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Old 11-20-15, 02:12 PM   #1
stevehull
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Default lowering well pump pressure

I am in the process of designing a new home to replace the old drafty farmhouse we are currently living in as a stop gap measure. One of the issues is water pressure and its cost.

We use a geothermal heat pump in a pump and dump configuration. Water from well with 1.5 HP pump about 150 feet down. Produces about 15 - 18 gallons per minute. All I need for the GTHP is about 5-8 gpm max, pressure is not necessary.

From an energy perspective, moving water about is simple, just overcome the resistance of the pipe or conduit - providing pressure is expensive.

The current setting on the well relay is 40/60 psi and I am considering lowering it to 20/30. The only thing I "need" high pressure water for is a shower (25 psi water is really, really weak). But I can buy a pressure booster pump for ~ $100 and have that kick on just to shower valves (pump on shower light switch). Another run of PEX from the manifold is all it will take.

There are other advantages. The deep well pump lasts FAR longer and peak starting current is way less.

Anyone played around with this?


Steve

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Last edited by stevehull; 11-20-15 at 03:32 PM..
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Old 11-20-15, 07:39 PM   #2
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Buy an inline pressure regulator for your GTHP. I've seen them online and the local well guys can order them. If it is a continious flow, an orifice in the line could work too.
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Old 11-21-15, 03:30 PM   #3
stevehull
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Phil,

I may have not made my point clearly. I am trying to decrease my water pressure in my tank. This should save me a LOT of money and extend the pump life. Putting in an orifice only keeps the pressure up if I am understanding you.

I gotta believe that a lot of us on this forum are on water wells. A small investment in a booster pump (just to showers) allows a lower water pressure 99.9% of the time. I don't need high pressure to washing machine, dishwasher, sinks, etc - just shower.

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Old 11-21-15, 08:54 PM   #4
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How far down is the water? If the pump is lifting the water 150 feet, that's over 60 PSI at the pump just to get the water to the surface. In that case, the energy savings would be small.

If the pump is lifting the water a "short" distance (short relative to 150 feet), then pressure reduction will save money and wear on the pump.

A really nice system would have the main pump set to cycle, say 10 to 25 PSI, with a large pressure tank set for that pressure range to feed the heat pump and a booster pump. The booster pump with its own pressure tank set for the higher pressure would feed the entire house.
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Old 11-23-15, 08:04 PM   #5
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Steve, I think I see your point. My well is 180 ft deep and pumps another 75 feet higher after it leaves the surface. I had the 1 hp pump put in service about 1990. The PVC tubing string was changed because of hair line factures caused fron the pump torquing the tubing. It should have not been used in a well anyway.

At any rate, you must have a bladder type pressure tank. Again, I have got 25 years of service from one. If the pressure in the tank is decreased, the pump kicks on more often. There is a point where adjusting the tank pressure and the relay won't go any lower. I have had mine down to off at 30 psi and on at 20 psi. With a full stream of water, the pump is on 25% of the time.
If I put an auxillary pump on it, I'm thinking it might collapse the tank's bladder. Could be wrong there. The kWh usage would probably go up unless it's a super efficient pump.

I check the pressure tank pressure at least once per year and keep that up to specified pressure. IMHO, that's the major reason the tanks go bad. The bladder expands to a size that streatches the bladder and causes undue fatigue. The second reason for failure is undersized tanks. I buy the largest ones I can find. If the pump is constantly kicking on/off, it will wear the entire system out much faster. Also, the larger the tank, the less chances of freezing too.

I have been wondering if anyone has tried using nitrogen in these tanks? My truck tires love the stuff.

I hope this helps.
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Old 11-23-15, 08:49 PM   #6
stevehull
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Phil,

I have two bladder tanks - in parallel. The reason is that, years ago, the single bladder tank diaphragm broke and the pump started short cycling. But I didn't know it. Pump died. $$$$$$$

Now I have two 50 gallon bladder tanks with the correct air pressure set for the differential pump pressure relay. Just a couple years ago, I noticed that one tank had lost its diaphragm, but the pump was NOT short cycling as it was using the capacity of the other one. I just bought another new bladder pressure tank to replace the old one.

Pressure bladder tanks are FAR cheaper than deep well electric pumps.

If I do change the set point pressures to lower levels, I know that I must also change the air pressure in the bladder tanks.

With the larger capacity in the two bladder tanks, the pump runs longer, but with fewer off - on cycles. As I understand it, the number of cycles is what kills submersible pumps.



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