Anyone have recent experience with VFD well pumps?

[STx]

The time has come to replace my well pump, the cheapy we installed only lasted 18 months and I really want to do it right this time and not have to do it again. We grow a market garden and have about 10 acres in addition to the garden that we'd like to keep somewhat green just to keep dust down. We've also got animals to keep watered and will one day be putting in a pond that we'll need to use the well to keep topped up since we only get about 24" a year of rainfall. And of course, there's the typical household use, which basically means that we have varying demands from 2GPM for most household use to 20GPM at 30PSI to run the drip in the garden to as much water as I can get for running big Ag impacts in the other 10 acres, so in theory, we're a prefect candidate for a large VFD pump.

I'm considering a couple of options now, the first is a 5HP Flint and Walling motor paired with a 10 stage, 55GPM pump, a Cycle Stop Valve and pressure tank. Option 2 is a Yaskawa VFD motor with the same pump and pressure tank but, no CSV. Price difference is about $800 but, in the grand scheme of things it's not enough to be a determining factor.

My concern really is that I've hard very mixed reviews about the longevity of the VFD systems but, I also can't really find any discussions about them newer than about 2015 which makes me wonder if maybe those reliability issues have been worked out now. I really don't want to have to deal with this well pump again for 15+ years so I want to choose the option that's going to give me the best longevity.

So, if you've installed a VFD in the last 4 or 5 years, what has your experience been? Would you do it again? What do you know about them now that you wish you'd known when you put it in?

I welcome any knowledgeable input you guys may have.

 

[CobyRupert]

Is this a submersible pump?

I don't know much about VFD well pumps, but have some experience with VFD's in general.
Make sure the pump motor is VFD rated. That is:

The first winding turn on a motor running on a VFD is subject to high voltages that can lead to insulation breakdown, and leakage currents that cause pitting to motor bearings. Make sure the pump motor is specially VFD rated.

VFD's usually hate long motor conductor lengths. How deep is the well (if a submersible)? Make sure VFD can drive pump motor at this distance. You may want to use special cable between VFD and pump so that your plumbing system doesn't become an antennae for the VFD's carrier frequency.

With above ground motors, running them at slower speeds on a VFD reduces the cooling action of their fans, and the motor has to be rated as being able to cool itself even when the turn down ration is 4:1 or 10:1 etc.... If a submersible, I'm not sure what the impact on "cooling" itself would be. But ask about the rated turn down ratio of motor.

Personally, I wouldn't mess around with unproven technology if you only want to deal with it once every 15 years. Stay with tried and true.
:2cents:

 

[STx]

It is submersible, the pump will be 140' down.

The motor and control box will be a "kit", same manufacturer and designed to work together.

I should also mention that our power is pretty pricey, we're averaging about $0.13 per kwh.

 

[3Ts]

When we put in our well, I was given the choice of VFD or a regular pump. The price at that time made the VFD a non-starter, so I can't help with VFD. However, it sounds like you actually have 2 separate needs. One for the house that is low volume, and irrigation which is high volume. To run a big pump capable of 20 GPM or so to provide 2 GPM for the house doesn't sound economical. How big is your well? Can you put 2 pumps in it? One for the house & the other for irrigation? If not, is a second well an option?

 

[STx]

It's a 5" casing, no way we're getting 2 pumps down that hole.

A new well is not fiscally possible, if it was I'd drill a BIG one that would give me 100+GPM.

 

[RNeumann]

I have a VDF pump and have had it about 5 years. It’s a great idea and the controller provides several of the “add on” features of a standard pump setup. I will definitely do it again. The VFD changes the electrical to 3 phase so you can use a 3 phase variable speed pump. The extra cost is the extra wire and the controller. The pump itself is about the same as a normal split phase pump.

In our area the two pump manufacturers that they use are Grundfos and Goulds. I’ve never seen anything else. Everyone here that I’ve talked to gets 20+ years from a well pump.

 

[Xfaxman]

No VFD experience, but have 8.5 years with a CSV. All good, no negative.

For your use a CSV uses less electricity than the same pump with a large pressure tank.

 

[EddieWalker]

Following to learn more about this.

 

[STx]

I've decided to go with the traditional pump and CSV, the VFD option ended up being about $1700 more and I just don't have the budget for it right now. I'm going to upsize my pressure tanks in a few months also to minimize the cycling as much as possible. Now I just need to fish the failed pump out of the hole, the first piece of down pipe broke when we tried to pull it. It's only about 30' down to the top of the pipe so it shouldn't be too difficult to pull it out, I hope.

 

[Xfaxman]

I've decided to go with the traditional pump and CSV, the VFD option ended up being about $1700 more and I just don't have the budget for it right now. I'm going to upsize my pressure tanks in a few months also to minimize the cycling as much as possible. Now I just need to fish the failed pump out of the hole, the first piece of down pipe broke when we tried to pull it. It's only about 30' down to the top of the pipe so it shouldn't be too difficult to pull it out, I hope.

Good luck with the recovery :thumbsup:.

Don't understand why you would put in a bigger pressure tank? The Cycle Stop Valve will minimize cycling.

This is what I am using, a 4.5 gallon bladder tank: Products – Cycle Stop Valves, Inc

.

 

[STx]

The cycle stop has a 5 GPM bypass, household use below that will still cycle.

I'm not using one of the plastic, fixed pressure cycle stop valves, they have huge head pressure when you get over 30GPM. I'm going to put in the CSV3B2T - CSV3B2T CYCLE STOP VALVE – Cycle Stop Valves, Inc

 

[Xfaxman]

Wasn't aware of that one, since we don't have a high flow rate. Ours only cycles below 1 GPM.

I have never seen ours cycle since we replaced the original Inwell pressure tank with the leaking bladder.

I have a light that comes on when the pump is running and an easy to see pressure gauge in the house that I monitor.

 

[aczlan]

I've decided to go with the traditional pump and CSV, the VFD option ended up being about $1700 more and I just don't have the budget for it right now. I'm going to upsize my pressure tanks in a few months also to minimize the cycling as much as possible. Now I just need to fish the failed pump out of the hole, the first piece of down pipe broke when we tried to pull it. It's only about 30' down to the top of the pipe so it shouldn't be too difficult to pull it out, I hope.

When you put your new pump in, make sure you put a good rope down the hole with it. That way you can still pull the pump out even if the pipe breaks. I would also use the heavy black poly pipe to run down the well, that way you have no joints between the top and the bottom.

Aaron Z

 

[STx]

I actually had a galvanized cable to run down with the last one, I can't tell you why I decided not to use it, I just did.

The black poly isn't available locally, everyone here uses Sch80 PVC. Yo special order it and have it shipped is cost prohibitive.

I have what I need to fish the ok'd one out, just haven't gotten to it yet.

 

[downslope]

It's a 5" casing, no way we're getting 2 pumps down that hole.

A new well is not fiscally possible, if it was I'd drill a BIG one that would give me 100+GPM.

Can you really only get 55 gpm out of a 5 inch casing? I would think you could do a little better than that but maybe the depth or screen size is limiting. What is the size of the down pipe to the pump? How many feet of static water do you have in the well?
Some of my neighbors are running VFDs in tree nurseries and they like them, but I know at least one was struck by lightning.

 

[STx]

I can't afford the jump to a 7.5 HP or larger motor. I'm actually not sure there are motors bigger than 5 HP that will fit.

Static level is 100', well is 150', pump will hang at 140' on 2" Sch 80 PVC.

 

[Lnk]

Just some information to help. I have no experience with VFD well pumps. However, I have many years experience with VFD at gasoline dispensing stations. Most gas stations have 2hp VFD motors in the tanks. These provide 10gpm at up to 12 fueling points, of course that is with an 8-12 ft lift and a 2" feed line. The reliability of the drives is very high, not sure the same reliability can be had in a residential well. That being said, gas station have drives and motors that are 10+ years old, and cycle on and off way more than any residential well. Motor cooling is not a problem in either application as both liquids remove heat. Gas station motors are rigidly mounted on a flange attached to at least a 2" schedule 40 black iron pipe as opposed to a well dangling off of poly pipe. Might actually make things worse. Not sure. Good luck with whatever you decide.

LNK

 

[Tractor Seabee]

Hanging the pump on plastic pipe is not a good idea. The vibration will gradually cause it to crack. Fishing it from the bottom of the well is not as easy as 30'. Hang it on a stainless steel cable. The price solved your decision making. I am always inclined to keep it simple so that would steer me away from the VFD even if price was not the object. There are well pumps that go 20+ years. More things to go wrong especially vital systems.

Ron

 

[Tractor Seabee]

Second thoughts; the best way to stop short cycling is to add a closed system storage tank rather than a larger bladder tank. Also on the VFD, I doubt they save any power cost to worry over. Their primary function is variable control of processes.

Ron

 

[cat fever]

I have the VFD pump. We just built the house so can't talk about how long it will last. I love the constant pressure. Our last house had the on/off type pump and I hated the pressure change especially while in the shower. It was more money but at this point I'm glad I did it.