Dessalator Operational Question

Mark & Debbie Mueller

We have an A54 with a 230v 160 LPH Dessalator, water cooled air conditioning, and a Volvo 110 HP engine. 


1) When operating the Onan, water maker, and the Volvo above approximately 1250 RPM the low-pressure gauge on the water maker drops from 20 psi to negative 10” hg, the high-pressure pump starves, and the water maker shuts down.


2) When operating the Onan & water maker everything operates correctly IF the air-conditioning is started first.  If the water maker is started before the air conditioner when the water maker is started the low-pressure pump pressure drops and the water maker shuts down due to low-output pressure on the high-pressure pump.


All tests were run with a clean sea strainer and a clean raw water intake pipe, it was scrubbed with a round brush that reaches through the hull.


What has been your experience?  Any thoughts?  Thanks in advance.


Mark & Debbie Mueller

A54 – 68

Brass Ring

Ft. Lauderdale


Just a guess, based on the key input that starting the AC first makes it work...

I'm betting the check valve on the AC water system is leaking and air is being sucked backwards through the centrifugal pump.

Bill Kinney
SM160, Harmonie
Great Guana Cay, Abacos, Bahamas