Installing a second pressure tank on water well system


Old 01-22-17, 08:21 AM
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Installing a second pressure tank on water well system

I have read a few posts about installing two pressure tanks on one well, so I understand that it is possible, and not terribly complicated, I am simply looking for details on how to plumb the second tank in.

My current setup is your typical 1" pipe from the well into the pressure tank with a check valve on the downstream end, pressure switch on the tank, and pressure gauge on the Tee. Everything works fine, I just installed a tankless water heater this summer so now instead of having 60 gallons of water at the surface (30 in the old water heater and 30 in the pressure tank) I now only have 30 and this winter have been losing water supply under high loads (running the dishwasher, washing machine and multiple showers within a few hours will cause the well to pump completely down and all water flow to the loads stops.)
What I am hoping for is to add a 119 gal pressure tank so that these high loads don't cause the well to pump completely down.

What I am looking for help on is what would be the easiest way to install this second tank? Should I leave the pressure switch and everything as is on the first tank, and simply plumb straight into the new tank? Do I need a second check valve? Should I have a pressure release valves on both tanks? Is there something I should know about syncing pressure in both tanks? I have read that both tanks should be set to the exact same precharge which need to be 2psi below cut in pressure.

Thanks in advance for your help.
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Old 01-22-17, 11:34 AM
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Welcome to the forums! You aren't looking to gain pressure, just volume, so it would be a simple matter of piping another tank in tandem with the one you have. No new pressure switch or other periphery would be needed. The pressure will be the same in both tanks once they equalize.
Old 01-22-17, 12:09 PM
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I'm not sure that will solve your problem. The pump won't run as often, but when it does it will run for longer so is just as likely to pump the well out.

Is the problem that your well is low producing? Or maybe your pump just needs to be lowered a few feet.

The way a low producing well is handled is to install a large storage tank...but a second pump is added to provide house pressure by pumping from the tank. Then the well is set to pump a little bit every so many minutes to replenish the tank. This extracts the maximum amount of water out of the well without pumping it dry.
Old 01-22-17, 12:49 PM
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I may have misunderstood. I thought you were running out of pressurized water, not total water. If you are losing total water, then what Paul said. Here in the mountains, some higher elevation homes have 200 gallon storage tanks elevated to where the water in them is under pressure once pumped in to them. It isn't 40#, but it replenishes the main tank well enough.
Old 01-23-17, 08:58 AM
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Installing a second pressure tank next to the first is almost a no-brainer. It will improve the operation in the way of letting the pump run fewer and longer cycles.

Pre-pressurize the new tank in the same fashion as the old tank namely 2 PSI less then the pump turn on pressure.

If you are pumping the well dry so that air is being drawn in and spouting out of the faucets then the second pressure tank will not solve your problem. You would need to go to a two stage system described earlier, with the well pump filling a non-pressurized storage tank and a second pump wired to the existing pressure switches to work the pressure tank(s).

With a low yielding well the well pump will have to do what it does not like, run short cycles although with longer wait times in between (controlled by a timer) to let the well recover. This would have to on for a long period including most of the overnight if needed to refill the storage tank.
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