A/C Loss of prime

[Bob Rutland]

On our 84 H31 we have a factory installed King Air air conditioner unit. When we return to the dock after a sail the unit has lost it's prime. I have to remove the seawater cooling line(on the a/c unit side of the pump)and blow thru it in order the regain the prime.Has anyone else had this problem ? Would a check valve solve the problem? Thanks, Bob S/V Lady Di II

 

[Ed Schenck]

No, but a question.

Have not had the problem but have a Mermaid with a bleed valve in case it does. This bleed valve is in the hose between the pump and the unit so that air in the line can be bled off. Is your pump lower than the unit input? And do you close the thru-hull when sailing? If yes to both questions then I'm not sure how you are losing prime. Can you call the manufacturer?

 

[Bob Rutland]

Thanks Ed, but......

I don't think closing the thru-hull will help because the A/C intake is almost in the very bottom of the hull just aft the keel.The pump is just a little lower than the unit. Thanks for the idea, Bob

 

[Clyde Lichtenwalner]

Close Valve

Close the seacock when underway and your problem will be solved. Loosing prime is not uncommon when the seacock is as shallow as the canoe body of an H-31. Betweem heeling, wave motion, and bubbles under the hull, some air is probably taken into the thru hull and trapped in the centrifugal pump. Hose runs are complex and air probably just can't work its way out of the pump without some help. A check valve may help, but the simplest and safest solution is to manually close the seacock when underway.