Overboard water discharge

[FabioC]

I realize this is quite a dumb question, but I cannot quite figure it out by myself and I am bit embarrassed asking it to my neighbors at the marina... (so I ask it in an open forum...)

I notice that most powerboats (and some sailboats) docked at the marina have a small but continuous stream of water discharging overboard. They are not attached to the fresh water. I am guessing this stream comes from the heat exchanger and is circulating raw sea water. Is that correct? What I do not quite understand is why it is needed continuously. I see it also during the summer. Why is it needed when the air temperature is relatively high?

Thank you!

[smith8273]

This is also one of my wonders...

[thomm225]

It's probably from the Air Conditioner.

Usually the water only runs when the air conditioner is running.

[AndyEss]

Could be discharge from a water cooled refridgeration unit

[peghall]

Don't be embarrassed by the question...You're actually smarter than the "average bear." Most people jump the conclusion that bilge pumps are running full time on those boats and that owners need to know about it before their boats sink!

They aren't heat exchangers...What you're seeing is the HVAC (central heat & air conditioning) system pump, which typically are reverse cycle heat pumps. Boat owners who use their boats year round leave heat running during the winter to protect against freezing by keeping the boat warm...in the summer they leave air conditioning running full time to reduce humidity and the molds etc that humidity can cause.

--Peggie

[FabioC]

Originally Posted by peghall

Don't be embarrassed by the question...You're actually smarter than the "average bear." Most people jump the conclusion that bilge pumps are running full time on those boats and that owners need to know about it before their boats sink!

They aren't heat exchangers...What you're seeing is the HVAC (central heat & air conditioning) system pump, which typically are reverse cycle heat pumps. Boat owners who use their boats year round leave heat running during the winter to protect against freezing by keeping the boat warm...in the summer they leave air conditioning running full time to reduce humidity and the molds etc that humidity can cause.

--Peggie

Thank you Peggie, that makes sense and solves the "mystery". I am just a bit surprised that the practice seems so prevalent in winter here in the PNW, since boats left in the water in winter seem to survive well without heating running all the time, but I can see that other owners could think differently.

[OldMan]

FWIW, it is a heat exchanger, it's simply one on the HVAC and not associated with the engine.


A heat exchanger is a device used to transfer heat between two or more media.

[Bill Seal]

Possibly condensate from a dehumidifier.
Or a bait pump