Ok, I just bought a new house, it has well water and I'm new to all this pressure tank and submersiable pump stuff. I just replaced the pump because the old one died. I noticed at the well head that when the water was running the pump would cycle very quickly, it would reach 50 psi turn off then lower to 30 psi and turn back on in a matter of seconds. I had a 20 gallon pressure tank installed and now it cycles up to 50 and back down to 30 in about 4 mins. I'm not really sure if that is typically or not? I used a tire air pressure gauge on the pressure tank and it shows it is at 28 PSI which is 2 PSI below 30 so it should be correct right?

When no water is running the PSI stays at just below 40 PSI, does this mean my pump is constantly running? If so how can I fix this?

 

There is a sticky here http://www.doityourself.com/forum/we...well-info.html

that I think you will find of value. In that sticky I added a comment that explains what you should see and hear in a normal cycle. If it cycles when there is nothing being used then there is a leak and we need to find it. We can help you find it.

A 20 gallon tank is way too small. I realize they sell these at the Big Box Stores as something that will work, but it is just too small. A 20 gallon tank set at 30/50 means that only 8 or so gallons is held in reserve. A flush or two and a kitchen sink of dishes means it will run out and cause the pump to run.

More than that is better. A 50 gallon tank means about 20 gallons of water in reserve and even that is too small for a 3 bedroom house with teenagers that like to take long showers.

A 50 gallon tank is the absolute minimum even for a house of 2 people. For more people, add more gallons knowing that 60-70% of those gallons will be taken up by air.

 

So I assume since the pressure isn't reading 50 PSI on my gauge (Its just slightly under 40 PSI) that the pump is just continuously running when the water is off?

If thats the case can I just move the pressure switch down to under 40 PSI so it will cut off and then release air in the pressure tank till it gets to 2 PSI under 20 PSI and be good to go?

 

Hi Girard –

I’m a newbie to wells myself, and I don’t want to confuse the issue. Vey knows a lot more than me about this stuff.

But are you saying you have a pressure gauge out near the well head? Is your pressure tank outside near the well head then? Your pressure gauge should be at the piping very close to the pressure tank to get an accurate reading.

That doesn’t sound right (to me anyway).

Your pump should shut off at 50 psi. Then you continue to use water – which isn’t much in the 20 gal tank. When you drop to 30 psi the pump will come back on. I think in a 20 gal tank you only have a drawdown of about 6-7 gals of water at the 30-50 psi range. (The rest of the volume in the tank is air as Vey said).

So in other words, the pump fills the tank and stops at 50 psi. You then use 6-7 gals of water from the tank and the water pressure is then down to 30 psi and so the pump comes on again. As you continue to use water the pump is running and servicing the demand at whatever location(s) you are using for the test (hose(s), faucet(s), whatever). So some of the pumped water is coming out to the hose, faucets, whatever, and the rest of the water that is being delivered from the pump is pushed into the tank. Eventually the tank pressure reaches 50 psi again and the pump then shuts off again and the whole cycle repeats.

So you can see that these on-off times will vary depending on how much water you are using at the hose or faucet or whatever, the tank size, and gals/min capability of the pump.

I believe, for example, if you had a pump that could deliver 9 gals/min, and you were using, let’s say, 7gals/min at the hose, faucets, whatever, then you would only be putting 2 gals/min back in the tank as the pump ran. So in that case it would take 3 minutes pump time to get the tank pressure back to 50 psi and the pump would shut off (assuming your tank drawdown was 6-7 gals as assumed above).

It would then take a minute or less to use up those 6-7 gals from the tank (because you are still using 7 gals/min at the hose, faucets, etc.) so your pump would come back on in less than a minute, the cycle repeats, and then as described above it takes 3 minutes pump run time again to fill the tank, and so on.

So you can see it’s complicated (to me anyway, LOL), and I think you need to run a controlled test and you will have to know how many gals/min are being delivered at the faucets, etc when you run the test.

But I think as Vey says a 20 gal tank is too small. Let’s say in the above example you were running a shower at 2 gals/min, then your pump comes on at 30 psi, 2 gals/min then continues to go to the shower, and the other 7 gals/min goes into the tank , so it only takes a minute or less to fill the tank back to 50 psi and the pump shuts off. You would have a lot of pump short start-stops, and start-stops are (if I’m not mistaken) what mainly determines the life of the pump.

HA! I just re-read Veys post, and he said about 8 gals in reserve in a 20 gal/tank , so I wasn’t too far off when I said 6-7 drawdown in the example above.

But you did say it reaches 50. Does that mean it drops to 40 very quickly when it reaches 50?

 

Pictures, Pictures, Pictures

Vey pretty much covered the important things, but as someone who learned about his well and filters in a hurry (my system saw no love from the previous owners), I can probably give you a few pointers from a newbie.

First things first, your tank is pretty small. I have a 50gallon and it's a bit small for our house.

Secondly, with an already installed (potentially older with new pump) system, don't trust your pressure gauge, specially if it's connected on unfiltered water. Replace it. They are only ~$10 at the local mom and pop hardware store.
Mine looked like it was working correctly until I drained and flushed the iron and junk out of my tank. With no water and the valve at the gauge open, I was still reading pressure.

Pretty much the rest as been covered by the others.

 

Ok I see what your saying...I have a pressure gauge and switch at the well head and then a pressure gauge in the basement which is where the pressure tank is.

Yeah it looks like its working but Pressures still seem to be running funny though and now I feel ripped off cus the guy I talked to said a 20 Gal. would be fine also said that they wouldn't have to move the pressure switch from the well head. Looks like I wouldn't be doing business with those plumbers again.

 

I think that's great advice. Completely forgot about that. I had a bad pressure gauge and I was running in circles, nothing made sense until I replaced the gauge.



Exactly what happened to me!

 

I have replaced both gauges same story.

 

Wait. You said that the pressure switch is at the wellhead and the tank is in the house? How can that be? Is there some sort of long hose connecting them?

The tank and the pressure switch are connected with a little tube (some times copper tubing). The pressure switch "feels" the pressure through the tube and reacts to it. The gauge is there just for you. Sometimes that tube gets plugged up and then the pressure switch stops acting right because it doesn't feel the correct pressure.

When ever you put in a new tank, it MUST be set up from scratch. See that sticky how to do that. Do it.

 

Your pressure tank is too small.
Did you pre-charge the tank before turning on the well?
It should have 20psi air in it prior to turning on the pump.
You need more pressure tank capacity. you can still use the one you have, but I recommend picking up a much larger tank. I recommend a total of at least 100 gallons in pressure tank (or tanks) capacity. this will cause your submersible well pump to cycle less and last a lot longer. The bladder tanks, do not seem to last as long as Galvanized ones, but the bladder tanks are more convenient. I converted Ocean Bouy's into pressure tanks, very cheap but may require some adaptions. My smallest are 500 gallon capacity and my largest are 2150 gallon capacity. I just have a compressor hooked to then and throw a knife switch whenever they need some air. my 500 gallon bouys are 34 years old and still going strong. My system is at a trailer Park. So I need more capacity, I have 41 spaces, with a total of over 8,000 gallons of pressure tanks. My well pump does not have to work very hard. The only reason I have so many tanks is I got them really cheap (less than $2000 total) and figured, you can never have too much in pressure tanks.

 

You can leave the existing pressure tank there and add another, larger, pressure tank.

The existing pressure tank, assuming it was precharged correctly and does not have a bad bladder, will continue to contribute to the well being (no pun intended) of the system.

The pressure switch(es) used to turn the pump on and off do not need to be near the pressure tank. The sensing tube can connect to a pipe and sense water pressure equally effectively compared with connecting to the top of a pressure tank and sensing air pressure. The best location for the sensor tube tap-in for the pressure switch(s) is where the pressure does not bounce (oscillate) rapidly; I don't know where that best location is.

Meanwhile a second pressure gauge at the top of a pressure tank can help in tracking down system problems. Having a pressure tank gauge bottom out well above pump turn on pressure indicates that the pressure tank needs some attention.