View Full Version : Constant pressure well pump controller / Irrigation question

Todd Burch
01-08-2014, 2:14 AM
I'm getting ready to have a well dug on my property. 3.25 acres. Along with household use, I plan to drip irrigate a bunch of trees. Well will probably be 220 ft deep.

The first bid I got from my well guy, he suggested a 1.5HP motor and a 20GPM pump and a PC266 tank with 1.25 PVC SCH 80.

I then told him I wanted to irrigate trees and grass around the house. He then bid a 2HP 20GPM pump, PC366 tank with 1.25 SCH 80. The price went up a bit. Fast forward a few months.

I talked with him yesterday (the receptionist girl, actually) and asked her to confirm that the above was the proper motor / pump, and she recommended (after talking with someone in the background) a 2HP, 20GPM pump, PC66 tank (much smaller) and a sub drive 100 constant PSI controller, with 1.25 SCH 80 pipe. The price went up again.

Any well experts out there? I was just reading (on the franklin web site) about constant pressure controllers. Seems the controller merely controls the (sometimes existing, in a retrofit application) motor and makes it variable speed in order to keep the pressure constant. Do I understand it correctly?

Is this what I need? I guess my concern initially was volume of water, not really pressure. However, I understand I need pressure to get the water out of the sprinkler heads.

When I call an irrigation guy the day after I close on my house, will he be telling me "so sorry - not big enough"? Lot is roughly 250 wide and 580 feet deep. Well will be about 200 from the front, and the longest irrigation run might be 300'.

Thanks, Todd

Steve Rozmiarek
01-08-2014, 9:42 AM
Todd, sounds like massive overkill to me, but it would make a nice system. It'll give your sprinkler contractor a lot of options. My yard is similar in size, and I have roughly half the well capacity. When I installed the sprinkler system, I had to use 26 zones. Your system can do the same watering with a lot less. Adding zones is the work around for a smaller supply, and it is an effective one.

Lee Schierer
01-08-2014, 4:58 PM
You need to know the water delivery capacity of your well and the height of lift to determine which pump you need. The pump performance curve will tell you how much water it can deliver for the height it has to lift the water and then you can start determining the pressure loss in the piping.

Steve Peterson
01-09-2014, 12:58 PM
Do you have any hills on the property? A storage tank at the top of a hill will do the best job of providing constant pressure. Every 2.3 feet of elevation provides 1 PSI of pressure. 100 feet of elevation provides 43 PSI. The pump can run continuously when filling the tank instead of constantly cycling on and off to maintain pressure in a small tank.


Todd Burch
01-09-2014, 1:31 PM
No hill on the property, per se, but the property is on the side of a hill. Approx 34' difference in height between the front right corner (high) and the back left corner (low).

Lee - I believe my dad (just up the hill) was getting about 30 GPM when his well was dug. He's 40' higher than me. He drilled 260' deep.

Steve Jenkins (a member here) called me yesterday to explain his irrigation setup too - very helpful information.

I'm starting to feel the quote would be a good setup. Maybe overkill and expensive (just shy of $8800), but flexible.

Todd Burch
04-02-2014, 2:21 PM
I got my well in. Forward process. Phew! Water taste good. 236' deep well. Top of water is 73'. Pump is 160' deep.

Now, I just need electric!

Bryan Rocker
04-02-2014, 4:32 PM
Having been on a well for years the two things I would not skimp on would be the pressure tank size and the hp of the pump, its better to have to much than too little. My other recommendation is that you have a pressure control valve easily accessible so you can adjust the pressure do your liking, keep in mind that there will usually be a 20 psi different between high and low. For some reason they like to give you a 20/40 switch and a 30/50 switch. I personally adjusted my 30/50 up to a 60/40 switch so that you will get better pressure and flow everywhere. I would also go with the larger 366 tank since its actual volume is 119 gallons.....


Tom M King
04-03-2014, 8:46 PM
I put in a Grundfos constant pressure last fall. It was the third pump we've put in in 34 years. The constant pressure is a real luxury after living with a regular pressure switch for so long.

I hang the pump on a stainless cable. The cable is about 15 feet longer than the pump depth. Outside the top, it goes through a cable pulley that's mounted on a short piece of chain. I hook the chain in the chain hook on the top of my tractor loader bucket, and lift the pulley about 6 feet above the top of the well. The end of the cable has a loop that I shackle to the hitch on my pickup. Pickup pulls cable, which pulls pump up. No sweat, no strain, and I can change the pump without calling, or paying the well guy. Without the weight of the pump on the PVC pipe, it doesn't have a tendency to break, and a couple of helpers can easily handle it.

eugene thomas
04-03-2014, 9:41 PM
I went with VFD type system. Nice to have 70 psi steady. As to price coast me around 500 more than regular well control system but not beating pump up every time pump starts.

Bryan Rocker
04-04-2014, 11:28 AM
Well I just learned something new, never heard of a constant pressure well pump system...will have to look into this, my well pump is at least 15 years old.......