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chevdog
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Follow-up on well water pressure
09/04/03 12:28 PM
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Thanks for the info that you gave me about the questions I had about a drop in water pressure to our house - the what is it with me and wells? post. If you can help a bit more I would appreciate it.
I checked the pressure reading at the well and observed the following:
* Full (available) water pressure w/pump off was 65psi. Pressure gauge is located on the same pipe outlet that the pressure switch is on (between well and pump).
* I turned on hose bib at tank outlet until pump kicked on.
* Pressure cut-off was 35 psi.
* I adjusted cut-on to 40 psi, and cut-off to about 62 psi.
Here's what happens as water pressure drops - I can see the pressure switch diaphragm move slowly as the pressure drops until the contact finally trips. At that point, the pressure gauge reads about 40 psi so that seems OK.
However, right after the cut-on trips, the pressure drops to almost nothing - like 10 psi - then there is a second or two until the pressure comes right back up, finally cutting the pump off at about 60 psi. That's the lag that we are experiencing in the house - water dwindles to almost nothing. then quickly increases to regular pressure. It's annoying because it always makes me wonder if the water's coming back 
Why does the pressure drop so dramatically? I have not yet checked the tank charge pressure, but it seems that at the 40 psi cut-on there should only be a mild ripple in the supply rather than a big drop, then back up. Is the pump losing its prime (new 1.5hp pump) and then having to make up the head?
Nick
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egon
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Re: Follow-up on well water pressure
[re: chevdog]
09/04/03 01:53 PM
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Check your tank air/blader pressure.
Egon
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RobS
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Re: Follow-up on well water pressure
[re: chevdog]
09/04/03 02:08 PM
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Almost sounds like a check valve gone bad. Is there a check valve at the pump (question for the experts). What holds the pressure in the system when the pump kicks off? 
Rob
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chrisjbell
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Re: Follow-up on well water pressure
[re: chevdog]
09/04/03 02:33 PM
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My guess (I'm no expert, but have a well system that I maintain) is that you're getting flow back into the pump. That would leave me to believe that there may be a problem with the pump, but you might consider installing a one way valve - I do that in a few places with my gravity fed irrigation water.
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chevdog
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Re: Follow-up on well water pressure
[re: chrisjbell]
09/04/03 02:44 PM
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Thank you for the help.
I'll check the air pressure in the tank first to ensure that it's where it needs to be - about 2 psi below pressure switch cut-on psi.
As far as what holds pressure in the system, I assumed that it was the air pressure in the tank. There is no bleed down of pressure during times of no water usage - pressure remains at the upper range of the limit - about 55-60 psi. I have no idea if the pump itself has a check valve (submersible, about 280' down), but if it did not have something then wouldn't the water pressure bleed down during off-time (no water usage).
I like the one way check valve suggestion - would it simply install into the supply line that comes out of the well, between well outlet and pressure switch?
Thanks again.
Nick
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chrisjbell
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Re: Follow-up on well water pressure
[re: chevdog]
09/05/03 01:07 AM
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I like the one way check valve suggestion - would it simply install into the supply line that comes out of the well, between well outlet and pressure switch?
That's what I'd do. Like I said (or should have) I'm no expert, but it seems to make sense to me. I figure if your pump is already starting to flake out that you won't loose anything by trying this and that you're pressure tank, etc., won't notice a difference.
My well comes in through PVC pipe, and before it hits the pressure tank is filtered for sediment. I don't have a one way valve on my well, but if I were to try one I'd probably put it right after the sediment filter.
But do bear in mind that I'm an unlisenced, uneducated amature... Hopefully some more experienced folks will jump in.
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egon
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Re: Follow-up on well water pressure
[re: chrisjbell]
09/05/03 05:33 AM
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Forget my comment on checking the tank bladder pressure.I did not pay enough attention to your comments.
There should be a check valve at the pump. This appears to be holding as the tank maintains pressure when there is no water being used.
My quess is the well produces some gas. When the pump kicks on the check valve opens and the pump becomes temporary vapour locked till the gass passes thru. Tthis allows the pressure drop to almost zero. When the pump picks up water the pressure will again start to increase.
Egon
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chevdog
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Re: Follow-up on well water pressure
[re: egon]
09/05/03 06:50 AM
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I checked the tank pressure and it is right on 38 psi, which makes sense for the 40/60 pressure switch that's being used.
In order to check the air pressure in the tank, I turned off the power and ran the water until there was no water pressure. What I observed was that as I ran the water (no power - just pressure from the tank) the gauge reading slowly fell as you would expect it to. When the psi hit the cut-on level at the pressure switch instead of a continued slow drop in pressure, the pressure immediately fell to nothing and that was the end of the water out of the hose bib.
What puzzles me is that it's as though the well either has 40-60 psi of water pressure or nothing - there does not seem to be any pressure below 40 psi. But - I don't lose water pressure during times non-use. I was anticipating that as the water ran the pressure would continue to slowly drop to nothing, not fall from 40 to nothing, like off of a cliff. I just don't get it. I am tempted to replace the pressure switch since it's cheap, but I don't want to start just throwing parts at the problem.
I don't want to pester you with all this, but I would sure like to figure out what's going on before calling the well company. I'm not so sure that I'll call the ones that installed the pump, so I wanted to get some good knowledge before talking to anyone else.  Thanks!
Nick
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WVBill
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I drew this picture to help me understand.
Here's my theory: If you have two check valves in your system and the one down at the pump has failed, then most of the water between check valve #1 and checl valve #2 would drain back down through the pump creating a partial vacuum between the head of water and check valve #2. When the pressure switch cuts in, the pump pushes the head of water and the partial vacuum up and it's this partial vacuum (now compressed to your 10 PSI up through the system. As soon as the "slug" of air/vaccum passes the pressure guage, it reads the true pressure of the water.
Does the water you draw in the house seem to have small air bubbles in it?
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RobS
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Re: Follow-up on well water pressure
[re: WVBill]
09/05/03 07:31 AM
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Yeah, it sure sounds like a check valve problem of some sort. Imagine a spring type check valve at the pump. It holds as long as the pressure is enough to overcome the spring (a normally open valve in this case). As soon as the pressure drops to the spring load it opens and dumps everything out.
It was also mentioned that the pump is 280 feet down. That is a tremendous amount of pressure head to the pump. That may be a factor of some sort too
Rob
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egon
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Re: Follow-up on well water pressure
[re: chevdog]
09/05/03 09:08 AM
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Chevdog:
I've posted again as I did not properly read your original post.
Gas build up below the pump may be your problem which is not a problem the way your system is working.
Egon
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chevdog
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Re: Follow-up on well water pressure
[re: WVBill]
09/05/03 10:55 AM
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No, I do not see any small bubbles in the house water - I know what you are talking about though. We had them when the first pump was starting to run out of water - looked like a light froth when you ran the water.
I think that our system - if it has any type of check valve - would only have 1 valve (at pump), not 2, as there is nothing above ground that even remotely looks like a check valve. I'm going to go ahead and talk to a well company too - they may have some experience with this type of thing. Being older and hopefully slightly wiser this time I will find out up front what's going on. To their credit at least, I was never billed for any of the pump work that was done, but I also think that this situation should have been checked out. I think that they installed the pump, ran it to check the drawdown, then took off.
I also wanted to add that there is no problem with water volume, pressure, or quality other than that cut-in intitial burp.
Thanks for your help and patience 
Nick
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CJDave
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Re: Follow-up on well water pressure
[re: chevdog]
09/07/03 12:53 AM
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It sure sounds like the bladder tank is slightly over charged......if you have a bladder tank that is.
CJDave
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mikell
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Re: Follow-up on well water pressure
[re: CJDave]
09/07/03 06:36 AM
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I had a problem at mycabin with the checkvalve after the pump because the pressure switch was on the pump But you don't have that problem. A check valve before the pump cured my problem. "Dankoff solar" website tells how to set and what tank pressure to use.
mikell
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mikell
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Re: Follow-up on well water pressure
[re: mikell]
09/07/03 07:01 AM
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From Dankoff solar website
How to reduce water pressure
Pressure adjustments are made at the pressure switch. On a standard switch there are two adjustment nuts, with a spring under each one. Turning counterclockwise will lower the settings. You will see the result by watching the pressure gauge as the pump cycles on and off. FIRST, loosen the nut on the LONGER screw. This will reduce both cut-in and cut-out pressure. Set it for the CUT-IN that you desire. Second, adjust the nut on the SHORTER screw. It adjusts the CUT-OUT only. Cut-out pressure should be around 2/3 of the cut-in pressure.
Once the pressure is set and everyone is satisfied, reset the precharge air in the pressure tank. This will maximize its storage and minimize on/off cycling. To reset the precharge, first make note of the cut-in pressure. Now shut off the power to the pump. Release water until the pressure gauge drops to zero. Measure the pressure of the tank's air bladder using a tire pressure gauge at the fitting on top of the tank. Set the air pressure to 2 or 3 PSI less than the cut-in pressure. Restart the pump. Finally, write down the running time per cycle. Write it on the wall, so the performance can be checked later to detect pump wear or other problems.
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turnkey4099
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Re: Follow-up on well water pressure
[re: RobS]
09/07/03 03:48 PM
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Quote:
Yeah, it sure sounds like a check valve problem of some sort. Imagine a spring type check valve at the pump. It holds as long as the pressure is enough to overcome the spring (a normally open valve in this case). As soon as the pressure drops to the spring load it opens and dumps everything out.
-----------------------------------------------
Well, no. Check valves (in water systems) are designed to hold agains pressure from the discharge side. i.e., they only open when pressure rises above the system pressure. Usually they are a flapper or poppet type opening towards the discharge side.
quote
It was also mentioned that the pump is 280 feet down. That is a tremendous amount of pressure head to the pump. That may be a factor of some sort too
------------------------------------------------------------
The only head pressure would be the distance from the water level to the top of the well. Pressure of water inside the pipe is balanced by pressure outside the pipe. There is a question of inertia starting a long column of water moving tho.
All in all, in spite of years fooling around with wells and pumps, I have no clue at all why the pressure would drop to almost nothing as the pump starts. 
Harry K
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CJDave
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Re: Follow-up on well water pressure
[re: chevdog]
09/07/03 06:57 PM
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Dear Shev-Lay, One of the reasons that I hesitate to get involved in these discussions is that after spending years and years in the pump and water supply business I have learned that the general public operates on a set of almost-truths and it's difficult to break through that barrier to actually get them straightened out. What is going on with your setup is this: The hydro-pheumatic aspect of the system is entirely maintained by the bladder tank. As long as the bladder is slightly off the bottom of the tank, there is pneumatic. As soon as the bladder bottoms out, it's strictly hydro, and as you know, water doesn't compress, so the system pressure goes to zero. As soon as the system pressure goes to zero, the pressure switch......which is probably set somewhere in the thirties for "on" .....feels the pressure drop and starts the pump. THAT's IT....end of story. What has to happen is you will need to adjust such that the pump starts BEFORE the bladder hits bottom.....while the system still has some semblence of pneumatic left in it to maintain pressure. The bladder tank is overcharged for the cut-in setting of the pump. You can leak the bladder tank down or raise the cut-in setting of the switch. That should get things working like they are supposed to.
CJDave
Edited by CJDave (09/07/03 07:00 PM)
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chevdog
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Re: Follow-up on well water pressure
[re: CJDave]
09/08/03 07:45 AM
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I did use those type of directions to check and set the pressure switch settings - thanks.
CJ Dave, as one member of the general public who's not worried about barriers, this forum and the help that it offers are invaluable.
What you say makes good sense as to what's happening and what I need to do. The description of hydo/pneumatic helps me understand what's going on, especially that picture about the air bladder being off the bottom of the tank.
I'll double check the pressure switch settings and then start by increasing the cut-in psi incrementally. Great info - thanks very much!
Nick
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chevdog
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Re: Follow-up on well water pressure
[re: chevdog]
09/09/03 07:10 AM
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I went back and first lowered the cut-in pressure just to see what happened. The result was that the initial brief lag in water pressure became a 3 second delay. This goes along with what CJD had said. I then left the cut-out pressure (62 psi) alone, but then began to slowly raise the cut-in pressure. At 45 psi I could see that the lag in water pressure had almost gone, but not quite. Increasing it beyond this point really did not make a difference.
I did not tinker with the tank air pressure - it is set at 38 psi (reading taken with pump off, no water pressure). What I'm a little confused on is that when I take the reading with water pressure restored, the reading is lower than 38 psi, about 24-28 psi. If the bladder is being compressed, wouldn't the pressure reading be higher?
Also, does not having a control box make a difference in all this? The original 2hp pump had a Franklin box, the new 1.5 hp pump just has the wire from the pressure switch dissappearing down into the shaft. When the well company replaced the pump, they removed the box.
Thanks.
Nick
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CJDave
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Re: Follow-up on well water pressure
[re: chevdog]
09/09/03 02:14 PM
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At one time, most single-phase submersible motors were three-wire motors with the capacitors in the above ground control box. In later years, two-wire units were made such that they eliminated the control box and above ground capacitors. I always kind of preferred the control box models since you could more easily fix a no-start problem. That IS strange about the bladder tank having MORE pressure when the system pressure is zero than when it is at normal head. If I wuz you, I would definitely dump some pressure out of the bladder tank. As it is, you aren't getting the storage that you could have, small though it is. You don't want to be operating as close to "bumping" the bottom as you seem to be. The bladder will usually last longer if it stays up off the bottom just a bit.
CJDave
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chevdog
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Re: Follow-up on well water pressure
[re: CJDave]
09/10/03 07:28 AM
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I agree about the capacitor set-up on the pump - now if it loses a capacitor, it's turned into a service call to pull the pump rather than a 10 minute job for me to replace one in a control box. Dumb, especially since they got away before I got home to see this installation. The original 4" pump had the Franklin control box - the replacement 3" pump does not.
I let 2 psi out of the bladder tank, leaving the pressure switch settings alone and the lag in pressure is now getting reduced to a quick burp, so I think I'm creeping up to where everything should be set. There is a big improvement since the first day of this post  .
I will also double check the air pressure with the water on - sounds weird to me too. Then the well company and I will have a conversation.
Many many thanks for your help.
Nick
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CJDave
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Re: Follow-up on well water pressure
[re: chevdog]
09/10/03 01:45 PM
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Don't necessarily assume that a two-wire motor is somehow less worthy because I PREFER the three-wire type. It has been YEARS since I purchased a sub and who knows what technological breakthroughs have been made in submersible motor design. When I first got in the biz in 1967, just getting a sub to RUN under water was considered a huge accomplishment. We used to call them sub-miserables because certain makes gave SO MUCH trouble. Franklin emerged as the premier submersible motor company and it would be hard to fault one just at first glance. The big problem with residential water well work is that you are battling cost. The customer isn't usually knowlegeable enough to compare apples and oranges so low bidder wins. I generally avoided residential water supply work and only did it for my real good deepwell turbine customers and in that case, cost was not a factor so we went strictly cadillac, no corner cutting whatsoever. The problem with a lot of companies is that they get used to installing subs and don't know when to quit. Once you get to about ten HP, the low efficiency of the subs starts to cost you some real dough, and because they are 3450 RPM, any kind of a sandy well is blamo to the teensy tiny bowls and impellers. A marginal well is an application for a 1750 RPM lineshaft turbine; but you have to know how to install one ....of course.
CJDave
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