Hi,
We have city water, but when bought our house, they left an old well set up in the basement. Other then the outgoing pipes capped off, everything still works.

There is a pipe coming from outside into the basement.
It leads to and older 1/3 HP pump with an ON/OFF switch.
It's connected to a large steel expansion tank with an air inlet on a pipe on the bottom and a pressure gauge on the top.
There is another pressure gauge by the hose connector over the pump.

I hooked up a hose to it and turned the switch on. The water flows freely at a rate of 4+ gallons per minute, but the PSI is at 28. The motor NEVER shuts off. The water is very rusty.

I'm considering turning this on to save money for an irrigation system only.

Is it worth it?
How can I raise the PSI to at least 40 PSI?
How can I get the pump to cycle on and off? Otherwise my electric bill will be crazy.
How do you get rid of the rust? Just run it? How long?
How do you adjust the air pressure in the expansion tank?

If all of this is not worth the money or effort, PLEASE let me know.
Thanks
Joe

You should have a pressure switch on the system which turns the pump off and on as water is used and the tank pressure rises and falls. This site tells you about that. If you don't have one, it can be added for thirty bucks or so if you know a little something about plumbing and a little more, perhaps, about electrical wiring.

How to adjust water pump pressure, pump cut-on pressure and pump cut-off pressure - private pump and well system do-it-yourself repairs (http://www.inspect-ny.com/water/WaterPumpAdjust.htm)

I am guessing that your reference to an air inlet was probably the pressure relief valve. Also, if the well has not been used in a while, there is probably some rust built up in the tank and pipes. Run it until the water clears up. Might take a few hours.

As far as adjuting the pressure in the tank, you will first drain the system through a faucet until the pressure gauge reads zero. Then set the pressure at the valve at the top of the tank to 2# below whatever the minimum pressure (where the pump will cut on) is that you will run the system at.

Thanks for the response. I checked the tank and I see a screw plug towards the top of the tank. I'm guessing I can remove this and install an air inlet to add pressure.

Is all of this worth it, or just replace the tank to a modern version?

OR...

Can I remove the tank entirely? Would I be able to increase pressure to 40 PSI by installing a larger circulating pump? How would it cycle on and off with the sprinkler system? It will ONLY be used for the lawn and nothing else, but I do need at least 40 PSI.

Thx
Joe

Sounds like you have a galvanized pressure tank and not a bladder tank. (Jlisenbe gave you instructions for charging a bladder tank). Pressure tanks work differently.
To recharge a pressure tank all you have to do is shut off the power and drain the tank. When you turn the system back on the water entering the tank will compress the air on top and that's all there is to it. Another way would be to induce air into the tank with a compressor through the snifter valve you already mentioned.
I would replace the control box with a 30/50 PSI setting and if the third horse pump can't pull it increase the pump capacity to 1/2 horse. How deep is the well that the pump's pulling from? Good luck, tom

If you have no plans for the pump other than irrigation, depending on what you intend to do for irrigation you might be able to simply do away with the pressure tank and just use the on/off switch. If, for instance, you intend to run a few sprinkler heads, then I would at least try just hooking up directly to the sprinkler line. Keep an eye on your pressure gauge, but it doesn't sound like your pump is going to get much over 30 or 40 pounds anyway. As I said, it just depends on what you plan on doing for irrigation.

SB is entirely correct in his comments, but bear in mind that the old galvanized tanks had a means of recharging the air in the tank every time the pump cut on. In your case, unless that is set up and working, your tank will eventually fill with water and become ineffective. Of course you can simply recharge the air every two or three months manually as he described if you want to go to the trouble.

Good call jlisenbe!
If he just had a few sprinkler heads manual operation would be the simplest way to go.
However, we were both negligent in not asking asking exactly hat he's talking about when he says, "irrigation system". Is this a sprinkler system or a open trough irrigation system? If a sprnkler system does it have zones? What kind of volume will it take to operate this system and how many sprinklers will be on line at one time?
We just don't have enough information to make a call. Regards, Tom

I agree completely. Surkurf might be able to handle this fairly easily. I can tell you this. Don't plan on running 6 or 8 sprinkler heads at one time.