Pulsating water pressure and low cold water pressure


Old 01-17-11, 08:07 PM
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Pulsating water pressure and low cold water pressure

For a couple of weeks now I have had pulsating water pressure on both the hot and cold side of every fixture in the house. I also have very low water pressure on the cold side at the clothes washer and the toilet. I have a private well that the pump was just replaced about 6 years ago and a bladder tank that was just replaced about 3-4 years ago with a 55 gal hot water tank that is about 6 years old and seems to be working fine. I do have a pressure gauge on and have noticed as soon as any water is turned on the gauge goes up and down erraticly. Also noticed when flushing the toilet it sounds like a wind storm in my pipes until the toilet tank refills. Can anyone please give me some advice?
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Old 01-17-11, 08:35 PM
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Sounds like your pressure tank is bad. Check it like this....

Bladder Type Water Storage & Pressure Tanks - Diagnosis & Repair
Mike NJ
Old 01-17-11, 10:37 PM
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The noise the toilet and it's supply piping are making will probably disappear once the cause of the pressure fluctuation is corrected.

The fill valves on toilets don't use a rubber washer the way traditional faucets did. Instead, a toilet fill valve will have the house's water pressure acting on both sides of a rubber disk, but the area exposed to that same pressure is different on one side of the disk than the other. Since force is equal to pressure times area, there will be a net force pushing the rubber disk against a seat when the toilet tank is full, and there is no water flow into that seat, and subsequently on into the toilet tank.

When you flush the toilet, the float drops and that motion causes a plug to be pulled out of a hole which allows the water pressure to escape on the large area side of the disk. The result is that the water pressure on the small area side of the disk pushes the disk off the seat, and allows water to flow into that seat and on to the toilet tank.

When the tank is full again, the float rises and re-seals the hole on the large area side of the disk. The difference in net force on both sides of the disk then pushes the rubber disk back onto the seat to prevent further flow into the toilet tank.

So, the flow of water into the toilet tank is dependant on the pressure of the water in the supply piping to the toilet. If you have a fluctuating pressure in that supply piping, you can have the rubber disk lifting off it's seat only to be pushed back down as the pressure equalized on both sides of the disk, and that can cause the toilet fill valve and supply piping to vibrate and make a noise like a flute or a fog horn or anything in between.

So, the problem with the toilet will very likely clear up once the problem with the fluctuating pressure is corrected.

The pressure at the washing machine should be the same as everywhere else, so I suspect the strainer washers in the flexible water supply lines to the washing machine are clogged up with dirt.
Old 01-20-11, 07:45 PM
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Thanks for the advice. I did check the tank and as soon as I touched the air valve water came out so I guess my tank is water logged. Good news is that I was wrong and the tank is only 2 years old and has a 5 year warranty so I am going through the company for a replacement tank. Thank you for taking the time to give advice and help.

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