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AC Water line flushing

Posted: November 16th, 2025, 1:43 pm
by 650Guy
I am going to guess, if you are reading this, you have had to flush your AC water lines at least once in you boats life. My home Port is in Lake Erie near Sandusky OH and am here to tell you myself and my fellow Carver neighbor have to flush our AC lines at least 2 times a summer as it clogs up with silt from the water. So much so that to make things easier for myself, i have installed quick connect flush ports on the manifold to make things quicker and easer for me. All while our other neighboring boaters with different manufactured boats (Cruiser, Sea Ray, Meridian) never have an issue... like EVER.

So my question to the brilliant group. Has anyone found a fix to this ongoing issue. No other manufacturer seems to have this issue as bad as Carver owners do. I have to assume its 1 of 3 things:

1) the water lines they use allow buildup and other manufactures use a different water line. (I believe this is unlikely)

2) the routing of the water lines have too many bends and those big turns allow buildup.

3) they try to save money by installing 1 pump for 3 systems and between the manifold and distances they have to go, they simply cannot get enough flow/pressure to keep the lines clear.

I would love to get all of your thoughts. My carver 396 runs:

1 1000gph pump
1 6000btu unit (Fwd)
1 16000BTU unit (Mid)
1 9000 BTU unit (Aft)

The mid and aft are the most common issues with blockages.

Re: AC Water line flushing

Posted: November 18th, 2025, 10:37 am
by KyleR
I have a 396 also and have only run into this problem once in the last 3+ years we have lived aboard. It was when we spent a few weeks in a marina in south Florida (summer time) to go visit family. The silt buildup in the A/C strainer was quite ridiculous as well as crazy growth on the bottom of the boat.

It only affected our aft unit but you could visibly see the water exiting the boat (for the aft unit only) had turned into nothing more than a trickle. I didn't notice the flow because we were gone so much, so my first indication was when we got back to the boat and the aft unit kept tripping off on high pressure. The flow from the other units appeared normal.

I pulled the lines to the unit and connected the shore water supply and flushed the unit - then back flushed as well. That seemed to restore everything.

I tend to agree with your #2 and #3 assessments. Unfortunately I can't confirm anything, but this has been my experience. Interestingly, we typically are moving most of the time and have never had this experience. Only when we sat for those weeks.

Kyle

Re: AC Water line flushing

Posted: November 18th, 2025, 11:00 am
by 650Guy
That is interesting! I run mine about 60-70hrs a year but she sits for a week, then run for 3-4 days, then sits for a week.

I always run my AC though. I often think, I’m running 3, $2000+ ac units constantly to save 1, $800 fridg. I’m not sure how smart I really am.

But I have to flush those lines at least twice a season.