Switch vs VFD for submersible well pump

If you are intent on spending money, your funds would be better spent on a single speed submersible and install molded plastic round tank with a float switch, timer and a small jet pump to deliver water from the storage tank to the home appliances at a much lower pressure with greater flow and not worry about it??

The well pump feed pipe would pump water through the drain tapping of the molded tank and the piping from the tank to the home would come from the tanks drain tapping as well off the same tee. The limit switch would also be inserted through the lid of the tank.

It is better for a deep well submersible to let run flat out and spool down to a gradual stop anyway to reduce the amount of torque to almost none and put less stress. on your drop pipe and pump wire.

Deep well or multistage turbine pumps were designed for pumping light sweet crude oil in their original use and then for water well pumping. The use of a timer to control the submersible pump would let you fill a storage tank until it is full over a long period of time and then the float switch would control the operation of the submersible only when the float switch is low for a minute and shut off and then restart in an hour or two hours and simply run for one minute for each cycle.

Your new submersible pump will last longer and the storage tank will allow you to store more water that you would typically use and the jet pump that feeds water to the water appliances in the home can provide more water if needed at a lower pressure putting less stress on your homes piping.

single phase speed drives are made.

Whoa. Let me ask first what, exactly, is the objective of the exercise?

Or, to put it another way, what aspect of the usual pressure switch control system are you trying to improve on?

In terms of cost and reliability, it is really really hard to improve on a system with a deep well submersible paired with a correctly sized pressure tank and controlled by a pressure switch. The usual problem — sometimes leading to premature pump failure — is an incorrectly sized pressure tank (too small) and frequent pump cycles. Such a, system should be capable of reliable operation for upwards of 50 years, assuming that quality components were used in the first place.

Now the most common complaint I used to hear about such systems, usually from folks who were used to city water, was that the pressure varied at the outlets. Well, yeah. But I had a cure for that: run the pressure switch on the high side (usually 40/60) with a quality pressure reducing valve on the outlet set just below the on pressure of the well pump — typically 35 psig. And a small expansion tank beyond that to cope with the hot water heater, precharged to 35 psig. That gave pretty constant pressure barring piping loss, and enough pressure for even the most demanding fixtures, and was reasonably reliable and cheap.

The only times I have used the intermediate storage tank idea mentioned by @leonz were when I was dealing with a low-yield well. Then it works well, but at the expense of more complexity and expense.

I just heard about the VFD well pumps recently. I have a relative who is putting on a large addition along with a new well and is going with a VFD system. Its not in use yet.

I have heard they are pretty pricy.

There are You Tube videos on the subject.

From what I have read I would stay away from them but I am old and don't know any better.

I have heard that the well companies are going in this direction

It seems to me from reading the literature that a VFD well pump package might be a reasonable consideration — with considerations. The first is that it should at least be investigated as an option if one is replacing a failed submersible pump. It will, however, from what I have seen, be considerably more expensive than simply replacing the pump, and therefore if the rest of the system is operating well it may not be a good choice.

Another consideration is that it will do nothing to help with problems with the well itself — particularly wells which have too low a flow (for which it will be worse than before, assuming the rest of the system is sized and installed properly) or too low a capacity for the system demands (rare, but it does happen).

They do not eliminate the need for a well pressure tank, although a carefully designed system may be able to use a smaller size. This is because there is a definite minimum flow from the pump, and the pressure tank is required to prevent the pump from trying to run at a lower flow (which will destroy the pump) by allowing it to cycle on pressure, just as a conventional setup will cycle. This may not be a problem on smaller domestic pumps, but the tank still has to be there. The pressure tank is also needed to provide flow until the pump comes up to speed — which appears to be fairly quick on smaller pumps — but is a consideration (again, more so on larger pumps).

I have read a claim that the electronic controllers are more reliable than a conventional pressure switch. This I very much doubt, unless the pressure switch is in a very unfavourable situation.

The jury seems to be quite ambivalent on the impact of poor quality electric power and, by extension, the ability to run on standby power. A straight submersible and pressure switch arrangement will run on truly horrible power; about the only thing that will kill it is running the well dry, but I'm not so sure about the electronics used in the variable frequency drives.

I'm rather with @EBEBRATT-Ed up there — but then I don't care for cars with dozens of computers on them, either…

The nice thing about 2 pipe jet pumps is there is nothing electrical in the well ever and use the jet pump to fill a storage tank and use a small centrifugal with a bladder tank to deliver all the water you need from the tank as both of them can be protected by lightning arrestors.

A pump jack works well and always has.

I've got a little experience in this area. We currently have two of the Grundfos Constant Pressure systems, and two of the standard single speed submersibles (spread out over different places, but I pay for repairs on all). There are advantages and disadvantages to both. I have a constant pressure system here at my house/main farm. It was originally a single speed submersible, but the tank went bad and I upgraded the whole system. The VFD really does allow the pump to cycle less, which is good. I can't speak to energy use, but overall I've been satisfied. I've got the pressure set at 60 psi, which is awesome for cleaning up equipment and filling tanks - and the showers in the house are like going to a car wash. The pressure stays between 59-62psi no matter what the demand is (within reason). The main single speed submersible that we have is at a farmstead where we mix most of our spray loads. The pump was put in in the early 90s, and has never missed a beat. I'm sure it's on borrowed time, but I'm not messing with something that works. That particular pump replaced a jet pump that was put installed in the 60s, which replaced a pump jack put in when the REA came through in 1939.

Someone mentioned lightning. I suppose the CP system might be more susceptible, but my experience has been that when there's a lightning strike, we're going to need a new pump. And new TVs and appliances. The second single speed has been replaced twice in my memory - both times due to lightning. It has a surge protector, which may or may not have saved it a few times - hard to say.

The constant pressure system is very particular about the placement of the pressure sensor. Much like anything, it is important to have a professional that understands and is trained on the system install the thing. But honestly, since my kids are drinking this water, I'd say let's go ahead and use a professional for anything well related.

The tank on my house CP system (15 gpm) is a 1 gallon tank. It looks tiny but has performed beautifully. That being said, if I didn't have an automatic generator, I'd rethink the installation. The time between when the power goes out and when the water stops is pretty quick if you're in the shower somewhere between lather, rinse and repeat. 30 seconds waiting for the generator to kick in isn't too terrible.

Finally, we had a problem a few years back at the well where the other CP system is located. The pump was at 65 feet in a well that was 108 feet deep. During the summer, the static level fell below the pump. The CP system shut itself down (until the pump was lowered). My experience has been that a single speed in the same situation will run until it burns up.

Sorry for the long post.

Sounds like the CP systems are ok. Constant pressure is nice but with the cost I don't see any real advantage other than no needing a well tank of the usual size.