Pressure differential from well submersible pump

[Rjh2o]

I have a 4" 110ft well (PVC casing, 30ft static water level, pump is set at 80ft) with a 1/2 HP submersible pump, 40/60 switch and a well X-trol 302 bladder tank (set to the proper pre-charge pressure, 38psi).

At times I experience a water pressure differential that seems to be about 7-10psi drop throughout the pump cycle. I have not noted exactly the conditions when this occurs though. This happens with my outside spigots as well as household treated water.

Can atmospheric conditions affect the static and dynamic water pressure or flow rates from a submersible well or the static air pressure in the bladder tank?

So can anyone explain this phenomenon?

I don,t want a long drawn out debate over this. So I would ask any experienced well installers for their opinions.
Thank you,
RJ

 

[Valveman]

If you don’t want a long, drawn out debate, you shouldn’t ask for opinions from experienced “well installers”.

Anyway, you will need to give us a little more information. Do you just think the pressure is 7-10 PSI lower than it should be? Have you looked at the pressure gauge to make sure it is doing 40 to 60 like it should?

I don’t think it could have anything to do with the static water level or atmospheric pressure. But it could have to do with your “dynamic” or pumping level in the well. From 32’ that pump can pump a lot of water at good pressure. But if you use a lot of water and pull down the level in the well, at 100’ that pump can’t do much.

The drop from a static level of 32’ to a pumping level of 100’ equates to a 30 PSI loss in the house.

 

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[Rjh2o]

The 40/60 switch is working properly and gauge is working properly. I get over 20gpm from well.
The static water level is 30', Pump is set at 80'. So I would agree that draw down in the well could be an issue, but I have noticed this problem much more this year, which has been a very wet year. Water table is very high this year. So the draw down premise may be plausible. How many gallons of water would there be in that 50' column of water in a 4" well (static water level to pump)? What is the equation used to determine the PSI loss with well draw down as you stated above?
Yes I have looked into a cycle stop valve option.

Thank you,
RJ

 

[Valveman]

Assuming your 1/2HP pump is a 10 GPM series, it can build a maximum of 96 PSI. 80’ of lift equates to 35 PSI. So if you pull the water level down to 80’, the pump can only deliver 61 PSI at the surface. That is way to close to use a 40/60 pressure switch, 30/50 would be safer, unless you know for sure the water level isn’t pulling all the way down.

4” casing is about 1 gallon per foot, so 50 gallons stored in 50’ of standing water.

Even with a 30/50 switch, a 40 PSI CSV will make it seem like much stronger pressure in the shower, because it will keep the pressure at 40 for as long as you are in the shower. Without a CSV the shower pressure goes from 30 to 50, 50 to 30, 30 to 50, on and on for as long as you are in the shower, which makes for weak pressure in the shower.

 

[Rjh2o]

Thank you Valveman, I appreciate the explanation.
That makes sense and helps explain the pressure differential I have been experiencing. I do have a 40/60 switch currently so I will switch back to the 30/50 and install the CSV.
Greatly appreciate your help,
RJ