Shower drain trouble

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scott dube

My shower drains into an add on west marine shower sump kit. It shares a discharge hose with the bilge pump via a tee. There are check valves on either side of the tee to prevent either pump from discharging thru the other pump. It seems like there is a hydraulic lock because the shower sump cannot pump out. I thought it might be the bilge pump pressurized the line too much so I loosened the clamps on that side and let it drain. Still didn't fix it. Now I have let the shower sump pump into the forward bilge and then the bilge pump picks it up and sends it overboard. I don't like this solution long term because of bilge smell and so on. My theory is that eithe the pump is worn out or the height of the thru hull discharge is too much for that pump. Any ideas? Scott
 
Sep 24, 1999
1,511
Hunter H46LE Sausalito
try this

Before you attempt anything drastic, you might try backflushing the shower drain from the sump side. just use a regular garden hose. i find that i have to do this a couple three times per year because of soap build-up. (my sump, on a 410, has to stand up to daily showers, the boat being a liveaboard.) also, pull the sump pump off it's bracket and make sure their isn't any hair below/around the rotor, which will keep it from re-priming. good luck.
 
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Arthur Boas

Lift a problem

I believe the water lift is your problem. These sumps are not rated at anywher the same lift capacity as a bilge pump. Maybe try another above water line through hull nearer to the sump if you have one.
 
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Chris Van Lauwe

Separrate discharge line

I I thought that the marine code specified that you had to have a separate discharge line and not a tee? Perhaps I was mis-informed. Chris Festina Tarde 340
 
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Peggie Hall/Head Mistress

There is no "marine code"...

...that's comparable to building codes. There are ABYC, UL, NFPA standards, but following them is voluntary, not required. However, I know of none that require separate drains for different applications...in fact, many boat builders who religiously follow standards who try to combine as many as possible to reduce the number of thru-hulls.
 
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Scott Dube

any ideas Peggy?

You of course are the recognized expert around here on this type of topic. I had already flushed the line as suggested as well as made sure of no obstructions in the pump pick up. What do you think of the lift considerations of this pump? Thanks, Scott
 
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Peggie Hall/Head Mistress

I've been reading the posts, scratching my head...

The lift shouldn't be a consideration...a good pump that's working to specs should be able to lift water 6' or more. Something else is screwing things up, but without seeing it, I haven't figured out what yet.
 
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Peggie Hall/Head Mistress

Just read it again...

You don't suppose one or both of the check valves could be installed backwards????
 
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Scott Dube

check valves...

No the check valves are facing the correct way. As I said this was an add on from the previous owner so it came from West Marine. Consequently the valves are jabsco flappers which have nice little arrows. I also made sure that the label was put on correctly. Thanks, Scott
 
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Arthur Boas

Lift... again

I'm sure this is a lift & pressure problem. The issue is that the bilge pump hose is a fairly large diameter (or at least should be), versus the 3/4 inch hose you run from the shower sump. The sump is now trying to lift the weight of the existing water and breaking the check valve seal which is being kept shut by the weiight of the water behind it. This won't work unless you have a stronger pump. In fact, I've seen bilge pumps with check valves which won't function because of the back pressure on the check flap. You can prove this by disconecting the bilge pump line and allowing the standing water in the hose to drain to the bilge. Now reconnect and try the sump. It may possibly work, but will not work again once you shut it off because of the back pressure on the check valve.
 
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Scott Dube

I think Arthur is right!

Arthur, I think you are correct it is fact the diameter of the discharge hose and the assoicated weight of the water contained in it that creates the problem. The trouble I had was that to try and prove this theory (last week) was that I merely loosened the clamp on the bilge pump side. I don't think this provided sufficient relief in the discharege line. It needs to be practically empty in order to work right. I am leaning towards adding another thru hull discharge when we pull the boat this fall. Thanks, Scott
 
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