Bilge pump check valve

[knotflying]

I have one of those flapper type check valves on my #1 bilge pump, but I noticed a fellow tugger does not have one. After reading a few articles about check valves and bilge pumps, it seems a check valve is not recommended. Anyone else have opinions or experience with removing theirs and the results?

 

[Osprey]

Without an anti-backflow valve (check valve) on the aft bilge pump a cyclic on/off situation may occur. That is, the pump runs until turned off by the low water sensor, but there is still water in the hose leading to the through hull fitting. With the pump off this water flows back into the bilge and the water sensor turns the pump on again. The process becomes repetitive. The down side of a check valve, is that on some "system" designs, the water held in the hose, between the valve and through hull, can prevent the pump from pumping more water into the hose - too much back pressure for the pump to pickup a pumping action. On my previous boat I had to remove the check valve so that the pump could be effective. This also meant that I could not use a water sensor in the pump circuit - manual operation only. I have had no such problems on my R27.

 

[Brian B]

Knotflying and myself are at the same marina in FL and we noticed that my bilge pump pumps with more force than his. For whatever reason my boat does not have the check valve. A couple of articles that I read do not recommend the check valve for pressure reasons and restrictive flow. What is recommended is a high route of the discharge hose above the overboard discharge which is how mine is routed. The back flow of water when the pump turns off is minimal and does not cause the pump to continuously cycle. One article by a marine surveyor who dislikes the check valve wrote that the back flow is actually good to flush debris out of the impeller area.
No need to winterize the line either as there is no water in it.

 

[SGIDAVE]

Osprey points out the common plus/minus of a one-way valve within the bilge pump tubing. A good idea in principle.

But in practical application, they are problematic as they not only reduce flow but can become inoperable when debris plugs them up. Even without debris they can become less-pliable over time and result in considerable resistance yielding a "weak stream."

Regarding the 'short-cylcing' when the bilge hose water flows back into the bilge... is only an issue if the volume of the bilge space is so small that a cup or two of water (or the amount that flows back into the bilge when the pump stops) causes the float switch to activate the pump's auto function. Based on what Brian says above, that is not the case.

Avoid a WEAK STREAM and ditch the anti-backflow valve.... 🙂

/dave

 

[LADYBUG TOO]

I took the check valve out of the aft pump on Ladybug, Too and it short cycled because the space around the aft pump is quite small on my R-29 classic. The flapper can be turned over to keep it functioning properly. Mine has lasted since 2010 when I brought her home. I did replace the electronic bilge switch with a Rule Float Switch that can be easily popped out. Also I relocated the check valve so that I can get to it easily. It helps to have a heat gun to remove the whole valve but don't over do it. I melted the factory hose and had to replace it. But that is not my only FUBAR. Do it yourself maintenance does carry some risks but I have not totaled the boat yet so I must be doing a few things right.

Pat
Ladybug, Too