My question is how does an expansion tank work with a well pump and how do I install it into the well pump system I have now? I manually turn the pump on and off. However, I understand I can enable the pump to operate automatically if I install two things a relay and expansion tank. I understand the relay work with the expansion tank to sense pressure drops, but can you explain it in more detail as to how rely, expansion tank and pump work and what size expansion tank I would need. My present well pump is a 3/4 hp motor use to water a lawn which does OK manually. Thank you for your help in this area.

Very simply, an expansion tank is just a closed container for the pump to fill with water. As the water fills the tank, the air inside it gets compressed until the pressure is high enough to trip the pressure switch off. Usually 40 to 50 psi. When enough water is used to lower the pressure by about 20 psi the pressure switch turns the pump back on and the cycle repeats.

It would seem to me that you already have a pressure tank and switch in your system unless there are no valves between the pump and the lawn sprinkler. With a 3/4 hp pump, unless something is seriously wrong with it, there isn't any garden hose that I've seen that wouldn't burst when you shut off the flow with the pump running! :eek:

The expansion tank is usually located close to where the well pipe comes into the house. A small one, which would seem like all you need, is maybe 18 inches in diameter and 30 inches high (more or less). They are sized to the demand of the location. Manufacturers supply tables to help. The tank, pressure relief valve (REQUIRED), pressure switch and (optional) pressure gauge are all located on a T-shaped manifold which has the well line coming in one side and the house supply out the other. These parts are purchased along with the tank.

EPM

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Originally Posted by HandyMan OHara

My question is how does an expansion tank work with a well pump and how do I install it into the well pump system I have now? I manually turn the pump on and off. However, I understand I can enable the pump to operate automatically if I install two things a relay and and expansion tank. I understand the relay work with the expansion tank to sense pressure drops, but can you explain it in more detail as to how rely, expansion tank and pump work and what size expansion tank I would need. My present well pump is a 3/4 hp motor use to water a lawn which does ok manually. Thank you for your help in this area.

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You need to look into a bladder tank. This is a tank with two compartments, the top is a rubber bladder that has some air pressure in it, around 30 pounds. The bottom is just a tank that holds the water. As the pump pumps it pushes water into the bottom portion of the tank, as it it filling it also puts more pressure on the bladder in the tank.

From there on it works like Topic Review explained above.

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Originally Posted by letmetellu

You need to look into a bladder tank. <snip>

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Do they even make tanks without bladders any more for private well applications? I didn't want to complicate my explanation by adding those details, but yes, that's the only way to go.

EPM

Definitely need the tank and pressure switch. Just asking for problems without them. If you have ever forgotten to turn a light off while going on vaction for a week, then you could very easily forget to turn off your pump. Wouldn't be good.

My pump turns on and off frequently; the PSI barely drops before it switches on during use. Is this an air pressure issue or some sort of setting on the pump? How can I fix it? Thanks!

Could be a couple of things. I will give the most likely ones.

First check the pressure gauge and see if the cut-in and cut-out pressures still differ by about 20 psi. If they don't (and the pressure gauge is functioning correctly, a big IF), then I would suspect the pressure switch, but keep going.

If it appears that the cut-in/out pressures are correct, then I would suspect a waterlogged pressure tank. (This actually is the most likely, but you have to do that other check first.) That happens when the bladder in the pressure tank fails and the air that is supposed to be in there is absorbed by the water. As the air volume in the tank decreases, the volume of water required to change the pressure over the cut-in/out range becomes smaller, hence the rapid cycling. To test this, turn the pump off, make certain nothing in the house is using water (shut off the main valve) and drain the pressure tank until the WATER pressure reads zero (you DO have a tank drain don't you?). If the tank still has water in it (often you can rock it slightly to tell but BE CAREFUL) it most likely needs replaced. Then check the residual AIR pressure in the tank. It should read 2 psi less than the pump cut-in pressure with the tank empty. If the bladder is ruptured, it will read the same as the water pressure which is zero (right?).

When you replace the tank, you can reuse the manifold if it is a modern one compatible with the new tank, but REPLACE THE PRESSURE RELIEF VALVE with a new one. Also replace the pressure gauge if it is old, and the pressure switch if it is old too. And DON'T cheap out and use a galvanized nipple on the pressure switch, especially with a brass manifold. I've seen dangerous overpressure situations when that steel nipple corrodes closed.

I've already written too much, so I'll let you work on this. There are other things too, but they often are a bit more system specific and I can't see your system from my keyboard.

Have a happy new year.

EPM

When installing a bladder tank should you plumb pipes from the pump to the tank first and then to the main water pipe to the house.

You usually use a "T" fitting to do that. Bladder tanks typically have the pipe fitting at the bottom. See link below. With that T, you will put a 90 degree elbow at the end of the long run to go up to your tank.

Brass Tee for Pressure Tank Installations - 1" x 11" MPT Connection - T-1x11-M

Pump motor is cycling too often. Is this from expansion tank pressure?

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Originally Posted by 1chase

pump motor is cycling too often. is this from expansion tank pressure?

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Let's recharge your bladder tank. Shut the pump off at the breaker box and open a cold water tap to bleed off the pressure.
You will see a air valve on top of the tank. The PSI on the bladder tank should be 2 PSI UNDER the cut in point on the control box. In other words if your pump cuts in at 30 PSI the tank should be charged at 28 PSI. Here's how bladder tanks work, (see image) Good luck, Tom