Well system pressure tank sizing

[autojoe]

I have a well system 220 feet submersible goulds 1/2 horse pump 20 gal tank 20/40 pressure switch set to 30/50. My water pressure seems low. What I wanted to do since pressure switch was old was to change to a 40/60 switch but didn't know if my 20 gal tank was big enough with increased pressure. How big of a tank do I need and 60 psi too high. I have all new copper water lines. Thanks in advance for your help. Joe

 

[autojoe]

Sorry goulds v100 32 gal tank.

 

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[Reach4]

New pressure tank will not increase pressure at the taps. It affects how often the pump has to run.

When the pump runs, how long does it run at minimum? Does the gauge rise noticeably slower as it approaches 50?

Anyway, your minimum pressure tank size should be enough to let the pump run for at least a minute. If your pump supplies 5 gpm and you have your air precharge right, the pump would run about 1 minute. A 20 gallon tank supplies about 5 gallons of water before the pump needs to run again. Don't let me talk you out of a 32 or 44 gallon tank, but it would not increase your water pressure. You may need a 3/4 HP 7 gpm pump to give the pressure you want.

Do you have a cartridge filter or other filter? You might get a garden hose thread pressure gauge to check pressure farther along while you use water. You can hook such a gauge to a laundry tap or the drain on the water heater. Also, it can serve as a check for your water pressure gauge.

 

[LLigetfa]

A 1/2 HP pump in a 220 foot deep well could deadhead at 60 PSI depending on the water level at the time. Keep in mind that water level may vary depending on rate and length of draw.

You should look into a CSV (Cycle Stop Valve) for constant pressure before raising the pressure switch cutout. If the well produces less than you draw, a larger tank is seen as an additional load as it fills at the flow rate the pump can produce, not at the rate you use unless you use a CSV.

 

[Reach4]

You should look into a CSV (Cycle Stop Valve) for constant pressure before raising the pressure switch cutout.

A CSV with that pump would be counterproductive.

 

[autojoe]

Pump runs several minutes like 3-4 minutes before it shuts off. Pressure builds steady. I have lots of calcium in water and hot water tank. I have grade L copper. Wonder if mineral deposits in lines. Was thinking of converting to pex. Pump man when changed pump originally had goulds 1/4 hp and I told him put bigger tank and 1/2 hp pump. Going to get gauge for hose bib check pressure. Pressure seems higher from utility tubs and bathtub then kitchen and bathroom sink. Thanks for all advice.

 

[Reach4]

I am not aware of any 1/4 HP submersible pumps for going down a well.

In selecting a pump for an application, the depth to the water is what is important, but not just the depth when water is being drawn, but also the depth that it pumps down to during use. It is still good to know the "static level" -- the depth the water is when it rests-- when selecting a pump.

Calling a pump by its horsepower is only part of the story. The gpm rating is important too. A 1/2 hp 10 gpm pump cannot develop as much pressure for normal household use as a 7 gpm 1/2 hp pump can. A 10 gpm pump is usually cheaper than a 7 gpm pump because it has fewer stages.

Did this pump give good performance for you when it was new, and then got worse? Or was it like this pretty much from the beginning.

Pump runs several minutes like 3-4 minutes before it shuts off.

I was not expecting you to say that. Your problems will not be helped by a new pressure tank. Three to 4 minutes for a 20 gallon tank is unheard of unless you do have a CSV. But if you had a CSV, the pressure would build much more slowly in the second half or so of the pressure rise.

Pressure builds steady.

That's a good sign. We would not want the pump running out of oomph as it approaches the cut-off pressure.

 

[Jadnashua]

The pump killer is frequent, short cycle times. Well, running out of water can do it as well as pumping a lot of sand.

A larger pump, if your well is a low recovery one, won't help.

 

[autojoe]

I checked the old pump was 1/2 hp I wanted 3/4 hp. Pressure good in utility tub and bath tub. Maybe calcium deposits in the copper lines. Thanks for the reply.

 

[autojoe]

The pump 3/4 hp goulds is 10 gpm. It takes awhile to kick on. May take 4 to 5 minutes to shut off. The pressure seemed higher before mainly from kitchen faucet and bathroom faucet.

 

[autojoe]

What do you mean by short cycle times. It takes awhile to go from 50 pounds to cut in pressure of 30 psi. Then takes 4 minutes to get back up to 50 psi.

 

[Reach4]

The pump 3/4 hp goulds is 10 gpm. It takes awhile to kick on. May take 4 to 5 minutes to shut off. The pressure seemed higher before mainly from kitchen faucet and bathroom faucet.

Pump may have deteriorated. The path to the pressure switch may be partially blocked.

In addition to those other places, the garden hose thread pressure gauge can go on the drain valve at the pressure tank.

It takes awhile to kick on.

Focusing on that, are you saying that the pressure can go below 30, and it takes a while for pressure to start rising? So is there a delay between when the pressure switch clicks and pressure starts rising? Or is there a delay in the pressure switch clicking?

If the pressure switch clicks late, that could be caused by a clogged nipple to the pressure switch, so the pressure switch does not detect the low pressure right away.

How long has the current pump been in service?

 

[Valveman]

A 32 gallon tank only holds 8 gallons of water. Your 1/2HP pump should fill that tank in 30-40 seconds. When you get the pump back to working properly, then you will have short cycling problems as 30-40 seconds is not enough. A Cycle Stop Valve will solve that problem, and if your tank is bad, you can replace it with a 4.5 gallon size as comes in the PK1A complete pump control kit.