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Old 31-01-2015, 07:43   #1
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Air Leak in Fresh Water Pressure System

despite flushing all air out of my pressure system the pressure pump turns on after a while again and air has leaked into the system somewhere.
I cannot find any water leak from the hoses or pump. I put in double hose clamps and tightened them. I installed double check valves before and after the pressure pump. But these plastic valves may not be to tight and allow backflow into the water tank. But then how does air get back into the system?
Presently, I have to turn off the pressure pump after use and at night.
Oddly, sometimes I forget and it stays off all night. At other times, after 5 minutes the pump turns on and keeps pumping air until shut off.

Q: Is there any way to find where air enters the pressure system?
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Old 31-01-2015, 09:18   #2
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Re: air leak in fresh water pressure system

Ours did similar had a micro crack in the bellows on top and it all depended on what position the pump stopped in how long it took to take on air also could be the pressure switch seal leaking
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Old 31-01-2015, 09:55   #3
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Re: air leak in fresh water pressure system

All pressure pumps come with Troubleshooting guides in the manuals, which are available online. Also good to see what the pump is made of inside. They're all pretty much the same construction if it's a standard diaphragm pump.

I had a small leak in one of my hoses that ran below the engine bed to our aft head sink. Impossible to find, but that was the culprit. I replaced the hoses. Issue solved, although I originally thought it was the pump.

I did do the pump test diagnostics first, including taking off the inlet and then the outlet.

We can't help you do the actual work on your system from here on the internet, but we can tell you how to troubleshoot.

Good luck.
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Old 31-01-2015, 13:18   #4
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Re: air leak in fresh water pressure system

Thanks Stu. Testing the pump? Can I vent it, then run it, then disconnect the intake and no water should flow back out of the pump? In that case it can't be the pump. It would have to be a leak in the connection after the pump? Then trace the hoses from the pump.... Is there an additive to water that shows up bright under UV light? I could feed water into the pump from a bucket with that stuff. Just food coloring would not be well visible under gear and floors and cabinets.
Thanks for your help
wolfgang
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Old 31-01-2015, 13:36   #5
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Re: air leak in fresh water pressure system

First thing I did was disconnect the outlet, slap a three or four foot hose to it and bend the hose, then turn the pump on. That'll tell you if the issue is on the pump outlet inside the pump. If it doesn't cycle, the hoses on the boat are suspect. If it still cycles, it's either the hoses or the pumps. Go from there. For further info, check the guides I suggested.
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Old 31-01-2015, 13:53   #6
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Re: air leak in fresh water pressure system

Disconnect the output hose from the pump, then connect a section of hose to the pump that has a cock on it, turn the pump on, bled the air and close the cock.

Now if the pump comes up to pressure, and stay off, you know the issue is on the pressure side, not the suction side, or the pump it's self.

Lloyd

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Originally Posted by WolfgangSeaLife View Post
Thanks Stu. Testing the pump? Can I vent it, then run it, then disconnect the intake and no water should flow back out of the pump? In that case it can't be the pump. It would have to be a leak in the connection after the pump? Then trace the hoses from the pump.... Is there an additive to water that shows up bright under UV light? I could feed water into the pump from a bucket with that stuff. Just food coloring would not be well visible under gear and floors and cabinets.
Thanks for your help
wolfgang
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Old 31-01-2015, 14:15   #7
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Re: air leak in fresh water pressure system

If you are not able to find the leak then try adding a timer switch. Locate it near the galley sink. Turn it on when you need water and the switch turns itself off.
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Old 31-01-2015, 14:22   #8
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Re: air leak in fresh water pressure system

I had a similar problem. Turned out to be a cracked seal in the accumulator bleed valve. The unit was in a wardrobe near the pump!!. Couldn't figure out why my shirts felt damp.
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Old 31-01-2015, 17:21   #9
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Re: air leak in fresh water pressure system

We had a total of 5 Whale Freshwater Pumps fail over a period of 2 years (four for leaks and one because the pressure switch was not properly adjusted making the pump cycle on and off as it approached cut-off pressure). Our system (a catamaran) allows us to isolate each pump from the system (only one pump/water tank is used at any time) so we were always able to isolate the pump as the leaking component. I finally got tired of warranty replacements that would fail again and changed to Shurflo Freshwater Pumps. They prime faster, run quieter with better pressure and we have had no leaks since making the change. I did keep the one Whale pump that did not have a leaking diaphram and replaced the pressure switch from the other pump and kept it as a spare.
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Old 02-02-2015, 10:32   #10
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Re: air leak in fresh water pressure system

Quote:
Originally Posted by WolfgangSeaLife View Post
Q: Is there any way to find where air enters the pressure system?
One thing you can do is, with the pump running, drip water around the vacuum side connections to see if the water drops are sucked in.

If that doesn't help you can try pressurising the vacuum side line and look for water leaks. To do this you will need to close the valve to the tank(s), insert a "T" somewhere between the tank(s) and the pump and connect the "T" to a dockside faucet with a garden hose. You may want to limit the pressure by using a pressure reducer which you can get in an RV or good marine supplier.

Good luck!
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Old 02-02-2015, 18:22   #11
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Re: air leak in fresh water pressure system

Quote:
Originally Posted by WolfgangSeaLife View Post
despite flushing all air out of my pressure system the pressure pump turns on after a while again and air has leaked into the system somewhere.
I cannot find any water leak from the hoses or pump. I put in double hose clamps and tightened them. I installed double check valves before and after the pressure pump. But these plastic valves may not be to tight and allow backflow into the water tank. But then how does air get back into the system?
Presently, I have to turn off the pressure pump after use and at night.
Oddly, sometimes I forget and it stays off all night. At other times, after 5 minutes the pump turns on and keeps pumping air until shut off.

Q: Is there any way to find where air enters the pressure system?
How do you know it's pumping air and how do you know air is getting into the system?
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Old 02-02-2015, 18:46   #12
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Re: air leak in fresh water pressure system

If air is getting into the system the leak must be on the suction side of the pump. Any leak on the discharge, or pressure side, would let water OUT, not let air IN.


Air leaks on the suction side can be a bugger to find - nothing leaks out. You basically have to check every connection for tightness. Pink thread tape is much better than the white stuff BTW.


I had a similar issue, and it turned out to be the cheap PVC valves I had on the water tank header. The air was getting in down the handle shafts.
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Old 02-02-2015, 21:50   #13
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Re: air leak in fresh water pressure system

If you have a pinhole in the accumulator diaphragm, the unit will pressure up and switch off. The water will then slowly move from one side of the accumulator diaphragm to the other thereby releasing the pressure on the diaphragm and so turning on the pump switch. No air will escape and no water will leak. One indication of this MIGHT be that the pump switches off very quickly after you turn off the tap.
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Old 02-02-2015, 22:32   #14
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Re: Air Leak in Fresh Water Pressure System

The most common cause of a pump cycling as you describe are leaky valves in the pump. The pump builds up pressure on the discharge side, shuts off, the water leaks back to the tank through the defective valves, and the pump turns on again. Rebuild or replace the pump and I bet your problem goes away. You probably don't have an air leak.
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Old 03-02-2015, 07:18   #15
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Re: Air Leak in Fresh Water Pressure System

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The most common cause of a pump cycling as you describe are leaky valves in the pump. The pump builds up pressure on the discharge side, shuts off, the water leaks back to the tank through the defective valves, and the pump turns on again. Rebuild or replace the pump and I bet your problem goes away. You probably don't have an air leak.
I actually typed most of that and then read that the OP had already installed check valves on both sides of the pump. That's when I changed my post to ask how he knew he had an air leak.

You are absolutely correct and I have had two pumps fail the way you explained.

As inexpensive as these pumps are, replacing the pump is probably the best thing to do, assuming he's already done a thorough check for water leaks (including a transom shower if he has one). The original can be kept as a spare for emergencies.
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