Well Pressure Regulator

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Old 08-15-11, 10:25 AM
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Well Pressure Regulator

I have a 540' deep 6" well with a submersible pump at 320' used for irrigation. The well supplies 6 gpm and the 1 1/2 hp Goulds pump will deliver approx. 10 gpm. The irrigation system uses 6-8 gpm depending on which zone is on. Static water is 18' below ground level and I have a large pressure tank 4' tall and 2'-3' diameter about 80-100 gallon. I used a 1 1/4" line from the check valve on top of the pump to the pressure tank. When the pump starts their is little back pressure as the tank fills and the total head is around 20' which causes the pumo to overheat and fail. Is there a pressure valve that can be put inline to maintain a constant back pressure or would a valve to reduce the effective pipe diameter work?
 
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Old 08-15-11, 03:52 PM
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It is probably not the lack of back pressure so much as the pump cycling on and off that causes overheating. You need a "constant pressure valve".
 
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Old 08-15-11, 09:59 PM
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not sure why you would need a constant pressure valve when the tank size is more than adequate for the pump. i didnt read anything about excessive cycling. even at 10gpm.. an 80gal tank keeps the pump running at least 2 minutes before cutoff.

i suspect there is something else going on with the pump. backpressure or no backpressure... as long as its moving water, a submersible should stay running without a hitch until cutout pressure is reached.
 
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Old 08-16-11, 05:34 AM
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The "back pressure" on the pump would be the system water pressure and the height of the water level in the casing.........What is the pressure?
To trouble shoot a submersible pump you need a volt meter and clamp on ammeter to find out what is going on electrically.

The run capacitor is a potential problem based on the symptoms you describe.
 
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Old 08-16-11, 07:42 AM
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Lack of backpressure from a high static water level causes up-thrust. This usually melts the top couple of impellers, and does not overheat the motor. Overheated motors are usually caused by cycling or lack of flow. Motor and pump manufacturers have taught us that 2 minutes of run time is satisfactory, when all that does is barely make it last past the warranty period. Two minutes on and two minutes off still cause 360 cycles per day. Even 3 minute cycles cause 240 cycles when irrigating all day. Thatís lots of cycling and is usually what causes a motor to overheat, even with an 80 gallon tank that holds 25 gallons of water.

With a high static level in the well, a 10 GPM pump is trying to put out about 14 GPM. So if up-thrust or lack of back pressure is causing the problem, am 8 GPM Dole valve will keep the pump in itís curve, and even help with the cycling a little bit.
 
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Old 08-17-11, 02:59 PM
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Or . . . no tank. For irrigation, no tank is required. Add or reduce sprinkler heads as needed for coverage. When the pump is on, the water is on and when it is off, the water is off.

Valves can be opened and closed for different zones either manually or using a controller. Only thing to watch out for is not to cut off the output water completely. That will cause the pump's seals to blow out as it attempts to push against closed valves.
 
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Old 08-18-11, 06:37 AM
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With no tank and no back pressure that pump will really upthrust on start up with a static of 18'.
 
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