Best location for pressure tank and switch

[Tedr]

My 3/4 hp jet pump draws water from the lake and is located about 15' above lake level. There is a 2-gallon pressure tank at the pump. This small tank was added two years ago to solve a water hammer/bounce problem. I haven't checked the air pressure in this tank lately. The pressure switch is attached to the pump. It is set for 30/50 psi cut in/out and the pressure gauge confirms this.

The larger water tank (2o gallon) is located at the cottage about 140' away on a hill. The vertical rise is about 100'. The air pressure in the tank is 28 psi. The pressure at this tank varies between 10-28 psi. This is barely satisfactory.

Before I invest in a submersible or a well, I would like to know if water pressure can be improved by moving the larger tank down to the pump house at the lake or moving the pressure switch up to the tank at the cottage.

Or are there any other options? Maybe a higher-pressure switch if available? A booster pump has already been considered and rejected.

 

[Reach4]

Before I invest in a submersible or a well, I would like to know if water pressure can be improved by moving the larger tank down to the pump house at the lake or moving the pressure switch up to the tank at the cottage.

Or are there any other options? Maybe a higher-pressure switch if available? A booster pump has already been considered and rejected.

You can hold the pressure switch engaged to see how high the pressure goes, while you watch. You can then set the pressure switch to turn off maybe 7 PSI higher than that. I am not sure if 7 is the right number. You definitely want the pump to be able to produce enough pressure to shut off, even after things fall off a bit.

Jet pumps can sometimes be fitted with a different jet to increase pressure at the expense of volume.

A pressure switch needs to be with the pressure tank. If you could move both up the hill, that could be better. It won't let you go to higher pressures, but it would help the pressure regulation be better.

For every foot higher after the pump, you lose 0.433 PSI. A foot before the pump probably loses more.

I am not a pro.

 

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[SuperGreg]

I am no expert, but just going by the physics of it putting the pressure switch at the top would cause it to cut in/out with the actual pressure tank pressure, not the extra pressure seen at the bottom of 100' of water in the pipe. If you moved the tank to the bottom, it would pump up to 60 psi but then you would lose 43 psi on the path up the hill and you'd be right where you started. Seems like the best bet would be to put the pressure switch at the top as long as the pump can develop enough pressure.

 

[Valveman]

It takes 43 PSI to make up for the 100' rise. So if you put the pressure tank/pressure switch at the top of the hill, you will get the 40/60 the switch is set for. If you have the pressure switch/pressure tank at the bottom of the hill, it would need to be set for 80/100 to get the same 40/60 at the top of the hill. Either way will work, but the pressure switch would be less expensive and the tank can be smaller when working at lower pressure from the top of the hill.

 

[Tedr]

Thanks for the helpful replies. I plan to move the switch up to the tank and will report the result after I get it done. Won't be there for another week or two.

 

[LLigetfa]

Either way will work

Are you sure? I don't know of any jet pump capable of 100+ PSI. A properly sized submersible can.

 

[Reach4]

Thanks for the helpful replies. I plan to move the switch up to the tank and will report the result after I get it done. Won't be there for another week or two.

Be prepared to use a lower pressure switch. Your jet pump may not be able to raise the pressure enough to reach 30 PSI at the top. So you might need to have a low pressure switch, and be prepared to adjust it downward further. You can force the pressure switch on with a plastic rod, and measure the pressure up top. Then make sure your pressure switch up top turns off the pump sufficiently low enough to prevent the pump from shutting off. One thing for sure: moving the switch up top will get rid of a cycling problem. Make sure you don't introduce a won't-turn-off problem.

I am suspecting you may not have a 43 PSI drop because your 100 ft rise may be an over-estimate. I hope so.

There are multi-stage jet pumps that can develop more pressure out of a shallow well than a single stage jet pump can. See page 4 of http://www.lockewell.com/pdf/goulds/HSJ.pdf

Remember that if you have 43.3 PSI drop for a 100 ft altitude climb, 80 PSI turns into 36.7 PSI. 65 PSI turns into 21.7.

 

[LLigetfa]

There are multi-stage jet pumps that can develop more pressure out of a shallow well than a single stage jet pump can.

I stand corrected. I was thinking of the multi-stage impeller (not jet) that are essentially the same as a submersible except the intake is a threaded inlet.

 

[Valveman]

Either a high pressure jet or a multi-stage centrifugal booster pump will work. BUT you must have a large enough pump to be able to work at 80 to 100 PSI if you want to get some decent pressure to the top of the hill.

 

[Tedr]

Thanks for even more great information and suggestions. I think I am beginning to understand how these systems work. I appreciate the patience of everyone in helping me (and others) learn.

I'll probably adjust the cut in/cut out to 20/40 before moving the switch because I doubt the pump can deliver much more than that at the cottage. If it can supply 20/40 I will be quite satisfied. A submersible may be in my future, but I'm trying to optimize the equipment I have as that's the least expensive alternative.

 

[Reach4]

I would start with a new 20/40 switch, but be prepared to adjust.

To raise or lower the cut-in and cut-out settings while keeping the
differential between those two settings constant, adjust the range
nut. The range nut is the 3/8-inch nut that adjusts the larger of
the two springs in Models FSG, FYG, FRG, and Type G Pumptrol
switches.
Turn the range nut clockwise to increase the cut-in pressure and
counter-clockwise to lower the cut-in pressure. Three and a half
revo
lutions of the range nut will change both the cut-in and
cut-out settings by approximately 10 psi.

Adjust the differential nut if you want to raise or lower the
cut-out setting while keeping the cut-in pressure constant. The
differential nut is the 3/8-inch nut that adjusts the smaller of
the two springs in Models FSG, FYG, FRG, and Type G switches. Turn
the differential nut clockwise to increase the cut-out pressure and
counter-clockwise to lower the cut-out pressure. Adjusting the
differential nut will change only the cut-out setting while the
cut-in setting remains unchanged.
​

 

[Tedr]

Thanks. Yes, I get that. The switch is a new one I installed recently. It was preset for 20/40 and I adjusted it to 30/50 to try to get more pressure at the cottage. I'll adjust it back to 20/40 before moving it up the hill to the cottage. Hopefully the pump can deliver enough pressure to achieve cut off at 40 psi at the cottage. If not, I may be able to lower the cut off below 40 psi until the pump can make it to cut off. I'm not sure how much adjustment there is in a typical switch. Anything better than the current 10 to 28 psi at the cottage would be a bonus.

If that doesn't work I will probably switch to a submersible.

 

[Valveman]

The difference in pressure readings between the upper and lower lever will tell you exactly how high it is in elevation. Then you would know what the pump will have to do to get 20/40 or 40/60 to the top.

 

[Tedr]

Life has been getting in the way of my plumbing education. I made a quick trip to the cottage to close it for the season, but before draining the water system I moved the switch from the pump to the pressure tank up at the cottage. Unfortunately I couldn't get the pump to start even though there was no pressure at the tank. It was probably a wiring problem, but I didn't have enough time to solve it. Although we have had a warmer than usual Autumn, freezing temperatures will arrive before I get another visit to the cottage so I had to drain the system and I didn't have time to sort out the wiring problem.

By the way. to install the switch at the pressure tank I had to release the pressure at the tank to zero. At the same time the pressure at the pump (from the water in the line below the pressure tank) was 20 psi. I assume that means the vertical lift is about 46 feet if the gauge is accurate.

 

[Valveman]

By the way. to install the switch at the pressure tank I had to release the pressure at the tank to zero. At the same time the pressure at the pump (from the water in the line below the pressure tank) was 20 psi. I assume that means the vertical lift is about 46 feet if the gauge is accurate.

You are correct.