Well Drilled - Results

[LittleBill21]

man i thought i understood my well, i have learned a ton so far,

valveman and goose, if you don't mind can you either provide a link or a dumb down answer as to why back pressure is easier on the pump then a high flow rate on a lower pressure?

 

[the old grind]

To better understand the pressure/power confusion consider your vacuum cleaner with hose connected to 'blow'. When you plug the hose (deadheading it) the motor revs higher due to the reduced o'all load while maintaining output pressure. Open it again and you can hear rpm drop when moving more 'fluid'.

We also must remember that as water seeks it own level a deeper casing just allows more to enter, and at pressure for depth as draw down lowers that in the casing. Draw down will influence how deep pump should be, but pump 'sees' mostly head to tank and only needs to remain submerged during peak usage/draw down. Setting it unnecessarily lower won't increase output or pressure, and means moving a larger 'column' (volume/mass) going to tank. Example: FIL's 270' well, static level at ~30', 1 1/2 hp pump at 80', hydrant above wellhead ('before' tank) and with two 'chick-chick' sprinklers shooting 30'+ arcs you'd never know they were running when filling the washing machine. (time to fill nearly the same)

Goose and valveman, you well guys are way ahead of us non-pros (plumbing contractors here, btw) and we're all getting a much-appreciated lesson. I agree that while VFDs can have many benefits, use on small residential well pumps are tough to justify. On our shop machines they can do much for low hp motors with heavy starting loads and particular rpm needs, but otherwise are just a way to expand markets/applications for such bling. Saving energy with them makes sense as hp goes way up, but is surely pie in the sky at < a dozen hp. (IMO, whole-house tankless water heater efficency/convenience are also over-promoted for similar reasons, ie sales) Worth the $$ and complication? NOT.

It's easy to over-think such an installation, but easy to goof up too. I'd say anyone going from shallow well or jet pump to a submersible will be so tickled with the increased volume pressure they'll think they did everything right. If they fell short of goal (GPM/draw down) resetting a pump deeper shouldn't too big a chore.

btw, My shallow well pump/tank and WH stay well ahead of my eco showerheads, but using a hose outdoors is a joke. Looking forward to it's demise and going submersible as a step between that and 2" gas pump with 1 1/2" fire hose to water lawn etc.

 

[Valveman]

man i thought i understood my well, i have learned a ton so far,

valveman and goose, if you don't mind can you either provide a link or a dumb down answer as to why back pressure is easier on the pump then a high flow rate on a lower pressure?

It is hard to explain because it is counter intuitive. 30 years ago I also thought it was hard on a pump to throttle it back with a valve. I had to learn differently myself. Actual pump curves are the best way to see that as the discharge rate of a pump is reduced, the amps or horsepower reduce as well. You would think it would go the other way, but it doesn't. But don't feel alone. I have to explain this at least 10 times a day, and many times it is to "pump engineers", as many of them do not understand it either.

I will see if I can post a picture of a pump curve, so you can see what I am talking about. Here is a curve of a pump that uses 15HP to pump 300 GPM, but drops to 6HP at about 5 GPM and the RPM of the pump stays the same, it is simply being restricted with a valve.

 

[Valveman]

There is some information trickling out that some of the newer pumps are not lasting as well when throttled back by either a CSV or a dole valve due to the way the impellers are designed (floating stack vs other designs). Cary (valveman, owner of CSV) can give you more information. I primarily use Goulds pumps but I usually do not use either CSV's or VFD's but I would not hesitate to use a CSV and actually have one on one of my personal wells with a 20 gallon bladder tank. Works as advertised. I'm not a big believer in constant pressure as I personally cannot tell you when the pressure swings from the cut on a 40 to the cut out at 60 but some people can I guess.

My own personal belief is that VFD's are a computer and the main reason I am against them is I do not think they can hold up to the Texas heat (95-100 deg F air temp and up to 120 deg + if in sunlight). Your cellphone will overheat in a hot car but somehow a VFD is supposed to last?

I worked in a large industrial facility with VFD's on several hundred horsepower motors for fan speed and we had to add an A/C to the VFD room and still had problems.

Pentair, which makes the same pump under many different names like Sta-Rite, Myers, and Flo-Tec, have had "floating stage" pumps for many years. We have been using CSV's with these for decades and have never had a problem. Goulds does not have "floating stage" type pumps and they work well with CSV't the same as Grundfos and many other brands.

The pumps in question are made by Franklin. They have recently changed their design from the old Jacuzzi, which they bought out to go in to the pump business. They are now making a "floating stage" type impeller. These impellers actually drag the diffuser below each impeller. As with the Pentair pumps, these dragging impellers are suppose to be made of Delrin type plastic, that is self lubricating. But apparently the Franklin impellers are not as good as the Pentair.

We have never had any problems with the Pentair "floating stage" pumps. And we have yet to see any problems with the new Franklin design. However, Franklin is saying their pumps can no longer handle the restriction of a CSV or even just a Dole valve or ball valve. I am not sure the Franklin pumps would have a problem with the CSV, I think Franklin just has a problem with the CSV. Franklin just doesn't like the fact that the CSV makes pumps last longer, allows the use of smaller pressure tanks, and does away with the need for VFD's, which is their most profitable item. They may have even designed their new pumps so they will not work with CSV's on purpose. If they did these pumps are also not going to work with Dole Valves or even just running at low flow rates. But I would not put it past them to design a pump that would not work with a CSV, just to be able to maintain their planned obsolescence. Either way, until we know more about it, I am suggesting the use of any other brand pump besides Franklin. Franklin has made many changes over the years to further shorten the life span of their pumps, and I am sure this last change is no different.

 

[the old grind]

Pulled a pump last year and ground the SS case open to see what 'went South'. Plates/impellers were of a hard clear plastic that looked/felt like polystyrene or acetate. Couldn't tell if either were 'floating' as they were cracked and crumbled too much to tell and pieces just sloshed around. No guess what might have caused the damage, and no grit or foreign matter found anywhere in the system.

We have been alerted recently that we are at the edge of a large area (MI's Thumb and below) where arsenic (IIRC) is common in ground water. Dissolved lime is a given in MI, but more of a prob on fixtures/surfaces that in pumps, tanks, valves or other bits we service.

Are diffused chemicals/gases a whole 'nother can of worms to deal with when choosing a pump?

 

[Egon]

man i thought i understood my well, i have learned a ton so far,

valveman and goose, if you don't mind can you either provide a link or a dumb down answer as to why back pressure is easier on the pump then a high flow rate on a lower pressure?

It is all about how much work the pump is doing. Increasing the amount of flow means more work has been done.

Increasing outlet pressure to reduce flow does not apply to positive displacement pumps.

 

[Valveman]

Pulled a pump last year and ground the SS case open to see what 'went South'. Plates/impellers were of a hard clear plastic that looked/felt like polystyrene or acetate. Couldn't tell if either were 'floating' as they were cracked and crumbled too much to tell and pieces just sloshed around. No guess what might have caused the damage, and no grit or foreign matter found anywhere in the system.

We have been alerted recently that we are at the edge of a large area (MI's Thumb and below) where arsenic (IIRC) is common in ground water. Dissolved lime is a given in MI, but more of a prob on fixtures/surfaces that in pumps, tanks, valves or other bits we service.

Are diffused chemicals/gases a whole 'nother can of worms to deal with when choosing a pump?

We have arsenic in our water as well, but I have never seen it cause problems to a pump. Those plastic and Stainless Steel pumps should not have problems with chemicals. Impellers coming apart like that are usually from an upthrust problem or maybe pumping some air, which will mess up the top of the impellers. Lack of flow usually takes out the bottom side of the impellers.

 

[bigdeano]

Pump cycling and changes in pressure can cause problems like changes in shower temperature. I put in a pressure regulator after the pressure tank to supply a constant 40 psi as the tank varies between 40 and 60. Be sure to use a regulator which allows water to go back to the tank if the pressure gets too high, as from thermal expansion.

 

[Valveman]

Pump cycling and changes in pressure can cause problems like changes in shower temperature. I put in a pressure regulator after the pressure tank to supply a constant 40 psi as the tank varies between 40 and 60. Be sure to use a regulator which allows water to go back to the tank if the pressure gets too high, as from thermal expansion.

That is sort of how a CSV works. However, with a pressure regulator after the pressure tank you are only getting a constant 40 PSI to the shower, while the pump is still continually cycling on and off between 40 and 60.

A CSV installed prior to the pressure tank keeps a constant 50 or 55 PSI to the shower, while at the same time it is keeping the pump running steady and eliminates the cycling.

 

[hawkeye08]

I would like to learn more about the CSV installation and if it makes sense for my situation. I don't want to hijack this thread, where can I find some good information to get me started? Thanks.