

[madhatter1]

It's fixed!!!

Bought a new pump but before changing it I bypassed controls and sent 120 direct to the pump. It works. Apparently when I last turned off the AC's it did stop pumping (which is what I thought because I always check)but the control board was feeding it something that would not turn it but made it very hot and hum. Never did read the voltage, just read the amps which was 3. But who cares what at this point went bad. I am going to run a switch up to salon and run 24/7 whenever I use AC as recommended.

Will keep the new pump on board for a while in case this on fails. Works now but no telling if there is long term damage from the under voltage that was fed to it for 3 or 4 days.

[Pascal]

Glad you got it working. The pump should have its own breaker, I use that to turn it on or off come winter when we may not need AC for a couple of days