Well Pump Expansion Tank

[Pettrix]

I got a new expansion tank for my well pump. Inside there is a plastic like cap and when I pushed on it, nothing happened. Is that supposed to come out or move? I don't want to install it and find out that I needed to remove the inside or something wasn't correct with it. It also looks like it's off center and not centered in the hole where the water line enters.

I took some pics to show what I am talking about.

 

[Alan46]

I got a new expansion tank for my well pump. Inside there is a plastic like cap and when I pushed on it, nothing happened. Is that supposed to come out or move? I don't want to install it and find out that I needed to remove the inside or something wasn't correct with it. It also looks like it's off center and not centered in the hole where the water line enters.

I took some pics to show what I am talking about.




View attachment 1970590

View attachment 1970591

My suggestion is call the company that made the tank and talk to a tech person! Let us know the outcome!

 

[Roadworthy]

You could go with Alan's suggestion. My pressure tanks are significantly larger than yours. At the top of mine is an air fill like you'd find on your car or tractor tires. The appropriate pressure before you add water is a nominal 30 psi. Actual preferred pressure depends on your system pressure, the tank instructions should clarify. The lower opening is the water input. Mine is a 1 1/4 pipe thread to mate with my supply.

 

[mrmikey]

Actual preferred pressure depends on your system pressure, the tank instructions should clarify

I think the usual setting is 2-3 PSi below low pressure cut on.
The op's picture is an odd one, least to me. I've never seen a pressure tank without a schrader valve to charge it. That second pic, is it looking down actually inside the tank?

 

[WinterDeere]

Yes, as Roadworthy said, there should be a Schrader valve there. And as mrmikey already noted, it should be charged to 2-3 psi below your well pump pressure switch cut-in pressure, when the system is de-energized.

I'm not sure what you have going on there, but a condom of some type over the Schrader valve is normal, to keep it clean, as these things go many years between re-checking in most applications.

 

[Pettrix]

That second pic, is it looking down actually inside the tank?

Yes, the 2nd pic is looking inside the tank from the bottom, where the water line connects to.

These smaller tanks are for constant pressure VFD well pumps. They don't require large tanks.

 

[ericm979]

The tank's minimal docs say they're pre set at 40 psi from the factory. I think I'd leave it alone.

 

[mrmikey]

That piece that you refer to is a reinforced piece at the bottom of the bladder or it's where the bladder was formed...possibly both. I presume it's there so that you don't wear a hole in the bladder and lose your air charge should the 1" nipple protrude into the tank too far or if someone starts poking things into the tank.

 

[WinterDeere]

The tank's minimal docs say they're pre set at 40 psi from the factory. I think I'd leave it alone.

That's a normal way to deliver them, but doesn't imply they shouldn't be adjusted. 40 - 60 PSI is a very common well pressure switch setting, and it's easier for a plumber to relieve a few PSI during installation, after checking with a gauge, than to haul a compressor or pump down to the basement to charge the thing. And if you're one still running 30 - 50 PSI, also easy enough to let 12 psi out thru the valve.

This doesn't apply to the OP, if he's running a constant-pressure rig, but for everyone else, this is important:

Having your tank bladder over-charged can result in both short cycling AND massive pressure losses before cut-in. Round numbers for demonstration, let's say you have a 40 - 60 PSI well pump switch and a tank bladder pre-charged to 50 PSI. Turn on the system, and the well will charge everything up to 60 PSI cut-out, before turning off. Then you use some water, and get nice linear pressure down to 50 PSI, at which point pressure in your plumbing almost immediately plummets toward zero, as the bladder is completely expanded and there's no water left to push out of the expansion tank. If you're taking a shower, you'll notice great pressure, then a total loss of water, then it comes rushing back with a bang. Not good.

Having your tank bladder under-charged doesn't cause this problem, hence the recommendation to run 3 psi below cut-in. However, going too low also reduces useable tank volume, what they call the "draw-down" capacity, between pump re-starts. This is because there is less air space remaining in the tank, when the bladder is under-charged. So, even though there's water left in the tank, there's no bladder left to push that volume.

Setting the bladder right at cut-in would maximize the draw-down capacity, but run the risk of pressure loss right at cut-in. Hence the advice to pre-charge to 3 psi below cut-in.

For OP: I've never rigged a constant-pressure pump, they weren't a thing back when my family owned a plumbing business. But I would strongly suspect that one would want to set the bladder pressure (empty tank) right at your constant pressure setting, or just a few PSI below it, for the same reasons: maximizing draw-down while preventing pressure cycling.

 

[steve tym]

The plastic thing in the bottom is part of the tank, leave it be.
On a constant pressure system, the air charge should be 70% of the running pressure.

 

[Valveman]

Looks like a double cap on the Schrader valve. That other part should unscrew the same as a cap on the stem of a car tire. As was said, with most VFD constant pressure systems you want the air charge 30% less than the water pressure set point. It doesn't really matter how large the tank is when using a VFD. The slight drop in pressure needed to energize the pump means the pump will come on after using a cup or two of water no matter how large the tank is. That is just one of the many problems associated with a VFD constant pressure pump. The tank bladder probably went bad because of the VFD as well. The tank bladder doesn't move far but is continually moving a little as the VFD never really locks into a set constant pressure. Changing it out to a CSV constant pressure system will make your life easier and save a lot of money over continually replacing those expensive electronic VFD controllers. The Cycle Stop Valve is designed to make pump system last longer while delivering strong constant pressure. The VFD systems are designed to make money for the installer and pump manufacturer.

 

[MAX-24-Dean]

@Valveman
I agree with your post, I installed plenty of VFD's that later gave customers problems.
Not much money to be made in Cycle stop valve installations when compared to a VFD install.

 

[Valveman]

@Valveman
I agree with your post, I installed plenty of VFD's that later gave customers problems.
Not much money to be made in Cycle stop valve installations when compared to a VFD install.

I know right? And thanks! The CSV was invented to replace VFD's and big pressure tanks in 1993. We were using CSV's to solve the problems of VFD's back then, and CSV's are still solving the problems with VFD's today. The big pump manufacturers labeled the CSV a "disruptive" product in 1994. I had no idea what that was. I soon learned manufacturing a product that makes pumps last longer and use smaller tanks will get you shunned by the entire pump industry. Thirty something years later I am still fighting the same battle. Still trying to keep people from falling for the VFD hype.

I have become a real conspiracy theorist. If they will go to such extremes to hide the facts about pumps, what else are they lying about? "Planned obsolescence" is the number one design criteria in manufacturing, used to keep people purchasing the same products over and over again. For less than 10 bucks a Cycle Stop Valve could be manufactured into and just become a part of most pumps. You should have seen the look on the engineers face when I explained this. Making the Cycle Stop Valve come already installed as a part of every pump would basically put many pump manufacturers out of business. Pumps would no longer cycle themselves to death, which would reduce the number of pumps sold by maybe 90%. Large pressure tanks would no longer be needed, cutting production of tanks by probably 90% as well. Variable Frequency Drives or VFD's would only be needed on a tiny fraction of pump installs with unusual applications, taking billions of dollars out of the pump industry overall.

Adding a Cycle Stop Valve to every pump application would save pump owners billons of dollars, and that is not acceptable to the pump industry. Makes me wonder if they are also hiding the cure for cancer and many other things as well.

 

[Pettrix]

So far I've had the VFD going 10 years with zero issues. The bladder tank is also fine. I'm just installing another VFD on a different house that's why I bought it new tank for it

 

[jyoutz]

So far I've had the VFD going 10 years with zero issues. The bladder tank is also fine. I'm just installing another VFD on a different house that's why I bought it new tank for it

I just had our pump and controller replaced two weeks ago. The last VFD controller and pump was replaced on 2009/10 (can’t remember). It was a one phase power unit; the new one is three phase, so I’m hoping at least to see lower power usage. But my 2hp pump is at 660’ so it works pretty hard. We did install 4 check valves in the pipe at equal distances along the pipe, so it stays charged between demand.

 

[WinterDeere]

I just had our pump and controller replaced two weeks ago. The last VFD controller and pump was replaced on 2009/10 (can’t remember). It was a one phase power unit; the new one is three phase, so I’m hoping at least to see lower power usage. But my 2hp pump is at 660’ so it works pretty hard. We did install 4 check valves in the pipe at equal distances along the pipe, so it stays charged between demand.

You sure on those numbers? According to Oakville, a 2 hp pump is going to run down to about zero flow at just 600 ft. You're 10% deeper than that, and probably looking for nearly 10 gpm for most residential requirements. I'd guess 2 hp might be good down to 475 ft for that, but no deeper.

At 660 feet, I think you'd want at least 3 hp, if not more for a larger house or property with plumbed out buildings or any irrigation.

 

[jyoutz]

You sure on those numbers? According to Oakville, a 2 hp pump is going to run down to about zero flow at just 600 ft. You're 10% deeper than that, and probably looking for nearly 10 gpm for most residential requirements. I'd guess 2 hp might be good down to 475 ft for that, but no deeper.

At 660 feet, I think you'd want at least 3 hp, if not more for a larger house or property with plumbed out buildings or any irrigation.

I saw the old pump and the new pump, both 2hp. And the flow of the new pump is very good. Maybe the check valves are the answer? It’s a 3 phase Franklin submersible and it’s putting out 9-10 gpm at the house. The well is 680’ total and the pump is at the bottom of 33 20’ pipe sticks.

Edit: I do irrigate all summer and run lawn sprinklers, but one circuit at a time.

 

[steve tym]

A 5 gpm, 1 hp pump stops pumping at about 660', so a 2 hp should do just fine depending on the series. 3 phase motor will run better, but will not reduce power consumption, might even be a little worse because of the phase conversion from single to three phase.
Check valves should be installed every 200'. Sounds like your installer did a great job and used top of the line equipment.

 

[mrmikey]

We did install 4 check valves in the pipe at equal distances along the pipe, so it stays charged between demand.

Not sure but I thought I read somewhere that installing more than one check valve wasn't a good idea. Wish I could remember but it was something to do with one locking up the next one due to pressure being trapped against a closed valve...or something LOL.

 

[WinterDeere]

I saw the old pump and the new pump, both 2hp. And the flow of the new pump is very good. It’s a 3 phase Franklin submersible and it’s putting out 9-10 gpm at the house. The well is 680’ total and the pump is at the bottom of 33 20’ pipe sticks.

Maybe the Oakville table I referenced is not typical. It was just the first I found.

Maybe the check valves are the answer?

Check valves are probably a necessary evil at your depth, but they definitely don't help to compensate for pump capacity. You get a small pressure drop across each check valve, equivalent to the spring pressure divided by bore cross-section, probably just 0.5 PSI. Their function is to avoid system bleed-down, with larger vertical drops (higher pressure at pump).

A 5 gpm, 1 hp pump stops pumping at about 660', so a 2 hp should do just fine depending on the series.

Yep. But he has a 10 gpm pump. Remember, HP is just an ability to do work, that work being the product of both pressure and flow. For a given size motor, you can only achieve higher flow by transitioning to an impeller design that will cost you in pressure.

Choosing the right submersible pump for your water well.

Some water wells can be very deep at over 800’ or more while others are shallow at 50’ or even less. Water demands vary from just a few gallons per minute to hundreds of gallons per minute. In this overview we are going to explore the factors affecting the selection of the correct submersible well

oakvillepump.com

Not sure but I thought I read somewhere that installing more than one check valve wasn't a good idea. Wish I could remember but it was something to do with one locking up the next one due to pressure being trapped against a closed valve...or something LOL.

I ran into this problem in my last house. What happens is that all check valves have a small leak-down rate. But if one farther down has a higher leak-down rate than one up higher in the system, the result is it pulls a relative vacuum on the line. The pressure switch up top doesn't see this, since it's isolated from the line by a check valve up top. But when the pump kicks on, it's slamming fresh water up into this vacuum, and "bang!"

The system where I observed this had only one check valve up top, just upstream of the pressure switch, as the whole system was only 150 - 200 feet deep. It made a hell of a racket, every time the pump kicked on. I had a well specialist come take a look at it, as my knowledge is just general plumbing (we didn't have wells where I grew up), and it took him about 8 seconds to look at the system and tell me to remove that check valve up top... not necessary. After that, everything behaved well, but I wouldn't know what to do with a 600 ft. deep well.