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396 a/c discharge problem?

Posted: July 7th, 2020, 1:03 pm
by paulmadore
I've been chasing an issue with water in my bilge that seems to point to my a/c units. In troubleshooting this problem I decided to verify the purpose of all of my above-waterline thru hull fittings (fittings shown in owners manual don't match actual). When I run my a/c units (separately), all three discharge water through the same three fittings. The three locations are port side forward, port side aft, and starboard side aft. Additionally, my aft shower sump also discharges through the same starboard location.

Hoping there's someone with a theory on how this can be.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 1:30 pm
by Midnightsun
I do not think that would be possible. Reason I say this is, you would need in-line check valves and the danger of sinking the boat if a check valve would fail is very likely. I say check again, you must have seen wrong.

As for the AC condensate, this should run into the shower sump and get pumped overboard when the float activates the pump. I have a feeling the problem lies there as this is a rather problematic area. The shower sump should be cleaned out annually at least, not just a peek in the box and call it a day.

Welcome to the forum by the way.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 1:54 pm
by paulmadore
Thanks Hans. I've sorted out the sump and it's not going out where I thought. I'm going to keep chasing the a/c discharge.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:26 pm
by bud37
paulmadore wrote:Source of the post I've been chasing an issue with water in my bilge that seems to point to my a/c units. In troubleshooting this problem I decided to verify the purpose of all of my above-waterline thru hull fittings (fittings shown in owners manual don't match actual). When I run my a/c units (separately), all three discharge water through the same three fittings. The three locations are port side forward, port side aft, and starboard side aft. Additionally, my aft shower sump also discharges through the same starboard location.

Hoping there's someone with a theory on how this can be.


Welcome to the forum......have a real good look where the ac unit condensate drains go.....in our boat it goes out it's own thru hull but this boat only has one unit.......could just be a hose has a split from the winter or a loose clamp/ fitting.

All three of those units will use the one common raw water cooling pump, is my guess.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:38 pm
by bud37
I looked at your boats parts schematics and it show on there the condensate drains are split between the forward sump and the aft sump.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:44 pm
by Midnightsun
bud37 wrote:Source of the post I looked at your boats parts schematics and it show on there the condensate drains are split between the forward sump and the aft sump.


Thats like mine, the main and aft cabin AC condensates run into the aft shower sump and the forward AC condensate runs into the forward shower sump.

Just so there is no confusion. The condensate is just that, dripping water from the AC that ends up in the AC pan and then gets directed overboard, a shower sump or sometimes just into the bilge. Then there is the AC circulation pump which draws water from the lake/ocean and runs it through the AC and then back out again. In a multi AC configuration this is normally 1 pump supplying water to all units.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:50 pm
by paulmadore
I have one pump that feeds all three units through a manifold (I'd attach a photo of my technical skills permitted). Is it possible that when one ac unit comes on and calls for water, I have water going through all three whether they are turned on or not? This would explain water discharge through all three hull fittings regardless which unit is turned on.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:50 pm
by paulmadore
My condensates are plumbed as you have indicated.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 2:54 pm
by Midnightsun
paulmadore wrote:Source of the post I have one pump that feeds all three units through a manifold (I'd attach a photo of my technical skills permitted). Is it possible that when one ac unit comes on and calls for water, I have water going through all three whether they are turned on or not? This would explain water discharge through all three hull fittings regardless which unit is turned on.


Yep, this is how it works.

Re: 396 a/c discharge problem?

Posted: July 7th, 2020, 5:22 pm
by mjk1040
The AC drip pan drains could very well be plugged. I just disconnect mine at the shower sump and sucked them out with the shop vac. Pan was over flowing into the bilge. If you bilge water looks clean, your hot water tank relief valve or drain valve could be leaking and that drains into the bilge.