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A couple of months ago I replaced the original gate valve manifold under the galley sink with brass ball valves. I always hated those gate valves – not being able to visually determine which tank was active – and when it seemed there were problems with the valves I replaced the whole thing. I considered using PVC pipe and valves as others have done, but since I had a bunch of brass & bronze components in my parts kit I decided to go that way.
Everything seemed to be working fine for the first couple of weeks, but then I started to get air into the system. I found a deformed hose nipple on the suction side of the pump and replaced it. That looked good for a few more days then the pump would start sucking air into the lines again. I re-tightened all of the fittings, but I'm still getting air into the lines. I replaced the pump with my backup, which has new, never installed, but it has the same problem. Today I think I've determined that the system works fine (just a little air in the lines) until the tanks get to about 2/3 empty, then the pump will not longer prime the system. My thinking now is that the valves in the manifold are not air tight. They are just household valves, which were probably intended to be on the pressurized side of the pump. It appears that when the level in the tank is well above that of the pump there is enough hydrostatic pressure to allow the pump to prime, but when the water level gets down to the same level as the pump it will not prime.Before I rip this manifold out and replace the valves with something else I thought I'd see if anyone has a different idea on the source of the problem.
Also anyone who has replaced this manifold with ball valves (PVC, brass or bronze) is your system working fine, and what type of valves did you use.One other potential source of an air leak is the filter element I added to the manifold. Before I replace the valves I will remove this strainer, but it is a standard Jabsco stainer designed for this application.
The pump is one of those variable speed Jabsco pumps that aren't supposed to need an accumulator tank (I still have one in the system). I'm not particularly sold on these pumps – they're expensive and I had one fail on me last year. The housing on the original pump developed a crack on the way down the ICW in 2004. The WM in Moorehead City didn't have the same model, so I bought this one. If all else fails I'll probably purchase a much simpler pump and try that.
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Regards,
John Stevenson
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John
My first guess would be that you may not have connected the various parts properly when you assembled the manifold. If you used teflon tape, it’s easy to wrap the tape the wrong way. Pipe-joint compound is easier to use. The easiest way to find a leak would be to pressurize the manifold.Try this. Disconnect the feed hoses from the three tanks. You’ll probably have to put some kind of plug in the ends to keep water from draining from the tanks. A cork should do. Take a short section of hose and connect two of the hose barbs together. For the third, run the hose up to the deck and into a bucket of water. Siphon some water down the hose and then connect it to the remaining barb. you’ll now have a little pressure in your water system. You should be able to observe a water leak wherever the problem exists.
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Rich Carter
Original message
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Thanks, Rich.
You're probably right. It is always difficult to assemble threaded pipe in this manner and get all the valves to line up properly. I may not have seated one of the connections properly. My first step will be to carefully re-assemble the manifold before starting to replace any componenets.On Fri, Mar 28, 2008 at 12:20 PM, < ([email][/email])> wrote:
Quote:John
My first guess would be that you may not have connected the various parts properly when you assembled the manifold. If you used teflon tape, it's easy to wrap the tape the wrong way. Pipe-joint compound is easier to use. The easiest way to find a leak would be to pressurize the manifold.Try this. Disconnect the feed hoses from the three tanks. You'll probably have to put some kind of plug in the ends to keep water from draining from the tanks. A cork should do. Take a short section of hose and connect two of the hose barbs together. For the third, run the hose up to the deck and into a bucket of water. Siphon some water down the hose and then connect it to the remaining barb. you'll now have a little pressure in your water system. You should be able to observe a water leak wherever the problem exists.
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Rich Carter
Original message
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Heck, John, if it takes you more than a couple of hours to troubleshoot, you should just replace the manifold with PVC ball valves and piping. It's simple to do, nearly impossible to screw up, and will last longer than you or the boat (assuming you're over, say 10 years old).
I had them in my Ericson, and they worked just fine for years. I hate the original valves, too, and will replace, but it's really low on the list. I'll use PVC and replace all the hoses since they're tygon tubing. The only reason they don't collapse is because they're stiff from age… 🙂
Bob
On Fri, Mar 28, 2008 at 12:28 PM, John Stevenson < ([email][/email])> wrote:
Quote:Thanks, Rich.
You're probably right. It is always difficult to assemble threaded pipe in this manner and get all the valves to line up properly. I may not have seated one of the connections properly. My first step will be to carefully re-assemble the manifold before starting to replace any componenets.On Fri, Mar 28, 2008 at 12:20 PM, < ([email][/email])> wrote:
Quote:John
My first guess would be that you may not have connected the various parts properly when you assembled the manifold. If you used teflon tape, it's easy to wrap the tape the wrong way. Pipe-joint compound is easier to use. The easiest way to find a leak would be to pressurize the manifold.Try this. Disconnect the feed hoses from the three tanks. You'll probably have to put some kind of plug in the ends to keep water from draining from the tanks. A cork should do. Take a short section of hose and connect two of the hose barbs together. For the third, run the hose up to the deck and into a bucket of water. Siphon some water down the hose and then connect it to the remaining barb. you'll now have a little pressure in your water system. You should be able to observe a water leak wherever the problem exists.
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Rich Carter
Original message
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