Water Pump changes water pressure

[John Bailey]

We've noticed that if we leave the water running, like to take a shower or to water the garden, that there is a big change in water pressure. When watering the garden, there will be plenty of pressure for about 5 min., then it will lose pressure, almost down to nothing, for about 5 min., then back up again.

Anyone know what's going wrong?

John

[Lee Schierer]

It sounds like your pressure tank is failing. The pressure tank should keep the water pressure in a range (usually 40-60 psig), giving some volume, depending upon the size of the tank until the pump runs. Then the pump should switch on at the lower pressure setting and run until the upper pressure setting is reached, which may not occur until the water is shut off if the pump has less capacity than the water being taken from the system at that time.

[John Fricke]

yup, pretty sure Lee is correct. If you have a bladder style tank the bladder is likely failing. If you have an older style tank without a bladder it probably needs charging with air. I remember having to help my grandfather charge his on occasion but I don't remember the pressures he used.

[Randy Cohen]

you use the pressure that your pressure switch is set for. if 60lbs, then pressure up the tank to 60 lbs. I think that your tank may be fine....you are going to get anywhere from 40 to 60 lbs of pressure...that would be a noticeable difference.

[Jerry Bruette]

Could be your pressure switch not working properly. Every time the bladder in my tank would fail the pump would turn on and off in rapid succession.

Both times I replaced my tank the directions said to pressurize it to 2# less than the low setting on the switch when the tank is empty. Example switch set at 40/60 then pressurize tank to 38#.

If you depress the stem on the air valve and water shoots out it's a sure sign that your bladder is leaking. On the tank that is:)

Good Luck
Jerry

[Terry Achey]

A water logged tank (bladder or not) will generally cause your pump to run just about every time you open a faucet because you have an absence of air. You cannot build pressure when you have an absence of air in the tank bladder (or non-bladder tank) and therefore the pump will often short cycle on-off as mentioned by Jerry. I wouldn't rule out a faulty pressure switch in this case.

Check the tank pressure with a tire gauge and watch the gauge while running the hose. If the pressure rises and falls erratically you probably have an air problem. If the pressure stalls at the low end and then kicks on and builds up the the high limit gradually, you problem have a faulty pressure switch.

Most pressure switches for residential pumps are factory set at either 20/40 psi or 30/50 psi. 40/60 is the exception.

Good luck with the repair.

Terry

[Mike Cutler]

John

I'm assuming that you have a well pump.
As others have suggested, your tank may simply need to be charged, repressurized, or at worst replaced( ~ 300.00 total if you do the work yourself). Do an internet search on Well X-Trol and you can find the basic info for recharging the tank reagrdless of manufacturer. If you can't remember the last time you charged it, this is a good 1st step to take.
This system is a basic on/off system that cycles off the pressure switch alone, but there are others that have a controller with an interposing relay which a little different.
There are some other possibities. Depending on the depth of your well itself you may have a multistage pump and one, or some of the stages are failing which would require a pump relacement. Additionally if your well is at a very low water level the reserve volume and available head pressure would be significantly less which is causing the pump to work much harder.
The bladder in the tank may have a leak and your tank is "solid" now. Water, being less compressible than gas would cause the pump to short cycle which is bad because it can cause accelerated wear, significantly decreasing the life of your pump.
Another problem could be that you have a significant amount of sediment in the bottom of the tank which is decreasing the tanks ability to act as a surge volume.

The first thing that needs to be established is how much pressure are you developing, and where the pump cut on and cut off set too, and is it correct. For my house it is 40-60 psi.
Secondly is whether or not the tank is performing it's job properly. Is it solid, need charging, or full of sediment?
Thirdly is to time the recovery time of the pump, and find out of the recovery rate of the pump is greater than the demand. In other word when the pump cuts on at the low pressure value does it develop more pressure than the low setpoint or does it continue to drop.

I know this is a little long winded, but a pump replacement can cost a lot of $$$$, and there are a few things you can check and do yourself.