Proper Float switch positioning for bilge pumps

LittleWingCA · #1 (**permalink**) 09-16-2010

Hi Everyone:

After washing down the sailboat this past weekend, after a great day of sailing, I noticed the bilge pump was running but no water was exiting the boat. Further inspection showed that the float switch was being activated by about 1 inch of water in the bilge, but that wasn't enough to cover the input grating of the bilge pump so the pump couldn't get rid of the water. I guess the previous owner mounted the float switch too low. Is there a recommended height above the pump that the float switch should be set up to? I guess you want to ensure the pump is immersed first, but is there any standard? Are float switches the best way to go, or are the 2 prong water sensors better?

Hartley18 · #2 (**permalink**) 09-16-2010

A good question...

There isn't really any "standard" since every boat is different, but it is pretty important to follow the instructions that came with the bilkge pump and float switch. In most cases, having the switch 1" higher than the pump inlet is enough. Perhaps you can refit your switch on a block of wood to make it start later?

As to which type, I prefer the float-type because they're cheaper, more readily available and easier to replace. They also have built-in hysteresis (on and off isn't in the same place, meaning your pump isn't as likely to be stopped and started continually) which the 2-prong types don't usually have..

Hope this helps.

tdw · #3 (**permalink**) 09-16-2010

Oh for a bilge pump that can actually get to that last inch of water.....

Hartley18 · #4 (**permalink**) 09-16-2010

Quote:

Originally Posted by tdw

Oh for a bilge pump that can actually get to that last inch of water.....

Oh, they do exist.. it's called a "wet vac" and you can buy one at Whitworths for less than a float switch.

Every boat should have one!!

LittleWingCA · #5 (**permalink**) 09-16-2010

I agree. I have a wetvac as well, and will use it to remove the 1" of water, but now I need to reposition the float switch as well. Question is, can you adjust the turn on and off settings to try and get most of the water out between the switch and the top of the pump opening.

Hartley18 · #6 (**permalink**) 09-16-2010

Quote:

Originally Posted by LittleWingCA

I agree. I have a wetvac as well, and will use it to remove the 1" of water, but now I need to reposition the float switch as well. Question is, can you adjust the turn on and off settings to try and get most of the water out between the switch and the top of the pump opening.

Not usually. You need to position the switch at the correct height instead.