A/C Condensate Drain

May 22, 2017
Catalina 310 Lake Carlyle
Most likely an old topic but my A/C unit is located in the port lazarette and the condensate drain empties into the bilge. (which is terrible) I'm thinking of running it to the head sink drain maintaining a downward slope. "T " ing it above the water line.
I know I will have to leave the head sink thru hull open for awhile when A/C is shut off for residual draining.
Has anyone done this?
Hull #17
No Tippy
Lake Carlyle, Ill.
Mar 26, 2011
Corsair F-24 MK I Deale, MD
Is the rim of the sink above the drain pan? The sink may drain into the AC unit.
Jun 21, 2004
Beneteau 343 Slidell, LA
Yes. I installed a “T” in my head sink a few years ago to handle condensate from an air handler in the lazerrete. The drain line from air handler to the “T” has a short run and a 2 foot drop. The thru hull fitting is located slightly above the waterline; therefore, I have no concern about leaving the thru hull valve open. It was the easiest and least expensive solution for me to eliminate condensate in the bilge.
May 22, 2017
Catalina 310 Lake Carlyle
Great. Good to know. I believe I have a 2 foot drop too. I can't see the thru hull from the side of boat so I think it is just below the water line. I'll make sure I "T" it in above the water line. Should be plenty of drop.
Then I have a big job to clean bilge.
Jul 12, 2011
Catalina 36 1771 Ft Pierce, Florida
The sink drain is a good idea, if the heights work out well and you don't drain your sink into your condensate pan. Another model is installing a venturi pump on the cooling line so that the flow of cooling water drains the condensate pan. Here's an example at Defender - https://www.defender.com/product3.jsp?path=-1|6880|2061076|2061077|2061085&id=2756613. The venturi pump is a simple no-moving-parts fitting that will work on any flowing water, and costs about $10 for a small plastic one. I guess the reason that Marvair can command $165 for their kit is that it comes with all the tubing, clamps, and check valves assembled for you.


Oct 5, 2004
Hunter 420 Passage San Diego
Got SUMP PUMP? I ran mine to the shower sump box. Easy button.


Feb 11, 2017
J/Boat J/160 Annapolis
Where does the shower drain lead to? Is it a "manual" switch on the shower sump or does it simply drain in the bilge or...?

If your AC unit is 'so high', could you simply drain it to discharge out the stern?