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Old 03-26-2019, 11:40 AM   #1
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Check Valves

Iím replacing some of the plumbing on my trawler and looking for advice on using check valves on the bilge pumps. As it is now, my pump will almost dry the bilge.... until it shuts off. Then the water in the hose will flow back into the bilge. Thanks
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Old 03-26-2019, 11:45 AM   #2
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I use a one-way check valve on my primary bilge pump just like you describe, to prevent water from retreating back into the bilge after pumping. I believe Rule makes them and most marine stores have them.
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Old 03-26-2019, 11:56 AM   #3
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Depending on wave conditions I use to lose the prime on my AC pump a lot when turning on after traveling....Added one to my AC system between the through hull and strainer....never lose prime any more.
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Old 03-26-2019, 12:07 PM   #4
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Conventional wisdom is that a check valve can malfunction and block the bilge pump from pumping out. Especially with the debris that is typical of some bilges.

However, a lot of people have a set up with a smaller pump as the primary to keep modest amounts of water out of the bilge, and a larger dewatering pump slightly higher in the bilge in case the primary is overwhelmed or fails. If that's the case, then I would argue you could put the check valve in the smaller, primary pump and in the unlikely event it fails and blocks discharge, you can figure it out and replace it when your back up pump starts operating. I would still have an anti-siphon installed in the line with the check valve.

If you only have one bilge pump, I would recommend against it.
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Old 03-26-2019, 12:11 PM   #5
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Conventional wisdom is that a check valve can malfunction and block the bilge pump from pumping out. Especially with the debris that is typical of some bilges.

However, a lot of people have a set up with a smaller pump as the primary to keep modest amounts of water out of the bilge, and a larger dewatering pump slightly higher in the bilge in case the primary is overwhelmed or fails. If that's the case, then I would argue you could put the check valve in the smaller, primary pump and in the unlikely event it fails and blocks discharge, you can figure it out and replace it when your back up pump starts operating. I would still have an anti-siphon installed in the line with the check valve.

If you only have one bilge pump, I would recommend against it.

That seems like a good approach.
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Old 03-26-2019, 01:52 PM   #6
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I would not put a check valve on the primary bilge pump but would put a stripper pump to get the last bit of water out and would not have a problem with a check valve on it. Then if the check valve gets stuck you still have your primary pump functional. Check Whale pumps they make some with check valves just for this purpose.
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Old 03-26-2019, 08:22 PM   #7
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As mentioned, I have one on my small primaries and not on the large secondaries. Have never had an issue, but then my bilges are usually dry.

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Old 03-26-2019, 10:02 PM   #8
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The newer Rule bilge pumps have a check valve built into the outlet of the pump. They have also changed the design so they no longer get a air lock and not pump. I use one of these new pumps in my shower sump. Works great.
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Old 03-26-2019, 11:05 PM   #9
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Rule 27SA 1100gph comes with a 1" and 1-1/8" hose size ends. Each has a rubber check valve.
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Old 03-26-2019, 11:06 PM   #10
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A small diaphram pump will remove almost all the water and not allow the backflow.

I set up what is now a very old Jabsco diaphram type bilge pump to do just that and it works very well at doing that. Is it going to be much help in a flooding-no - but for that gallon to two that collects over a few days it does the job well. It is mounted out of the bilge with a hose and then a small strainer one the hose end. It is slow but that's all that is needed. I did not set it up as automatic although could be.

Consider one of those from the used market OR look at the Whales, Attwoods.

Just make the effort to get the Jabsco bilge pump valves. They are different from the pressure water valves.
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Old 03-27-2019, 01:52 AM   #11
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One of my marina neighbours, still ashen faced,had a nasty experience with a non return valve which spectacularly failed on his Riviera 48. Fortunately the lazarette bilge pump outlet,at sea level,was fitted with a seacock which was ultimately deployed. When discovered,the otherwise well sealed lazarette contained a very large quantity of seawater entering via the outlet.
The installation is thought to be a non Riv aftermarket job, the outlet line is being replaced with a vented loop for now. Take out is: beware of non return check valves which if failed can cause sinking or otherwise serious problems.
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Old 03-27-2019, 07:30 AM   #12
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Rule 27SA 1100gph comes with a 1" and 1-1/8" hose size ends. Each has a rubber check valve.

These new Rule check valves work great at stopping the water rush back into the bilge when the pump switches off.

Instead, the water slowly trickles back in to the bilge.
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Old 03-27-2019, 08:27 AM   #13
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Avoid them if you can...especially up north

Quote:
Originally Posted by offbeat View Post
Iím replacing some of the plumbing on my trawler and looking for advice on using check valves on the bilge pumps. As it is now, my pump will almost dry the bilge.... until it shuts off. Then the water in the hose will flow back into the bilge. Thanks

Avoid them if you can, especially in cold climates. One more thing you need to winterize, but you will probably forget. Then they freeze, crack, leak etc.


In some cases, the drained area is so small and the hose is so long that the backflow from the hose will be enough to cycle your float switch. In this case you can maybe raise your float switch a little before resorting to a check valve.


Since your bilge pump cannot completely empty your bilge anyway, the extra 12 ounces of water or so that you are carrying around is not going to be an issue.
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