I have a 4 inch well system with a well mate tank of about 40 gallons. My pressure switch is set at a low of 40 and a high of 60. I have pressure in the holding tank of 38 when the tank is empty. The only problem I see is the pump seems to cut off and on more than I would like to see it and only runs a very short time before it shuts off.
My real question for you experts is what would be the effect if I had a low pressure on the holding tank, say about 30 pounds, and what would be the effect if I had a high pressure on the holding tank, say at about 50 pounds?
Another question what would be the effect if an irrigation system consumed more gallons per minute in the 40 pound pressure range than the pump could put out? I can see that the pressure on the irrigation system would drop and therefore the outflow but would it reach a point to where the pump would ever cut off?
Others here are better experts at setting tank pressure. But here's a stab at some of it. Setting your low pressure lower will result in a period when you have a painfully low pressure to the house. If you can live with this, than okay. As for the high setting, will the switch accept a higher pressure? Can the pump work at the higher pressure without working too hard? And will you really get much more volume with the higher tank pressure? I have my doubts. Volume is what's important here. Maybe a larger tank, or a second tank is in order. But that depends on your usage habits, and how much you want to spend. There's also posts here about all kinds of neat gizmos, like Smart tanks and and regulators and such, that you ought to look into. But in my mind, there's just no substitution for more volume. a bigger tank will have the effect you want, less pump cycling. But you need to decide if: you have the money for it, do you need it. Meanwhile, you can play with pressure switch and tank precharge and see if there is enough inprovement.
Pump cycling often can be cause by a water log tank. The old tanks just had air above the water which would slowly be absorbed until almost gone. You could then just pump some more air in with a bicycle pump ete. Newer tanks have a bladder to prevent this. However, they will eventually degrade.
Air contracts and expands with pressure while water for all practical purposes doesn't. The contraction of the air allows more water to enter and the expansion allows more air toleave the tank with each cycle. If this air bubble is small, only a little water can enter the tank when the pump is on and therefore the pump will have to come on sooner once this little bit of water has left the tank
My holding tank is a bladder type 40 gal. tank. Just so that I can understand the system better I would appreciate if somebody would explain to me what the effects of over pressurizing and under pressurizing this tank would be.
I recently replaced my well-rite tank after just three years of operation because the bladder failed. Well Rite was very good about sending me a replacement under warranty no questions asked.
In the process, I learned alot about tanks so maybe I can help. First of all, here's the Well Rite web site - it has alot of good info.
I think your tank bladder may have failed. Here's the logic. The air space that's normally on the outside of the bladder represents the volume of water that can be removed from the tank between pump cycles. If the bladder fails, the tank becomes just like the old non-bladder tank. Eventually, over time, the air charge disperses into the water and you get less and less air volume and more and more water in the tank. The pressure of the air volume doesn't change - there's just less of it.
What this means is that there's less water volume to draw down between pump cycles - therefore the pump cycles more often.
Now to your other questions. If the bladder is OK, the wider apart you set the cut-in and cut-out pressures, the more air volume you have and thus the more draw-down volume you get between pump cycles. HOWEVER, this will also flex/stretch the bladder more and possibly reduce it's life, I'd guess.
A pre-charge pressure of 30 pounds just stretches the bladder less and reduces the air volume - the pump will still cut in when the pressure reaches 40 pounds and out when it reaches 60. I THINK that if you set the pre-charge pressuer at 50 pounds (or anywhere above 40), the tank will draw down but the pump will never cut on.
As to your irrigation question, assuming a properly functioning bladder tank set for 40 - 60 pounds. Your well pump has a maximum head pressure at a certain flow rate this is represented as a curve on a graph. If the flow rate of your irrigation system meets the graph at a pressure less than 60 punds, the pressure switch will never reach the cut-out pressure. Your irrigation system will be at the constant maximum pressure the pump can put out at that flow until you turn off the irrigation system - then the flow goes into the pressure tank until the tank reaches 60 pounds and cuts the pump off.
In my case, my pump can put out more than 60 pounds at the full flow of my outside faucets (irrigation) so the pump would cycle on and off for hours as I watered. The life of a pump is measured in cycles. Turn it on once and it will run forever, turn it on 10,000 times and it will fail - so I wanted to make it so the pump would not cycle while I was irrigating.
I put a pressure relief valve in the system that keeps the pressure at 50 PSI at anything above a trickle of flow. Now, whenever I have any faucet on (even the shower) the tank will draw down to 30 pounds and the pump will kick on and the pressure immediately goes up to 50 pounds and stays there until I shut off the water. Then the tank slowly fills up to 60 PSI and cuts off.
I've re-thought the tank-pressure-over-50 question and I was wrong earlier because the pressure switch senses the pressure in the line OUTSIDE the tank. A bladder pressurized to 50 pounds will either stretch to its limit or will become restricted by the outlet pipe of the tank. Either way, at some point it will no longer be providing it's pressure to the system outside the tank. At that point, the pressure would draw down to the 30 pount cut-in pressure and the pump would turn on. The cycle would continue as normal but the bladder would be severely stretched. - I think [img]/forums/images/icons/crazy.gif[/img]
Yes, it does look like a failed bladder. some of them are replaceable but IMO the work is not worth it. As for the tank pre-charge, proper setting is 2 psi below the cut-in pressure. This optimizes pump run time (drawdown). Changing it will not accomplish much of anything useful and if carried too far can cause excess wear on the pump.
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