Return line on bilge pump check valve

[Wiredup62]

I have these black lines that run from the check valve back to the sump/bilge all over the boat. They don't make sense to me as quite a bit of water goes through them back to the sump only to be shot out by the bilge pump a second time. Does anyone know why they are engineered that way?

return line.jpg return line 2.jpg

[Pascal]

The only explanation I can think of is a way to prevent air locks.

[MadHatter53]

Maybe as a bypass if the valve gets stuck?

[Wiredup62]

The only explanation I can think of is a way to prevent air locks.

That was my thought, but seems counterproductive.

[wpc691]

That was my thought, but seems counterproductive.

I think I remember reading that the typical bilge pump won’t start against much head. Air lock doesn’t seem likely in that size hose, but if it occurred, the pump might not get started against what would be the large combined head from both sides of the check valve...maybe.

[Pascal]

Or it allows the hose section between the pump and the check valve to drain back which will help the pump start on the next run... I hate check valves on bilge pump. It should be a last resort

[Wiredup62]

Or it allows the hose section between the pump and the check valve to drain back which will help the pump start on the next run... I hate check valves on bilge pump. It should be a last resort

Interesting, that makes sense.

[rwetherington]

it is so the bilge pump does not get air locked.

[Wiredup62]

it is so the bilge pump does not get air locked.

Thank you for the reply. It seems like there would be a better way, as 15% of the water comes right back into the bilge, almost making the pump run longer it seems.