Rumbling Fresh Water Pressure Pump

[Nightowl]

Recently our pressurized fresh water system pump started making a low rumbling sound when the system was left switched on but no demand was being placed on the system. The rumbling will sometimes stop and leap into normal life if you momentarily turn on a water tap but usually it returns a short time later. The noise is quite different to the normal sound the pump makes under normal load. - It will usually continue until the power switch to the system is turned off. Having said that there are times when it will work normally with no rumbling for hours. It took some time to even work out where the noise was coming from.

The pump is only about 12 months old and the problem has just started. I wondered if there was a slow leak somewhere but cannot seem to find one although it is difficult to access all the plumbing. This wouldn't explain why sometimes the rumbling doesn't occur.

Can anybody suggest what may be causing this. It means we can't leave the system turned on. Instead we are having to turn it on and off everytime we want to use a tap.

Cheers
Nightowl

[Pete7]

Well either the pump is fecked or something else is happening. Air in the system perhaps, or how about the expansion tank not working. If the pump is less than a year old, take it back and get a replacement. Presumably it was working okay when newly fitted.

Pete

[Mark Zarley]

The pump is pumping. Want to verify if you have a fresh water leak, monitor your bilge. You don't mention the make of the pump. We use a Par Max and every 2 or 3 yrs have to put a new pressure switch on the head, darn thing wants to run all the time. Yours sounds like it is not turning off when it reaches the 'cut off pressure". Under normal operation as the pump builds pressure the sound coming from the pump deepens, I suspect the deep sound (rumbling) you hear is the pump continuing to pump beyond it's rated cut-off point. sounds like a new pressure switch or regulator is needed. Want to check? Install a cheap pressure guage on the pressure side of the pump and compare to pumps specs.

[Sunspot Baby]

If you have a fresh water leak, then you should be running out of water much sooner than expected.

Mine growls when it start picking up air, either because the tanks are low or there in a leak in the intake. Don't know if your rumble is the same as my growl.

George

[zeehag]

the rumbling noise is your pump pumping. you are experiencing either a leak or air in your system. if you can goto a dock to fillyour water, do so with the taps running until is filled turn all off. leave the dock and go to where ever it is you keep your boat. if you are cruising, go away from all noises...if you have a kat--watch kat--turn on water pressure at the breaker and donot turn on any taps. go to where kat is facing--he is probably facing the bathroom...lol. look under the bathroom sink. you may find a slight hissing sound in there--always go to where the kat is facing and looking. kat will tell you where the leak is before ye run out of water!!!! replace whatever is making hissing noise as that is your leak. goood luck and have fun....i dont know if borrowing neighbors kat would work-----also check the hot water heater--they develop leaks at the corners, usually behind the things where no one can see them..so check the surface of the resting spot of the water heater--if you see any darkness to wood or any water, there is your leak--hot water heater----of course the leak may be under the galley sink--have you recently placed a pur or other water filter in your system>? i ask as the pur seems to make the pump come on when the water is not in use and the breaker has been left on......and there is always failure if the connectors--they are only plastic and they crack after a while--lol
for real--if you have a kat--watch the cat when you turn the breaker for water back on and listen hard. watch the kat--he will face the hissing sound--a kat will never turn his back on an enemy=hissing comes from enemies--lol---water leaks hiss.....follow the kat's eyes.......mine was 2 inches below sink in the head..lol.....on my friends boat was under galley sink......kat found them both before the hissing sound was audible to humans...saved a lot of water.....i dont know if a dog would do same thing-----


ps--donot ask me how i know all this!!!!!! lol--btdt since 1990--LOL--have fun....

[Hud3]

Another possibility...

Does your pump come on every time you turn on a faucet? If your accumulator is functioning properly, you should be able to run a faucet for a minute or so before the pump comes on.

If the bladder in the accumulator has lost all it's air, you won't have any reserve pressure in the system. What you're hearing could possibly be the result of a "water hammer" effect. The air in the bladder provides a cushion for the pump to pump against, since water is incompressible, but air isn't.

Try pumping up the bladder with a bicycle tire pump and see if that helps.

[Nightowl]

Thanks to everyone for your thoughts and suggestions. Never thought of using the neighbours cat I have to admit. Don't have a cat or a dog - best I could probably find at short notice would be a vagrant cockroach but I don't think he would have an ear for a hiss. Worth a try! LOL

Our boat is berthed at a marina 2 hours away so I will take your collective advice onboard when I go there this weekend and try to sort something out.

The pump is a small 'Johnson'. It does come on immediately when a tap is turned on but that is the way it has always worked. It doesn't seem to have a reserve.

Some suggestions certainly ring true as possible causes. I'll tackle it again this weekend.

Cheers

[zeehag]

do check under the sinks and all the connectors and collectorand hot water heater---lower corners on that thing----goood luck and may ye find the leak befor eall the water hisses out-by the time i could hear the hissing noises, the leak was huge and lotsa water was coming out under the sink in the head.....is fun to chase leaks...goooodluck ....

[theonecalledtom]

I had an air leak coming from the seal in a filter plumbed in for a drinking water hand pump faucet (plumbed into the pressure system).

No water leak, and it would trigger the pump about every two hours with no background rumbling but perhaps worth a thought if you are looking for leaks (in this case found by switching off different parts of the water system and waiting for the problem).

[divingmikeboats]

Nine times out of ten it's a slow drip somewhere in the system. If you have a shutoff at the pressure side of the pump close it.. If pumps stops cycling it's a leak in the plumbing. I have also had bits of junk from the tank get caught up in the rubber valves of the pump and allow pressure bleed off back thru the pump. If pump cycles with valve closed that is likely the issue. I hate pumps.

[Mermaid]

I have the same problem! Some water comes out of the faucets, then air, then some hot water, then lots of air then the stream stabilizes. If I turn the faucet off before this crazy cycle occurs- the pump does not shut off. Obviously air somewhere. Hope we can figure out how to find where it comes from. If we resolve it on Monday (the mechanic is coming) I will share with all.

[donradcliffe]

The rumbling and failure to shut off sounds like air in the system. Sometimes it is just a case of turning on all the taps full and letting it work itself out. If that doesn't solve the problem, take a hard look at the supply piping to the pump, especially if it ever goes above the level of the water in the tanks. Look at connections, filters, and valves.

[rwidman]

Originally Posted by Hud3

Another possibility...

Does your pump come on every time you turn on a faucet? If your accumulator is functioning properly, you should be able to run a faucet for a minute or so before the pump comes on.

If the bladder in the accumulator has lost all it's air, you won't have any reserve pressure in the system. What you're hearing could possibly be the result of a "water hammer" effect. The air in the bladder provides a cushion for the pump to pump against, since water is incompressible, but air isn't.

Try pumping up the bladder with a bicycle tire pump and see if that helps.

Some pumps are designed to be used without an accumulator tank. Mine is one.

The pump has a check valve somewhere, usually internal to the pump. You don't pressurize the tank, you pressurize the water lines. Without a check valve, the pressure in the lines would go to zero as soon as the pump shut off.

If you don't have an external leak, the internal check valve could be leaking back into the non-pressurized side causing the pump to come on and restore pressure.

You can buy a repair kit or a new pump. The new pump is about twice the cost of the repair kit and is far easier to install. Another choice is to install an in-line check valve in the water line as close to the inlet side of the pump as possible.

As for air in the lines, run water from each outlet (hot and cold, don't forget a transom shower) until there is steady water flow, no pulsing or air.