421: Non-return valves on Rule bilge pumps

[BigNut]

Good day, fellow Exotic-Location-Lagoon-Workers.

Having taken up both sailing and boat ownership in November 2018, we have managed to get ourselves out of the hurricane belt for the season, and MANY tasks which we could not get to earlier are being tackled.

All this to say, we are still very new at this, so bear our ignorance in mind.

The problem today, is that while cleaning the port bilge, after removing the 2 water tanks (we have an owner's version) to trace a small fresh-water leak, I noticed for the first time that the outlet to the Rule 2000 bilge pump has a non-return valve.

Rule (Xylem) specifically mentions NOT to do this, see: Rule Pumps Manual, see p 16.

So please help me answer these questions:

1. Why would Lagoon install this in clear violation of the recommended way, or is this an owner issuer? (We have a 1 previous owner 2010 model)
2. Do these need maintenance, and if so, what? And how? It has 4 bolts that screw it together, but is not particularly easy to get to, so will need removal of the 4 hose clamps, and some gymnastics.



Thanks for any enlightenment!
Steve

[AB808]

If your boat is similar to my 420 the overboard discharge is below the waterline. The overboard hose goes up the inside of the inboard cabinet to provide the air lock. Even with this configuration I think the check valve is a good idea. When the boat bounces in the sea the water could be pushed up and over and the valve prevents this flow into the bilge as the check valve creates an air water lock.
I’ve not found a source for the duck valve in these and just replace the entire check valve $25 every couple of years. Eventually they don’t seal closed and leak by.

[BigNut]

Thanks AB808.

Hmmmm. Lagoon must have changed that on our 421 - it discharges from the aft deck, using the manual bilge pump outlet, so well above waterline. I suppose in heavier seas it could still flood the outlet. Still against Rule advice/instructions though.

Steve

[Privilege]

I'm with AB on this one. The one-way valve is often fitted (as I have done) not to help the pump but to prevent water from coming IN. Mine are fitted just inside the hull so that water slapping hard against the side cannot make its way into the bilge.

[BigNut]

Hi Privilege

My question was why does Lagoon install them if Xylem recommends AGAINST using a one-way valve?

I think mine are leaking, as there is a slow return of a small amount of water after clearing the bilge. As my outlets are well above the waterline, I wonder how much benefit they provide, or if they were perhaps a hold-over from the 420?

(Mine is a 421)

If fitted to stop seawater ingress, it makes sense to add them close to the exit. But mine are within a few feet of the pump.

Steve

[AB808]

Any restriction in the hose reduces the pump gpm flow. Considering the normal lift in the plumbing, it doesn’t take much debris in the pump or restriction in the hose and they don’t pump the water out. The manufacturer is stating such in there install literature. It’s a trade off, I for one have two pumps in each bilge the both the auto and manual. Both have non return valves. When it’s gets rough, and really big seas and the boat is pounding the last thing I want is water finding its way into the boat though the overboard bilge plumbing.
I’ll trade this for the reduced flow rate and just add on the manual pump if the auto isn’t moving enough water. These are wired so when I override the float switch on the first one the second pump (whale, no float switch) is energized.

[dfelsent]

I’ve been in the middle of the Cabot Strait At 3 am in very rough seas aboard a sinking boat due to no anti siphon loop on the electric bilge pump. Very scary.

I’ve also had batteries go flat because of the water in a hose going past a leaky non-return valve refilling the bilge every minute or two when in cam conditions on a mooring.

Vented anti siphon loop is what I do now. Helps fix both problems.

[ggray]

Rule says to use a vented loop, not a check valve.

The reason is that prior to the water leaking back through the check valve, which it ultimately will, that weight of water will be enough restriction that an air lock can result in the pump NOT pumping.

My boat came with the check valves installed from the factory. Reason, I believe, is that there is insufficient height (because of cabinetry) for a vented loop fitting to be properly installed, or to be completely effective. I have once or twice (after 18 years) observed an airlock, so it can be a problem.

I removed the check valve on one side because of this, but plan on relocating it much higher in the line, maybe after the hose curves downward to the thruhull. I think that's the secret to success, and should address the reason Rule doesn't like check valves.

Interestingly, the oversized pumps I installed for emergency (at same time replaced the Rules with the smallest Rule available for initial pumping) came with an optional check valve flap that could be installed directly on the pump. I think they were Johnson pumps. They are orange, anyway, for identification.

[James S]

Originally Posted by BigNut

Hi Privilege

My question was why does Lagoon install them if Xylem recommends AGAINST using a one-way valve?

I think mine are leaking, as there is a slow return of a small amount of water after clearing the bilge. As my outlets are well above the waterline, I wonder how much benefit they provide, or if they were perhaps a hold-over from the 420?

(Mine is a 421)

If fitted to stop seawater ingress, it makes sense to add them close to the exit. But mine are within a few feet of the pump.

Steve

I'm pretty sure that even if the check valve is working properly the water in the line between the check valve and the pump would drain back into your bilge...

[Sailmonkey]

Originally Posted by BigNut

Hi Privilege

My question was why does Lagoon install them if Xylem recommends AGAINST using a one-way valve?

Steve

Why? Because Lagoon is not omnipotent!

I’d guess they have an unacceptable amount of water in the line returning to the bilge after the pump turns off (thereby turning the pump back on) and used the check valve to “fix” the problem.

The real solution to this is to only use the centrifugal pumps as de-watering pumps and use a remote mounted diaphragm pump as the primary maintenance pump.

[Privilege]

I think that sailmonkey has it right. The hose is big and long enough that once the bilge pump stops, it contains sufficient water to run back down into the bilge and set the pump running again...a never ending cycle that will run down your batteries very quickly. One-way valves never completely stop the water, they only slow the process down.
Another possible solution is to have a second much smaller bilge pump with a small hose mounted just below your main. This will keep the bilge dry and your main pump remains on standby for emergencies. I've done this and ran the hose from the small pump three feet to my shower sump.

[BigNut]

Thanks for all the replies. I’m going to think this through a bit more, and then make some changes.