Question about C S V's

I have read quite a bit about csv's & from what I understand , basically the csv restricts water flow / volume . This restriction causes higher pressure between the csv & the pump & due to lower volume the water pressure between the csv & the pressure switch remains to low to cut off the switch when a tap is open . If this is correct , why couldn't the same effect be achived with a much less expensive , properly adjusted , manual valve such as a ball valve ? Am I totally off base ? I realize in a lot of applications where a manual valve is subject to being fooled with by people who doesn't realize the purpose of the valve & the importance of the valve being adjusted correctly that a tamper proof valve would be much preferred .

If you were always standing there watching a pressure gauge, and adjusting the manual valve to maintain a constant pressure, the principle would be the same as a CSV. You could restrict the flow with a manual valve anytime the pressure increases, and open the manual valve anytime the pressure decreases. Then when there is no water being used, you could adjust the manual valve to 1 GPM to slowly fill the pressure tank.

I use this as an explanation of how the CSV works frequently. It is like having a little man adjusting a ball valve to match the flow being used. When you use less water, the little man closes the valve a bit. When you use more water, the little man opens the valve a bit. When you are not using any water, the little man closes the ball valve to 1 GPM to allow the pressure tank to slowly fill.

However, the CSV works on pressure, and opens and closes automatically to match the amount of flow you are using. It would keep the little man very busy trying to continually adjust the valve. Now if you only use one particular flow rate all the time, you could leave the ball valve adjusted to say 7 GPM, and as long as you are using exactly 7 GPM, the pressure would remain constant. The problem with a manual valve, is that it can't make changes to flow automatically when you change how much water you are using. Otherwise, the principle is exactly the same.

Thanks for the reply . Why is it really important that the pressure tank fills at only 1 gpm ? My pressure tank fills at a much faster rate than 1 gpm . If a person had a well , pump , & pressure tank that was used only for lawn irrigation & the number of sprinklers stayed the same wouldn't the flow for this system stay the same & there wouldn't be any need to constantly adjust the valve or have a valve that adjusted itself ? One thing I didn't take into consideration is the amount of pressure change the pump produces as the water level in the well changes . Maybe I just answered my own question but I'll let you tell me whether I did or not .

Yes you can design a pump system to exactly match the irrigation system. You have to get it just right. That is the best way to do it if you never run a sprinkler on a garden hose or anything else.

The problem is getting it "just right". Even if you can make every sprinkler zone exactly the same, and design it to make each zone exactly the same as the size as the pump, things can still change. Your sprinkler nozzles will wear a little each year and let the sprinklers put out more water than they should. Your pump will wear a little each year which makes it produce less water. This will cause low pressure and your sprinkler pattern will get smaller and not reach the corners anymore.

If the water level in the well drops any over time, this will also cause low pressure. Many states require that the irrigation be sized to about 80% capacity of the pump to allow for these problems. However, that is one of the things that causes cycling. If you ever use a garden hose to run a sprinkler in a garden, fill a swimming pool, or the wife just lets it run to water flower beds, the pump will cycle multiple times per hour.

Even a shower in the house will cause the pump to cycle on and off 3 or 4 times per shower. Not only can these cycles add up over the years but, causes the pressure in the shower to go from maximum to minimum pressure several times during a shower.

The Cycle Stop Valve will allow you to run 80% of capacity without the pump cycling. It will allow you to match the sprinklers to the yard and not the pump. As many times you may need to run a large zone in the back yard, a smaller zone in the side yard, and maybe a really small zone by the driveway. This can be a water saving technique compared to needlessly overlapping zones to keep the pump from cycling. The CSV will give you constant pressure in the shower, which most people find enjoyable over the pressure fluctuations seen with a pump that is cycling on and off.

Because the CSV eliminates cycling and fills the tank at only 1 GPM, you can use a much smaller pressure tank. This saves money on the tank itself, saves square footage in construction, and reduces the area that must be heated. The CSV will usually even reduce the electric bill over a pump that cycles often. However, if a lot of very small zones are used for long periods of time, the CSV can increase the electric bill a couple of dollars a month. Some people get hung up on this, and don't realize that it is more than offset by the lower cost of the smaller tank, the smaller square footage and heating bill, and most importantly, by making the entire pump system last about 3 times longer than a system that cycles often.

If you get it just right, you can design a system without a CSV but, the CSV has many advantages. Mostly it allows you to be able to use water anyway you want. You no longer have to worry that someone left a hose running in the flower bed, or that the kids have been playing with the slip and slid for hours.