Faulty pump or leaky hoses?

[mestrezat]

I'm having a problem with my fresh water pump system. I have four stainless steel tanks that have a capacity of approximately 265 gallons. They're interconnected through a set of four valves(all open). I'm running a Jabsco Par Max 4 pump that sets the pressure at about 40psi in my accumulator tank and water heater. When the tanks are full, the pump runs and pressurizes the system. When the tanks are about half full, the pump just runs and runs and doesn't pressurize the system. I filled the tanks last September and used about half to two thirds of the volume over the last two stays at my boat. That is when I noticed the problem. Since I bought the boat last August, I called the previous owner and he said he had experienced the same thing but when he filled the tanks it stopped. I just filled all the tanks and the pump works fine. Stops right on cue.
Any thoughts as to what the problem might be?

[Charlie]

Accumulator tank does not have enough pressure in it is a possible problem. Sometimes they have bladders in them and a valve that you can add air to the accumulator tank. Had that problem with my well at home and it is the same type of system by the sounds of it.

[Alan Wheeler]

Not accumulator. That is only to act as a smoothing affect on the water flow and reduce the start/stop cycle of the pressure switch. If I understand you correctly, you are turing on the tap and the pump does not keep up with the flow, once the main tanks are below a certain level, correct?? If yes, the issue/s are as follows.
You have a small hole in the pump diaphragm and once the tank gets low enough that the pump has to start lifting, the pump leaks air.
Check you may have a prefilter between tank and pump. It may need cleaning.
If you don't have a pre filter, check you do not have foreign matter stuck in a pump valve.
Ensure you have an inlet pipe size large enough for the flow. One of the greatest restrictions to flow is on the inlet size. It is always prudent to install a slightly larger intake line than the outlet line.

[MidLandOne]

As Alan says, filter fouled or damage to the pump diaphragm - but also suggest check the valves in the pump are not prevented from seating properly by debris (hair or similar is famous).

[mestrezat]

The pump sits below all of the tanks and draws water from my four fresh water tanks. There does not appear to be any type of filter between the tanks and the pump. The line that goes into the pump is a half inch line as is the line out to the appropriate tanks--accumulator & heater.
When the tanks are full, the pump works fine. When the tanks are about half full, it runs all the time and "appears" to add air to the lines. When the faucets are turned on, some air comes wooshing out of the faucets from time to time. The water does not appear to stay in the heater as very little hot water comes from the faucets unless I turn on the pump for quite some time before I need the hot water. Cold works fine after I turn on the pump(again, with the tanks half full)but it also flushes out some air from time to time. With the tanks half full the pump just runs and runs and runs. With the tanks full, it functions just fine.

[Whimsical]

Is the pick up from the top of the tank? May have a pin hole in the pick up tube that lets air in once the level drops below it.

Mike

[Alan Wheeler]

If you have a pin hole in the line, you will have a leak. Most likely a pin hole in the pump diaphragm or valve not seating.

[MidLandOne]

Originally Posted by Whimsical

Is the pick up from the top of the tank? May have a pin hole in the pick up tube that lets air in once the level drops below it.

Or the pickup doesn't go to the bottom of the tanks, although that would seem unlikely one would hope . From the last post it certainly sounds like a complete loss of suction at half tank level, especially as the pump is below the tanks - has all the same symptoms, just like when a tank runs dry.

[Allan S]

I agree with MidLandOne, it could be the suction line was cut too short, OR, if it came off a coil it re-coiled itself after being inserted in the tanks, OR, it has a foot valve (That is a sort of check valve the prevent air getting sucked into you fresh water sysyem) fell off and the ceramic weight above it is lying at the bottom of your tank.

I'd lay even money that your suction tubes have coiled up. You may have to replace the suction tubing inserted in the tanks with a straight, inflexible piece. It is a cheap, easy fix.

Allan

[deltasig]

I do not know if I'm doing the right thing reviving this thread but I run into the EXACT symptoms this season and I wonder if the OP has resolved the issue.
Thank you

[mestrezat]

I ripped out the pump and put in a simple squeeze bulb in the line. Added extra clamps all along the line where it might leak. Put sealant where the steel fuel line attaches to the rubber line. Made sure the Racor filter lid was as tight as I could. Found I had at least some pressure on my gauge on the trip from Palau to Davao, Philippines but there was still some air in the top of the Racor when I got here. I've checked all my lines and find no obvious leaks. The tubes into the tanks are straight(it's a 30 year old boat after all). Still not sure where what air is getting in is getting in. So the problem continues even though the electric pump is gone. Meanwhile, I stop the engine and take off the lid of the Racor and refill it by squeezing the bulb and start all over again.
ah, the joys of boating.

[Lancerbye]

Originally Posted by mestrezat

I ripped out the pump and put in a simple squeeze bulb in the line. Added extra clamps all along the line where it might leak. Put sealant where the steel fuel line attaches to the rubber line. Made sure the Racor filter lid was as tight as I could. Found I had at least some pressure on my gauge on the trip from Palau to Davao, Philippines but there was still some air in the top of the Racor when I got here. I've checked all my lines and find no obvious leaks. The tubes into the tanks are straight(it's a 30 year old boat after all). Still not sure where what air is getting in is getting in. So the problem continues even though the electric pump is gone. Meanwhile, I stop the engine and take off the lid of the Racor and refill it by squeezing the bulb and start all over again.
ah, the joys of boating.

Maybe I missed something on this rethread but, how did it go from a water system problem to fuel system problem? Just wondering.

[deltasig]

Right! I was referring to the water system problem. Thank God, I don't have the fuel system problem

[mestrezat]

Sorry, I'm the original poster and got confused as I had a problem with my fuel lines. Here is what the story is on the water tank and hoses. We filled the tanks again and shortly afterwards it started sucking air again. I tracked the lines from the tanks to the manifold where they all join into one line to the pump. BUT--there are two lines out of the manifold. The second one went to the foot pump in the galley. Since all the lines in were fine and the tubes went to the bottom of each tank, I started looking at the line to the foot pump. The original manufacturer had put in a check valve in the line. One of those that has a swinging flap of metal in it. Unfortunately, they had installed it so the flap swung to the side(if it had swung in years). Over the years, it had locked itself open. When the water level got to below the level of manifold, it went with the path of least resistance. It started sucking air back in through the foot pump in the galley. I took off the gate valve and installed a replacement. a couple of months later, being dissatisfied with the actions of the new check valve, plus that we rarely ever used the foot pump, I installed an on/off valve in it's place. Now if I want to use the foot pump, I have to manually turn on the switch to allow water to flow to the pump. It hasn't been opened in 4 years. Nice to know it's there if we loose power to the pumps but it's still rarely used. Some times you have to go a bit farther to find out the problem.
Sorry about the confusion. But--if you have any suggestions on my fuel lines getting air in them, I'd love to hear about them. Boy, isn't owning a boat fun?

[deltasig]

Thank you for the info. I have a foot pump in the circuit, also, and after isolating it the problem did not get fixed. I started rechecking the water circuit and the problem turn out to be the fact that I left the valves for the hot water tank in the "winter" position since I was not planing to use the hot water. The "winter" position of the valves shuts the one go into the tank and open the other one to drain the tank. The open one created the "leakage" once the water level in the main tank reached the height of the hot water tank valve.
Another mystery solved!