I'm going to get rid of my 40-year old basement jet pump and extend my well casing above ground and install a new submersible. My pump guy quoted me on a new pump using my existing pressure tank (fairly new) which will give me about 10 gpm at 70 psi. He also gave me an optional price to go with a constant pressure pump (VFD?) that he said is the top-of-the-line system. I know the standard systems have been around forever and work great, but I'm open to getting new technology that may save electrical costs . . . if it works. Any advice? Experiences? Warnings? It's a $900 additional cost, which I'm willing to spend if it's worth it.
From another thread. Search for Constant Pressure.
As I said the Grundfos SQE is the best of the VFD units available. This is because they do have a small pressure bandwidth to work with. Also because they have been around longer than the other brands and have had time to work out more of the bugs. However, they have made several changes to the SQE over the nine years they have been available. None of the other brands have been around long enough to know how they will last. Although the SQE has a small pressure bandwidth, when there is a small amount of water being used, such as a leak with a stream about the size of a match, the SQE will ramp up and down for a short while then fault out. A dripping faucet or running toilet seems to be the death nail for any of these VFD units.
Franklin switched to the switch instead of the transducer to increase reaction speed. The older Franklin units and any other VFD that uses a pressure transducer does not react fast enough. When the sprinkler system is turned on these units react so slow that the little bladder tank bottoms out and causes tremendous water hammer. When the sprinklers are turned off, the VFD reacts so slow that the pressure spikes and blows something up before the pump has had time to slow down.
It is good that these type units have troubleshooting built in, because it is one feature that is used often. A VFD is a computer. Let a computer control your pump system and you will go thirsty. When home computers blink out you are inconvenienced. When a VFD computer blinks, you are out of water.
The CSV gives the same performance and energy efficiency of a VFD with the simplicity and dependability of only one moving part instead of a computer. Many people have switched, and continue to switch to CSV from VFD everyday.