Check valve for bilge pumps?

[dcstrng]

I’m of the high-loop, no moving parts, KISS school – second to that is the siphon-break. I wrestled with this on our boat for a week or so, and thought long and hard about a one-way valve, but there was no way that I could then keep all those parts/connections where I could easily monitor/maintain them, so in the end I half-disassembled the back of the boat and made way for the high-loop – which had the side benefit (for my worry-meter) of zero connections except at the thru-hull and the pump. I was fortunate and the amount of water that stays in the hose isn’t enough to retrigger the pump (until more liquid accumulates in the bilge), but that was pure luck. I can’t imagine there is a boat on the planet where a high loop can’t eventually be done, but I can attest there are many where it seems a rather daunting project.

[rlaggren]

I'm not necessarily against check valves. But the Bosworth mentioned above appears a very bad product for two reasons: It's hard to open from the closed position and it physically can NOT open more than half way.


The materials seem good, the assembly seems good, but the designer needs to be reassigned to digging ditches just for the safety of the rest of us.

[rwidman]

A check valve in a bilge pump line is a "no - no". It will clog and either fail closed (effectively disabling the bilge pump) or fail open (effectively disabling the check valve).

As some folks have mentioned, if you have a problem, a loop id the best solution.

[rlaggren]

I have read many many threads on check valves and clearly the common wisdom is NOT.


But what I have not seen is first person or technical descriptions of problems on record. I have seen dozens and more sensible practical reasons to avoid check valves, but not actual witness of problems, in service or in testing. In particular problems involving sticking closed. It's very possible I will come upon this info - I am certainly looking for it as it's often easier to learn from others than run ones own tests. But at this point, all I have seen is theory, hypothesis, generalized warning, etc.



I believe in KISS. But I also believe in facts and detailed evaluation of actual events. And I also believe in the occasional reality of excellent products. The devil, the reality, is in details. The blanket dismissal of check valves does not carry as much weight with me as it may with some - there is almost always a place/time/situation for almost everything. Whether a particular choice is wise or even available considering other constraints (time, money, good information, supply...) is an issue that depends entirely on specific situations.


For example: If I were a professional installing bilge pumps, I might well refuse to install check valves if two fact were true: The valve required maintenance every 3 months (or some such) _and_ I felt that I could count on customers NOT doing that maintenance. It would not be responsible to risk liability and damage to my reputation by customers who almost for sure would not follow required maintenance. However. If I had confidence in the functioning of that valve under good maintenance, I might well install it in my own boats. Different situations, one answer does not fit all.


As in the above example, businessmen _must_ tailor their offerings to avoid easily foreseen trouble. This factor controls every business, service, hardware, everything. The recommendations and products from any business are always severely limited by this simple issue. That doesn't mean the the methods and tech _not_ offered are bad - it can mean the biz sees a biz problem with offering them and do doesn't make them available and probably doesn't even mention them.



I posted here because I have seen at least two people on various forums who have reported satisfaction and trust in the Bosworth check valve and I personally have had one in my hands. I do not feel it's a good product for the reasons mentioned, even though it's well put together. I have NOT seen or heard of one failing in any way and I have not tested the reduction in flow when using the valve; I could see _no_ reason to think it likely to fail either short or long term. The action and limitations of the valve looked to me like it would have to cause severe restriction such that it was not suited to my purpose, even though well made.

[phorvati]

I have check valves on all three of my pumps. Rule 3700, rule 1500 and rule 360. They work, but I have not had a real emergency to see how things behave when stressed to the max. I clean valve, hoses every few years.
I have anti siphon on the two big ones as they discharge below water. I can't imagine what 15 feet of 1.5" hose full of water would do, if water returned every time.

[rwidman]

Originally Posted by rlaggren

I have read many many threads on check valves and clearly the common wisdom is NOT.


But what I have not seen is first person or technical descriptions of problems on record. .

That is because most folks are smart enough to follow the advice of not to install a check valve on a bilge pump discharge. Those who have done this anyway are not likely to post about their failure.

I had a home with a deep well for potable water and I had check valve failures a couple of times. This was clean drinking water.

The water in your bilge is not clean drinking water. If contains oil and anything that falls into the bilge. Dirt, pebbles, bits of wire from wiring repairs, wire ties, leaves, you name it, it will be in your bilge.

When your bilge pump pumps, it will pump this junk to the check valve and potentially clog it.

[Caper]

If you select the highly rated Ultra bilge pump switch, note that the PS 02 version does not work well for bilges with longer/sloped discharge hoses. When the water drains back it initiates an endless cycle of pumping. The PS 04 version here has a greater differential for the on off depth set points that overcomes this problem and avoids the need for check valves We mistakenly purchased the #02 version as a replacement for our 15 year old Ultra switch - creating misery. None of the vendors explain the #04 option.

[Shanachie]

There's nothing wrong with a check valve on a small bilge pump used to empty water from small leaks, the stuffing box, etc. On many boats, if you don't have one, you will always have water in the bilge and a skanky odor in the boat.


If the check valve clogs, you normally have a minor headache until you fix or replace it. The best spot to put the check valve is next to the bilge pump, where it is easily accessible for cleaning and repair.



The caveat here is that a small bilge pump -- anything under about 2,000 gallons an hour -- is not going to do much to save your boat in an emergency anyway.



That 800 gph Rule will actually pump maybe 500 gph. A 1.5-inch hole a foot under the waterline will allow in about 2,500 gallons an hour, according to BoatUS.


As some basic math shows, an unattended boat will sink rather quickly at the dock unless you happen to arrive just as it begins. Your only hope is a dock neighbor notices and tells the marina.



For emergencies while I'm on board, I have a 2,000 gph portable pump (maybe more?) with a long two-inch hose that can be quickly clipped to the house bank. The hose leads to the cockpit and out the open stern.


I also have the wooden bungs and items such as small towels that can be jammed into a hole and slow the leakage into the boat. It helps to have through hulls that are easily found and accessible.


A clean bilge also helps. Nothing with paper labels should be stored down there. With a dry bilge, it's also easy to spot screws and the like that could jam the pump.

[GordMay]

Originally Posted by Caper

If you select the highly rated Ultra bilge pump switch, note that the PS 02 version does not work well for bilges with longer/sloped discharge hoses. When the water drains back it initiates an endless cycle of pumping. The PS 04 version here has a greater differential for the on off depth set points that overcomes this problem and avoids the need for check valves We mistakenly purchased the #02 version as a replacement for our 15 year old Ultra switch - creating misery. None of the vendors explain the #04 option.

Indeed.
For the same price [$200 List], the UPS-04 has a 2-1/4" on-off difference, vs the UPS-02, at 1-1/4" delta.
➥ TEF-GEL - Ultra safety systems - Home page

[NevilleCat]

Originally Posted by Caper

If you select the highly rated Ultra bilge pump switch, note that the PS 02 version does not work well for bilges with longer/sloped discharge hoses. When the water drains back it initiates an endless cycle of pumping. The PS 04 version here has a greater differential for the on off depth set points that overcomes this problem and avoids the need for check valves We mistakenly purchased the #02 version as a replacement for our 15 year old Ultra switch - creating misery. None of the vendors explain the #04 option.

Hey, thanks for this!