I'm a little fanatical about this
Every time I use the bilge pump on my H36, it pumps out completely, but back fills about an inch of water once it's shut off. I thought these things had a check valve. Is this normal? That inch of water will eventually corrode something.
Thoughts?
Ok, I'll admit it.
I hate water in my bilge.
So, I plumbed all 3 airco unit pans to sump boxes, and ensured that all other small leaks were done with.
But, you still, (on a 49) get nominal hull condensation, etc.
And, yes, you should never put a check valve in your bilge pump.
The standing water in the uphill run can keep the flap from opening, because you get an air lock in the pipe below it.
I used to vaccum my bilge dry with an oil exchanger pump. Got it down to less than 1/4", and I was happy.
Then, I decided to go crazy, and installed an additional bilge pump, (Jabsco), with a pipe that goes straight down to the bottom.
I wired it so that if the normal bilge pump actuates, a relay also energizes this pump. So I now have 2 electric bilge pumps. Plus, I wired it to its own switch, so that I can run it independently.
"Why" you ask?
Well, because when it runs with the main pump, when it shuts off, the backflow in the main bilge pump line leaves 1/2" of water in my bilge.
And as I said, I'm a fanatic, and that's 1/2" too much.
So, the extra pump literereally vaccums the bilge dry.