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Cycle Stop Valves General Info
What are Constant Pressure Valves?
Choking the Flow from a Pump Makes it Work Easier
What Pump and Tank Companies Don't Want You to Know
Cycle Stop Valves Save Money by Making Pumps Last Longer
Examples of Cycle Stop Valves on Residential Systems
Sizing a Tank for Residential Systems with Leaks
Planned Obsolescence: Pumps are Built to Fail
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What are Constant Pressure Valves?
A Constant Pressure Valve or CPV is a pump control valve that makes a variable flow pump out of any standard, constant speed pump. Attached to the discharge of the pump, a Constant Pressure Valve, automatically chokes back the output of a pump to match the users requirement for water. As the gallons per minute used decreases, the amount of electricity used by a centrifugal impeller naturally decreases without changing the speed of the pump.
The CPV maintains a constant pressure for the water user regardless of the amount of water being used. The CPV is completely mechanical requiring no electronics. Large pumps are now capable of very small flow rates without variable speed controls, huge pressure tanks, or water towers. Pumps equipped with a Constant Pressure Valve can operate safely from as low as 1 GPM to as much as the pump will produce.
The CPV can stop pump cycling, eliminate water hammer, extend pump life, and save electricity. The CPV can hold a steady level in elevated tanks and water towers or can deliver water to a city of 40,000 people from a tank as small as 44 gallons.
The Constant Pressure Valve or CPV is new technology that replaces variable speed pumps, water towers, and large hydro tanks. Recent advances in variable speed pumps have made them smaller and less expensive. Problems such as noise, vibration, voltage spikes, wire lengths, low flow cycling, and pressure spikes have not been solved since variable speed pumps were introduced decades ago. Problems with water towers and large hydro tanks have always been well known. Constant Pressure Valves eliminate these problems, are just as energy efficient, and give excellent variable flow performance without the problems associated with changing the speed of the pump.
There are many types of Constant Pressure Valves. The only non closing type CPV is a Cycle Stop Valve which can be maintenance and problem free. Cycle Stop Valves do not have screens, bypass holes or tubes, needle valves, and other controls that will cause problems in real world applications. Simple mechanical valves are a reliable way to get variable flow pump performance from any standard constant speed pump.
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Choking the Flow from a Pump Makes it Work Easier
Centrifugal pumps are counter intuitive. As pressure on a pump increases, the power required decreases. In other words, if you put a valve on the discharge of a pump and begin to restrict the output flow, the power required by the motor will decrease. Most people already have it in their head that choking a pump back will make the pump work harder and use more power. This is incorrect as the pumps work is easier, and the motor uses less power as the flow from the pump is restricted.
Most engineers falsely believe that the RPM of a pump must be reduced for the power required to also be reduced. This is simply not true when you are talking about pumps with centrifugal impellers. With these type pumps the excess back pressure (created by choking a pump with a valve) is a free by product of horse power. As the pump pressure increases, the weight of the water being lifted is reduced and the power required decreases. With centrifugal impellers, restricting the flow rate with a valve, reduces the power required proportionally. When pumping fairly cool water, these type pumps can be choked back to very small flow rates without any harm to the pump or motor. It is easy to tell if an engineer or pump installer truly understands what they are talking about if he or she understands this counter intuitive property of centrifugal pumps.
When all you are pumping is cool water at a constant pressure, it is hard to beat the counter intuitive or “magical” horse power characteristic of a centrifugal pump at a fixed speed. A variable speed controller would only be adding expense and technical complications, while trying to trick it into doing something that the pump already does naturally, simply, and inexpensively. This inherent property of a centrifugal impeller may seem almost “magical” but, is simply one of the only laws of nature that is truly Counter Intuitive.
There are many good uses for variable speed drive units but, pumping cool, clean water at a constant pressure is not one of them. Pumping other substances such as hot water or hydrocarbons may cause damage to the pump if flow is restricted too much. Pumping some materials such as blood may be sensitive to impeller RPM. Other products such as concrete or peanut butter may be sensitive to pressure. Moving these substances with centrifugal pumps or when using any positive displacement pump, a variable speed controller could be beneficial. When all you are pumping is fairly cool, fairly clean water the counter intuitive property of a centrifugal pump with the simplicity of a Cycle Stop Valve for control cannot be beaten.
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What Pump and Tank Companies Don't Want You to Know
Until the early 1970's, submersible pumps and motors that were being sold for homeowners were designed to last. Before that time it was usual for pumps and motors to last 20 to 30 years because they were designed strong enough to handle the abuse of cycling on and off. Since the 70's, companies have continually shortened the length of motors and replaced lifetime ball bearings with short-lived bushings. Pumps have been changed from having heavy duty brass impellers to all plastic. These changes were not made for the better but, rather to shorten the expected life of pumps and motors. This "planned obsolescence" is how pumps and motors are now designed, instead of building in the quality needed for a longer service life.
The average life of most pumps and motors that are being built today is about seven years. This means that some will last 14 years and others only last two years. For the average home owner it is usually the number of times the pump cycles on and off that determines how long the pump and motor will last. Normally the larger the pressure tank and the less water being used will cause less cycling on and off and lengthen the years of service from pumps and motors. The smaller the pressure tank and the more water used, the shorter the life of pumps and motors.
A Cycle Stop Valve or CSV is a simple device that drastically reduces the number of times a pump is cycled on and off. The Cycle Stop Valve can be used with very small pressure tanks and still double or triple the life of any pump or motor. The CSV controls the amount of water being pumped to exactly match the amount of water being used. This means the CSV can be used with very small pressure tanks because there is no extra water being pumped to cause the tank to fill. Pumping more water than is being used is what causes the pump to cycle on and off repeatedly. Cycling on and off repeatedly causes the pump, motor, controls, and bladder pressure tank to wear out prematurely.
The Cycle Stop Valve does this by supplying water for the home owner at a constant pressure. Pressure in the house remains steady while a single shower is running. When additional water is needed for a second shower, washing machine, pressure washer, irrigation sprinkler, etc., the Cycle Stop Valve opens more to supply the extra water needed. The person in the shower will never see a change in pressure or be scalded by hot water when additional water is used elsewhere in the home.
Many other devices such as variable speed pumps are being sold to try and accomplish this same constant pressure control. However, these variable speed controls are being manufactured by the same companies who have built in the seven year planned obsolescence into their pumps and motors. Variable speed controls are complicated, expensive, computerized, electronic devices that are also designed for short life expectancies. These devices last no longer and are no more repairable than any laptop computer which is basically their electronic cousin. Many of these variable speed controllers spin pumps and motors at many times the standard RPM. Although variable speed controls reduce the number of starts and stops, the increased RPM also reduces the life span of a pump or motor and keeps everything in line with their planned obsolescence of about seven years. Variable speed controls are promoted as an energy saving device. In reality variable speed pumps do not save anymore energy than a Cycle Stop Valve on a standard pump. Variable speed pumps can certainly never save enough energy to pay for their own added expense.
The Cycle Stop Valve is a simple and inexpensive way to supply water at a constant pressure to your home. Designed to reduce cycling and increase the life of pump systems, the Cycle Stop Valve is also a good way to beat big corporations at their own game. By making standard, cheaply designed pumps last three times their planned obsolescence, and by using much smaller than normal pressure tanks, a Cycle Stop Valve can be a great asset to your home water system. Since their beginning in 1993, hundreds of thousands of Cycle Stop Valves have been installed without causing a single pump or motor failure. Everyone deserves constant pressure. You and your pump deserve a Cycle Stop Valve.
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Cycle Stop Valves Save Money by Making Pumps Last Longer
Millions of rural homes across the country have there own well and pump system. Even in areas where water quality is not so good there are countless new ways to filter or treat water making it suitable for human consumption. Many homes in the city have a booster pump system as well. These pump systems boost low city water pressure to the needs of the home owner. Standard pressure tank operated home water systems average many on and off cycles per day. The pump fills the tank and shuts off. The water is used from the tank and the pump again comes on, fills the tank, and shuts off. This “cycling” is repeated dozens of times a day 365 days a year, which could be tens of thousands of cycles per year. Day by day these cycles add up and is usually the cause of a pump system failure. Those systems with the most cycles will last the shortest length of time. "Cycling" causes the premature destruction of the pump, motor, tank, switches and any other component in the system.
The amount of time a pump system will last can be calculated in number of cycles. Why would pump manufacturers make a pump that would last 500,000 cycles when they can make more profit by building pumps that only last 200,000 cycles? This de-engineering or “planned obsolescence” has led to most pumps and tanks having become a “throw away” item. These throw away pumps and tanks are not repairable, have very little that can be recycled, and usually end up as another burden in our landfills and the pocket book of the home owner.
On the pretense of trying to engineer efficiency into our equipment many manufacturers are purposely engineering out dependability or longevity. Using a constant pressure valve to mechanically restrict the output of a pump to exactly match the usage can save as much energy as varying the pump speed with expensive and problematic electronics. Therefore, the longer your pump system last, the greater your savings in "Life Cycle Cost." A constant pressure valve will eliminate 90% of the cycles which can make a pump system last three to four times the normal life expectancy. When a pump system last several times longer than expected, savings to the home owner is easy to figure.
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Examples of Cycle Stop Valves on Residential Systems
Older type water systems used a pressure tank and a pressure switch for pump control. The pressure tank would fill at the full rate of the pump until the pressure reached a high or cut out point and the pump was shut off. The draw down or amount of storage in the tank could then be used at whatever rate was required in the house. When the tank was empty the pressure would be at the low or cut in pressure and the pump would be started. This process was repeated over and over at a rate determined by the size of the pump and the amount of draw down in the tank. Even small pumps with large tanks could cycle on and off excessively when using any flow less than the full flow rate of the pump. This cycling causes water hammer and can prematurely destroy the equipment in a water system.
The one inch Cycle Stop Valve is made for pumps up to 30 GPM and has a 1 GPM minimum. This will keep the pump running, maintaining a constant pressure, as long as at least 1 GPM is being used in the system. A Cycle Stop Valve set at 50 PSI will maintain 50 PSI when the house is using from 1 GPM to the maximum the pump will produce up to 30 GPM. When there is no water being used the 1 GPM minimum going through the Cycle Stop Valve will then enter the pressure tank until the pressure reaches 60 PSI and the switch shuts off the pump. The draw down or stored water in the tank can then be used as needed in the house. Ice makers can fill, toilets can be flushed, and tooth brushes can be washed before the pressure lowers to 40 PSI and the pump is started. Once the pump has started the Cycle Stop Valve will keep the pump running until there is no more water being used.
The following are different ways of using Cycle Stop Valves on residential systems. Check the Cycle Stop Valve operating specifications making sure that the valve you choose can handle the pump you have.
Example 1
An example would be a 3 HP 25 GPM pump set at 200 ‘ with a static level of 100'. The largest zone in the sprinkler system is 20 GPM and requires 50 PSI. We have decided on a tank that holds 10 gallons of draw down and will be installed with a Cycle Stop Valve. Shut off head of this pump is 460'.
Subtracting the static water level (100') from the shut off of the pump (460') we get 360' or 156 PSI as the back pressure on the Cycle Stop Valve. The CSV1 can only handle 150 PSI and should not be installed indoors. The CSV1Z can handle up to 400 PSI and has no problem being installed indoors. Make sure that all plumbing between the Cycle Stop Valve and the pump can handle the maximum of 156 PSI. The CSV1Z has a minimum of 25 PSI friction loss and 12 PSI of reduced pressure fall off at 20 GPM. This means that we should add the 25 PSI or 58' of head to the TDH required from the pump. Maximum pumping level is 180', added to the 58' and the 50 PSI or 115' of pressure required gives us a total head of 353'. This pump can deliver 22 GPM at 353' of head which is more than enough to run our largest zone.
Because of the 12 PSI fall off pressure, we must set the pressure on the Cycle Stop Valve 12 PSI higher than the 50 PSI required. Adjust the Cycle Stop Valve to hold 62 PSI while running about 2 GPM from a hose bib. Then turn off all water outlets and wait three minutes while the tank fills at 1 GPM. After waiting three minutes for the tank to fill the pressure has reached 68 PSI and the pressure switch is backed off until the pump is shut off. After opening a hose bib in the system the pressure tank drains until the pressure drops to 48 PSI and the pressure switch starts the pump. The Cycle Stop Valve will now hold 62 PSI if 2 GPM is being used and 50 PSI if 20 GPM is being used. Only when flow needed is less than 1 GPM will the Cycle Stop Valve allow the tank to fill to 68 PSI and the pressure switch will shut off the pump.
Example 2
Another example might be a 1 HP 15 GPM set at 100' and needing 40 PSI. A CSV150 is selected and is to be installed in the well. Using a weight bearing coupling or (CSC) the CSV150 is installed under the pitless adapter which is 6' underground. A 5 gallon draw down pressure tank installed in the house and is about 15' higher in elevation than the installed Cycle Stop Valve. With the CSV150 holding 50 PSI at it’s elevation, we will see 6.5 PSI less or (43.5 PSI) at the elevation of the tank. After closing off all water usage the pressure will rise to about 52 PSI at the tank in about three minutes. At this point the pressure switch should be backed off until the pump shuts off.
Cycle Stop Valves can be installed in many different locations on many different pump systems. Questions about your installation are welcome. (See Also "Sizing a Tank for Residential Systems with Leaks")
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Sizing a Tank for Residential Systems with Leaks
When using a Cycle Stop Valve, small pressure tank and a pressure switch for controlling a small pump system, consider the system leaks. Always the worst case scenario is a demand or leak on the system that releases less than the amount of the minimum flow of the Cycle Stop Valve. With a one inch Cycle Stop Valve the minimum flow is set at about 1 GPM. If we have ˝ of a GPM leaking in the system, the Cycle Stop Valve will always allow the pump to produce a minimum of 1 GPM. ˝ of this GPM will be going directly to the leak and the other ˝ of a GPM will fill the pressure tank until the pressure switch shuts off the pump. Then the ˝ GPM leak will slowly use all the water in the tank and the pressure will drop to the point where the pump will be restarted by the pressure switch.
Use a pressure tank that will keep the number of starts per day lower than the maximum allowed by the motor manufacturer. Using a motor with a maximum of 100 starts per day allowed we would figure the tank size as follows. 1440 minutes per day divided by 100 maximum starts allowed equals one start every 14.4 minutes.
Adjusting the Cycle Stop Valve and pressure switch to get a three minute run time during a zero flow condition means that the pump must remain off for the other 11.4 minutes to get a minimum of 14.4 minutes per start. Using the worst case of ˝ GPM leaking we would multiply 11.4 minutes times the ˝ GPM getting a drawdown required of 5.7 gallons.
Using a pressure tank with 5.7 gallons of drawdown and having a leak of ˝ GPM it will take 11.4 minutes to drain the tank from 60 PSI to 40 PSI causing the pressure switch to start the pump. It will take a 50 PSI Cycle Stop Valve a minimum of 3 minutes (if the leak stops for that period of time) and a maximum of 6 minutes (if the leak continues) to refill the tank from 40 PSI to 60 PSI so the pressure switch can shut off the pump. On for three minutes and off for 11.4 minutes gives us a minium cycle time of once every 14.4 minutes or 100 starts per day worst case. Double the size of the tank and it cuts the number of cycles per day in half. When using a Cycle Stop Valve the worst case number of cycles per day can be easily controlled by the amount of drawdown in a tank.
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Planned Obsolescence: Pumps are Built to Fail
There are pumps in a famous fountain in Chicago that have been running since 1927. Turbines at some of the older dams have not required maintenance in 60 years or more. There is a light bulb that has been burning in a fire station for over a 100 years. I have a 1947 Jeep that still runs as good as ever. This tells me that we can build things to last when we want too.
When we started Cycle Stop Valves in 1993 we thought the only thing they did was keep pumps from cycling off and on. Over the years we learned that Cycle Stop Valves save energy, make pump systems last longer, use much smaller pressure tanks, eliminate water hammer, and deliver constant pressure to the user. All of these things are good, but many manufacturers do not like it.
Companies that sell electricity will not say it out loud but, they do not want devices that save energy. Companies who make tanks do not want you to be able to replace ten tanks with a single tank and a simple valve. Makers of pipe, fittings, and fixtures don’t want water hammer eliminated. Some manufactures will spend millions buying out a competitor just to phase out a good product, so they can put even less quality into their own product. Some motor manufacturers would rather warranty a large percentage of their motors than make a motor that will last.
Even though pumps, motors, and tanks were designed to only last a short period of time, Cycle Stop Valves can double or triple the life expectancy of these pump systems by simply eliminating the cycling on and off that comes with everyday use. Everyone is being economically wounded by companies who practice “planned obsolescence”. “Planned obsolescence” is a cancer that feeds on our natural resources while destroying consumer confidence and contractor relations. Designing a product to prematurely fail while claiming to sell a quality product is fraud, just as any other kind of false representation.
Cycle Stop Valves make pumps and motors last longer and use smaller tanks, while saving as much energy as variable speed drives. Therefore, it is the policy of many companies who manufacturer pumps, motors, tanks, and variable speed drives to discredit Cycle Stop Valves any way they can.
Consumers only search for the cheapest price when they believe quality is no longer attainable. Cycle Stop Valves make cheaply built pump systems last longer than was planned by the pump and motor manufacturer. Cycle Stop Valves eliminate warranties and help stamp out planned obsolescence in pumping equipment.
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