High pressure at well (90-100) 40-60 at house

[Lamar]

I am experiencing water pressure in the piping at my drilled well of 90-100 psi. I have a new 36 gal diaphragm pressure tank at the well for extra storage for use with livestock watering and small amount of landscape watering. I fear the amount of pressure is going to rupture the diaphragm of the new tank. I hooked it up but after seeing the high pressure, I installed a ball valve and now have it temporarily off line until I get this figured out. There is a 75 psi pressure relief valve "adjusted" by pump installer to accommodate the 100 psi

Here's what I've got.

Well- 280' depth with 20-25 gpm. 6" casing drilled 30 years ago

New pump installed 3 years ago. 1 1/2 hp, 20 gpm set at 160' with 1 1/4" sch 120 pvc, 10-3 w/gnd

30 year old WelXtrol WX252 86 gal pressure tank in basement of house. New A.O. Smith 36 gal pressure tank in masonry well house. (This just replaced a 10 year old one due to diaphragm gone bad and leaking)

240 ft of 1" pvc from well to house. House tank is approx 12' higher than well.

Pressure switch is at house tank and is 40/60.

Here are my current cut on/cut off pressures.
At well using a hose bib gauge. Cuts on at 92 psi, off at 98 psi. (approx same reading when I had the pressure tank with gauge hooked up) Pump runs 64 seconds with no water running.

At house using gauge on line at pressure switch. Cuts on at 40, off at 60. Matches hose bib gauge approx 5 ft from pressure switch gauge.

So my questions are.
Is the 98 psi at the well to be expected? Can the Sched 40 and joints within the well house handle the pressure?
What's causing the apparent pressure drop between the well and house.
Is it advisable/safe to hook the 36 gal A.O. Smith tank back up? I see that it has a 100 psi max operating pressure.
If not, what are my options. The well house is an unheated masonry structure and is of a size that could house an 86 gal tank plus the 36. If you suggest I consider this, what would be involved relative to electrical and piping. Pressure switch size?
Will greatly appreciate your help.
Thanks,
Lamar in Athens, Georgia

 

[LLigetfa]

240 ft of 1" pvc from well to house. House tank is approx 12' higher than well.

240 feet away from the pressure switch is too far for a tank to be but does not explain the cut-in pressure. Gravity adds .43 PSI per foot so at the wellhead it should only be 5.16 PSI higher at cut-in.

 

[Sponsor]

 

[Lamar]

240 feet away from the pressure switch is too far for a tank to be

Not sure we're on the same page here or maybe I'm not understanding. The 40/60 pressure switch is at the 86 gal tank which is in the basement of the house which is 240 ft away from the well.

 

[Hedley]

You numbers are not lying. I calculated 27.21 psi friction loss + 5.19 for the elevation and 60 for the high side of the pressure switch. 92.4 psi at the well is an accurate guage reading.

 

[Hedley]

The at the well... Pump off.. pressure at the well should be 5.19 psi lower.
If you wanted to keep the smaller tank at the well it would stretch the diaphragm. Probably shortening the life of the tank. I would move it to the other location with the other tank.

 

[Bannerman]

After the pump has shut off for several minutes and no water is being used, does the pressure at both locations eventually 'equalize' so they are within the 5 psi differential due to the elevation difference?

 

[Reach4]

Is it advisable/safe to hook the 36 gal A.O. Smith tank back up?

No, not at the well house. You could put it at the house with short big piping.

Alternatively, insulate the well house with XPS or EPS foam insulation. Then put both tanks in the well house along with the pressure switch. Adjust the pressure switch to maybe 45/65, and set the air precharge to both tanks to 43 psi.

How cold does it get in your area? It probably doesn't take a big heater to keep an insulated well house above freezing inside.

 

[Lamar]

If you wanted to keep the smaller tank at the well it would stretch the diaphragm. Probably shortening the life of the tank. I would move it to the other location with the other tank.

I guess that could be an option however not much room in the basement. Would have to get creative with piping. The piping for the livestock and landscape irrigation is in and comes out of the well house so I guess I'd still have the high 95 or so psi there. Any problem with that?

 

[Lamar]

After the pump has shut off for several minutes and no water is being used, does the pressure at both locations eventually 'equalize' so they are within the 5 psi differential due to the elevation difference?

I actually noticed that it does, wasn't sure why but I get it now, thanks.

 

[LLigetfa]

After the pump has shut off for several minutes and no water is being used, does the pressure at both locations eventually 'equalize' so they are within the 5 psi differential due to the elevation difference?

The cut-in pressure then at the wellhead should be just 5 PSI off from the house but the OP claimed it is 91 PSI! While the tank at the house is being drawn down, there should not be friction loss at the wellhead since the pump would not be running before the pressure switch calls for water.

 

[Lamar]

Alternately, insulate the well house. Then put both tanks in the well house along with the pressure switch.

How cold does it get in your area? It probably doesn't take a big heater to keep an insulated well house above freezing inside

Very seldom gets in the single digits, below mid teens maybe once or twice a year. The house is built of old cobblestone from the streets of Athens Ga so stays pretty cozy. An extension cord and 100 watt light bulb has sufficed for all these years to keep the existing tank and piping from freezing.
If I did move the big tank to the well house, would I need to up the 40/60 to a 60/80 pressure switch to compensate for the 240' run of 1" pipe to the house.
Also as there is currently no electrical in the well house other than the switched pump wiring, is there a way to convert the 220 power to 120 for use with say a small heater.
Thanks!!

 

[Bannerman]

I suspect there could possibly be a partial blockage in the line between the well house and the pressure switch such as a partially closed or damaged valve, or blockage in a fitting.

Excessive pressure from the pump would also make sense if there is a CSV or PRV in the line between the pump and pressure switch.

 

[Reach4]

Also as there is currently no electrical in the well house other than the switched pump wiring, is there a way to convert the 220 power to 120 for use with say a small heater.

What size wire is the 240 volt line to the well house? If it is big enough, you could maybe put in a 240 volt subpanel, and power both the pump and a small 240 volt heater. Maybe not.

 

[Hedley]

I guess that could be an option however not much room in the basement. Would have to get creative with piping. The piping for the livestock and landscape irrigation is in and comes out of the well house so I guess I'd still have the high 95 or so psi there. Any problem with that?

 

[Lamar]

The cut-in pressure then at the wellhead should be just 5 PSI off from the house

So if I'm understanding correctly, there should only be 5 psi difference ? The 240 ft of pipe friction doesn't come into play?

I suspect there could possibly be a partial blockage in the line between the well house and the pressure switch such as a partially closed or damaged valve, or blockage in a fitting.
Excessive pressure from the pump would also make sense if there is a CSV or PRV in the line between the pump and pressure switch.

The only backflow preventer is at the wellhead and no other valves that I am aware of. A partial blockage of some sort could be a possibility I guess, tree roots compressing the pvc or blockage in a fitting as you mentioned. If that is the case then moving the 86 psi tank to the well house would not work then right?
Guess y'all can tell I'm beginning to get a bit confused here, but will keep trying to understand. Thanks for all the input so far!!!

 

[Lamar]

What size wire is the 240 volt line to the well house? If it is big enough, you could maybe put in a 240 volt subpanel, and power both the pump and a small 240 volt heater. Maybe not.

10 gauge

 

[Hedley]

You could use the tank in the well house if you got creative. Here is one way... The water going to the pressure tank would require an "in' and an "out". Going in you would need a water pressure regulator about 80 bucks or so. I work on wells I don't keep up with the "regulator" market. And on the output side put a check valve in to keep unregulated water coming in. Set the regulator to regulate at 60-65 lb and it shouldn't overpressure the tank.
I made a mistake before in an earlier post ... The pressure at well will be 5.19 PSI higher at the well when the pump is not running.

 

[Hedley]

10 gauge

Better use #8

 

[Hedley]

So if I'm understanding correctly, there should only be 5 psi difference ? The 240 ft of pipe friction doesn't come into play?
This is correct. Cramming 20+ GPM in the line is creating friction loss when the pump is running.
Here is a link to a friction loss calculator.
http://www.freecalc.com/fricfram.htm

I think the pressure switch and tank should be in the well house and you wouldn't be worrying about line pressure at the pump. Your demand at the house is probably not going to be excessive to worry about friction loss to the house.
Use a GSG square D pressure switch with a 50-70 setting and you should be good.
Really.. if you irrigating heavy a cycle stop valve would help your situation.





The only backflow preventer is at the wellhead and no other valves that I am aware of. A partial blockage of some sort could be a possibility I guess, tree roots compressing the pvc or blockage in a fitting as you mentioned. If that is the case then moving the 86 psi tank to the well house would not work then right?
Guess y'all can tell I'm beginning to get a bit confused here, but will keep trying to understand. Thanks for all the input so far!!!

 

[LLigetfa]

So if I'm understanding correctly, there should only be 5 psi difference ? The 240 ft of pipe friction doesn't come into play?

Friction does not come into play when the pump is not running which it shouldn't when reaching the cut-in. Only after the pump has started would the pipe friction show as an increase in pressure. So cut-in pressure at the wellhead should be 45 PSI, not 92 PSI.