Cycle Sensor application

[dave4333]

We have a well which produces 4.5 gpm and a pump which pulls 5 gpm so a net deficit of 0.5 gpm. We have an irrigation system too. I am trying to prevent pump from running dry. The well has a reserve of about 600 gallons (450 feet deep with 40 foot static level).

I have a Square D pressure switch with low pressure cut off. The switch is 40/60 so it cuts off below 30 psi. We also have a 90 gallon Wellmate tank. We have had no issues until the other morning when we had no water. Pressure switch had cut off. I’m not sure if it was truly a low pressure situation or a glitch with the switch. It happened in the middle of the night.

Would the Cycle sensor be a good solution for our situation? Also, what would be the benefit of a cycle stop valve?
Thanks

[Cary Austin]

If you have a 10 GPM pump and it is cycling on and off while using 4.5 GPM, then yes a CSV would help.  A 90 gallon tank holds about 20 gallons of water, and your 10 GPM pump is probably running about 2 minutes to fill that tank.  That would take 4 minutes to fill while using 4.5 GPM.  But while you are using 4.5 GPM the pump is still producing 10 GPM and filling the pressure tank.  So your pump is basically pumping 10 GPM for 4 minutes, then it is off for 4 minutes while the tank supplies the sprinklers.  It is easy to pump a 4.5 GPM well dry when filling a pressure tank at 10 GPM for 4 minutes at a time.

A CSV would turn your 10 GPM pump into a 4.5 GPM pump.  The pump would draw a steady 4.5 GPM from the well while you are and because you are using 4.5 GPM.  There is no extra water produced to fill the tank and or pump the well dry.  There are many benefits to drawing a steady 4.5 GPM from the well compared to 10 GPM for 4 minutes then nothing for 4 minutes.  The big tank is also just seen as another 20 gallon demand that must be filled after the sprinklers are off and before the pump will shut off.  That extra 20 gallons to fill the big tank could be when you are pumping the well dry.

The low pressure cut off switch does not always protect a pump from running dry.  The 40/60 switch needs the pressure to drop to 30 before it can shut the pump off when the well is dry.  But if the sprinklers have been turned off and you are filling a pressure tank when the well pumps dry, the pressure will not drop to 30. the pump will not be shut off, the pump/motor will just get hot and be destroyed.

A Cycle Sensor is much better protection for a dry well condition as it doesn't look at pressure.  It looks at amps and knows when the pump is running dry.
See this.
https://vimeo.com/248374357

[dave4333]

I’m sorry. Our pump only pumps 5 gpm not 10. How would all of that affect our situation and application? Thanks

[Cary Austin]

Even a 5 GPM series pump will produce about 9 GPM at low pressure.  5 GPM is just the sweet spot in the pump curve.  It will do more than that.  So just change my figures to 9 instead of 10 GPM.  You can tell by how long it takes to put 20 gallons in that 90 gallon tank?

[dave4333]

Interesting. I actually timed it, and it took about 2 minutes, 40 seconds. I will definitely purchase the cycle sensor. I still don't quite understand the cycle stop valve. With a 40/60 pump setting and tank set at 38 psi precharge, what would be the correct valve to use? Pump is 1 hp. would it be a 50 psi valve?

[Cary Austin]

The CSV12550-3 would work with a jet pump.  The CSV12550-1 would be needed for the submersible.  But the CSV1A would be best and would work with either pump. 

Here is a link to a video which should help you see how the CSV works.

https://vimeo.com/248374194

[Cary Austin]

Interesting. I actually timed it, and it took about 2 minutes, 40 seconds. I will definitely purchase the cycle sensor. I still don't quite understand the cycle stop valve. With a 40/60 pump setting and tank set at 38 psi precharge, what would be the correct valve to use? Pump is 1 hp. would it be a 50 psi valve?

Measure how much water you get out of the tank before the pump starts and you will know how many GPM's the pump is putting out.

[dave4333]

I will check this weekend as it’s a weekend place. First time ever with a well. Just had it fractured. Went from 1.5 gpm to 4.5 gpm. Want to protect pump. When a given sprinkler zone runs, pressure drops to 40 and pump comes on. Pump runs continuously with pressure in system hanging around 45 psi. Once zone shuts off, pressure rises to 60 and pump stops. It sounds like for this application, CSV would give a constant pressure of 58 psi unless pump couldn’t keep up? I will definitely order the Cycle Sensor. I’m just trying to figure out which CSV I might need.

[Cary Austin]

Sounds like your pump is producing more than 9 GPM?  You will need the CSV1A for this system.

[dave4333]

I'm wondering if you could help me interpret some results. Our well is about 500 feet deep. Pump is set at 450 feet.. Before fracturing, water level was 90 feet. We just had a well test done. We get 4 gpm at 380-440 feet and 0.5 gpm at 220 to 280 feet. With the well test, Yield was 4.5 gpm, Time to recover is 2:28. Recovery is 40 feet. and static level is 22 feet. I'm not quite sure what all of the above means.

I was thinking about the CSV 125. This would be in an unfinished basement. If it gets waterlogged, how much water would weep out at any given time? Are we talking about just a little spot on the floor or a drip? And, if my pressure switch is 40/60 and tank is 38 PSI precharge, would I get 60 psi valve and just increase cutout of switch to 62 or so, leaving precharge at 38?

[Cary Austin]

Yeah doesn't make a lot of sense to me either.  If the well is only making 4.5 GPM from 440', it doesn't make sense that it will recover to 22' static in 2.28 minutes?  Recovering from 440' to 22' in 2.28 minutes would be a recovery rate of 252 gallons per minute?

Yes the CSV125 would work, but you would be better off with the CSV1A for such a small pump and in a basement.

[dave4333]

I believe it recovers in 2 hours 28 minutes. Not sure what that would make for gpm. Approximately 400 feet at 1.47 gal per feet, divided by 148 minutes = 4gpm?

[Cary Austin]

OK that makes sense.

[dave4333]

I guess I'm just trying to figure out the benefit of the CSV. In my situation, it would keep water pressure constant. If we were using anything like a shower or sink, the water would come out as normal and once pump came on, it would bypass tank and pump would run continuously. However, where pump might not be able to keep up (sprinkler zone + shower), we would notice a drop in pressure?

[Cary Austin]

Ok now we are back to how many gallons per minute does your pump produce?  Whatever size pump it is, it will produce more when the water level in the well is high, and less as the water level pulls all the way down the way it does on a 4.5 GPM well.  It really doesn't matter if it is 9 GPM, 14 GPM, or 17 GPM.  The pump is still putting out more than 4.5 GPM, which is all the well will make.  To irrigate and not draw the well dry you need to use 4.0 GPM or less.  When using 4 GPM while the pump is producing 9, 14, or more GPM, the pump will be cycling on and off while the pressure tank is filled and drained.  This is bad for the pump and the well itself.  You are basically surging the well up and down by drawing 9 GPM, then nothing, over and over, while cycling your pump to death at the same time.  That is what the CSV can solve for you.

However, now we need to know what size pump you have and how much pressure it can build when the water level starts out at 22' deep?  Sometimes a pump that will still work from 400'-500' will build more pressure than a CSV or your pipe can handle.  We can double up on the CSV's and stair step the pressure down as needed.  Then we just need to make sure the pipe can handle that pressure.  And usually it can for the pump to be set so deep to start with.