Well pump control for house and irrigation

[Mannekino]

I have a deep well with a 5hp pump feeding both our main house as well as multiple irrigation lines. The well pump is controlled via an 86 gallon pressure tank and during some irrigation days in the summer, this setup can kick on the well pump up to 100 times in a day, which we want to change.

So, we’re looking at placing an 1,800 gallon underground cistern up on the hill behind the house. The well pump would then feed the cistern with some float control switches and a 3/4hp cistern pump would feed the house and the irrigation lines via the same pressure tank.

Now, my wife is not fond of the potential of a mild plastic taste of our otherwise super-clean well water. We are lucky to have exceptional water quality. So, I am curious whether anybody can give insight into the potential of a cost-effective control setup where the well pump can feed the pressure tank in the main house separate from the cistern. The latter would then only be plumbing to feed the irrigation lines via a 3/4hp cistern pump and a constant pressure controller.

Thanks much.

 

[Reach4]

One way to stop the cycling is to increase the irrigation flow substantially.

A cycle stop valve is another way.

 

[Sponsor]

 

[Mannekino]

One item I forgot to mention in the first post is that a second reason that we chose the cistern option is for potential power outages in the winter and fire protection in the summer.

I am aware of the CSV solution for constant pressure, but that doesn't address the potential taste aspect that may arise in the winter when we do not irrigate, yet our drinking water would be sitting in the cistern for some time.

Thanks.

 

[Valveman]

With an 86 gallon size tank that actually holds about 25 gallons of water, I am guessing you have a 25 GPM pump? If that is the case the cistern and booster pump set up may be best for you. However, there is nothing better than good clean well water coming directly from the well. Anytime you put this clean water in a big cistern with air venting in and out, the possibility of contamination is an issue. Sunlight, temperature, and contaminated air through the vent can all have a negative impact on the quality of water in the cistern. Many people even have to regularly add chlorine to the cistern to keep the green stuff from growing.

A cistern full of water is not going to help during a power outage or fire unless you have way to get some of that water out. Elevating the cistern will only give you 1 PSI pressure for every 2.31 feet you have the cistern elevated. So normally you would still need a pump in the cistern to get water out, which without power will not be able to do so. A generator is the best way to be sure to have water during a power outage or fire.

Then when you have a generator, it can also run the well pump, which means you really don't need the cistern and booster pump if you can run the well pump with a generator.

If it is a 25 GPM, 5HP well pump or if it is a 35-40 GPM well pump, adding a CSV to the discharge of the well pump can stop all the cycling and eliminate the need for a cistern and boost pump.

But if it is a 25 GPM, 5HP with a really high water level, there maybe too much pressure for a CSV to work with, so a cistern set up like the following may still be what you need.

 

[Mannekino]

Thanks Cary.

I like to the set up you show for our irrigation lines -- a cistern with a booster pump, etc. Now, the question is whether I can design a water flow for the main house separate from this cistern, but still using the same well pump. Do I need a diverter valve to create a branch to the pressure tank?

 

[Valveman]

You don't need anything extra. After the CSV/pressure tank on the booster pump you can tee off the line as many times as you want. One tee to the irrigation and another tee to the house. The pump system doesn't know if it is feeding grass or people. It is all the same to a pump.

 

[Mannekino]

Yes, I understand, but what if I do not want water from the cistern feeding the main house? That's the main question I have. Thanks.

 

[Reach4]

So, I am curious whether anybody can give insight into the potential of a cost-effective control setup where the well pump can feed the pressure tank in the main house separate from the cistern.

You could feed the cistern via a new tee, a check valve, and a solenoid valve controlled by a float switch. The water from the well would go through new tee to the pressure tank.

 

[Mannekino]

Yes, I started to draw something similar. See below.

Now, I am not familiar with all the controls options, so any input would be appreciated. The pump control box I have is a Franklin 5hp control box with the following wiring. Particularly, I need to figure out a proper float switch control that controls a solenoid valve as well as the well pump via the pump control box. This control will need to get its input from the float switch(es), which will be placed in the cistern about 100 ft away up on the hill. That said, I imagine that the controls also need handle the possibility that there is water demand from both the pressure switch (for the main house) as well as the float switch (for the irrigation) at the same time. In this case, the main house should take priority. Perhaps, also a safety release (or control override) needs to be added? in case the float switch control demands water, but the valve remains closed (accidentally) and the pressure tank is already at 60 psi and does not want more water...

Lastly, any of you can advise on the right booster pump with the CSV setup? Goulds type? I have decided that this booster pump will be in my mechanical room so it will be protected, with the cistern up on the hill 25 ft higher and 100 ft way.

Thanks for the help.

 

[Reach4]

Never put a filter between the pump and the pressure switch.

It is much better to not have a check valve on the water coming into the pressure tank. There will be a check valve in the well at the pump.

A submersible in the cistern horizontally will use about 1/2 the horsepower compared to a jet pump for the same job. It is also is not subject to drama like priming. Do use a flow inducer.

What is the lower float switch doing? Typically people use a single tether switch and control the deadband by lengthening the tether.

 

[Valveman]

If you want to be able to run from the well pump to the house when the booster pump quits try this. A Cycle Sensor eliminates the need for the lower float switch as a safety.