+ Reply to Thread
Results 1 to 9 of 9
  1. #1
    Join Date
    Jun 2008
    Posts
    4

    Default Pump starts with a bang

    We have a Sta-Rite Signature 2000 4” ¾ hp submersible water pump. The well is 227 feet deep; the water level is at 110 feet and the pump is down 147 feet. The pump is connected to an Amtrol Well-X-Trol bladder water tank. The Square D pressure switch is set to cut in at 40 PSI and cut out at 60 PSI. The tank pre-charge is 38 PSI.

    I have verified that the above pressure settings are correct by following the procedure in the Signature 2000 owner’s manual available here: http://www.onga.com.au/secure/downlo...fileid=1001397

    TO CHECK PUMP PRESSURE SWITCH SETTING
    1. To check pressure switch setting, disconnect power to pump at supply panel (but be sure to leave pressure switch connected to power supply wires).
    2. Remove pressure switch cover.
    3. Open a faucet near tank.
    4. Allow water to drain until pressure switch contacts close; immediately close faucet.
    5. Check pressure at valve with standard tire gauge or with pump pressure gauge (if supplied).
    6. Pressure gauge should read at pump cut-in setting (30 PSI for 30-50 switch, 20 PSI for 20-40 switch, etc.) If not:
    • Adjust switch according to switch manufacturer’s instructions.
    • Reconnect power supply to pump and pump up pressure in system.
    • Disconnect power supply to pump again and recheck switch setting.
    • Repeat until pressure switch starts pump within ±1 PSI of proper setting.
    • If cut-in setting is too low, system will rattle or develop water hammer when pump starts.
    • Cut-out setting is not as critical as cut-in setting. Make sure that pump will stop running in a reasonable time. If it does not, cut-out setting may need to be adjusted down slightly. Be sure that after readjustment, system does not rattle or hammer on startup.
    1. Re-check tank air pre-charge to be sure it is 2 PSI below pump pressure switch cut-in setting.

    When any upstairs faucet is drawing water and the pump starts, it starts with a bang (water hammer). On the other hand when I open the faucet located below the pressure gauge to draw down the water, the pump starts quietly when the cut-in setting is reached.

    What is causing the water hammer at pump startup, and, more importantly, how do I get it to stop? Why would a low cut-in setting cause a water hammer?

  2. #2
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,557

    Default Re: Pump starts with a bang

    When you checked the pressure in the bladder tank, did you do it when there was no water in it?
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
    Join Date
    Jun 2008
    Posts
    4

    Default Re: Pump starts with a bang

    Quote Originally Posted by JLMCDANIEL View Post
    When you checked the pressure in the bladder tank, did you do it when there was no water in it?
    Jack
    Yes. I shut off power to the pump and opened the faucet beneath the pressure gauge until the water stopped. Then I checked the pressure in the tank and adjusted it to 38 PSI. I also tried adjusting it to 36 PSI and noticed that the bang was not quite so loud.

    Incidently, while searching through this forum, I found this from a member named ****hiller: Ideally, the precharge of a pressure tank should be approx. two lbs less than the turn-on setting of the pressure switch. The charge is adjusted after turning off the pump, drawing down the tank just till the pressure switch clicks (stop drawing water immediately) and then raising or lowering the precharge air pressure......if it needs adjustment.

    I'm not sure if I understand, but these directions seem to imply that there is still some water in the tank when you adjust the air pressure.

    It would be nice if a plumbing guru could explain what exactly is causing the hammer; that is, when the pump starts and begins to fill the tank, what is it precisely that produces the sound and why doesn't it occur when the faucet beneath the pressure gauge is open? In that the manual directions warn about a water hammer, I assume that the plumbing industry is well aware of how to deal with it.

    Of course, having said that, what I really would like to know is how to get it to stop.

  4. #4
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Pump starts with a bang

    wagtail,

    (Raises hand and admits error in previous post)

    That was me and I mis-spoke. Not a good excuse for doing that, but sometimes I've posted when it's
    late or I'm fried-out tired or distracted by other things. My bad.

    You do indeed want the tank totally devoid of water when checking the precharge.....whether that tank is a bladder
    type or a single compartment galvy tank.

    If we look at the cause of water hammer, it's basically water in motion (having kinetic energy) that has a door slammed in it's face, leaving it nowhere to go. Water is non-compressable. It's like you or me running full tilt into a
    concrete wall. Bang. This is what hammer-arrestors are for. They absorb the shock of that sudden stop so no
    bang occurs.

    Generally speaking, your pressure tank should/will act as a big hammer-arrestor for the entire system in your house..............provided the tank isn't water-logged. (has no air head in it) We already know that a water-logged tank isn't likely the case......... because you have properly drained the tank and injected air to meet the proper/ideal pre-charge for your particular pressure switch (2 lbs less than trip-on point
    of pressure switch). Note - If you had a little too much pre-charge in the tank, the pressure switch wouldn't ever
    reach the trip-on point and consequently the well pump wouldn't start. This is not the case; your well pump does
    start when you consume water from the tank.

    Water hammer usually occurs when a valve/faucet somewhere is suddenly closed. Yours, however, occurs when the pump starts. But the principles/causes of water hammer remain the same; water in motion (kinetic energy) that doesn't have a escape route.......or an *adequate* escape route.

    You state the diameter of your well pump & the HP rating.............but not the size of the pump itself. A submersible well pump consists of two basic parts; 1- the motor to drive the pump & 2- the pump itself. You can buy pumps that
    deliver 4, 6, 8, 12, etc....... gallons per minute. (The actual gpm delivery of any given pump will vary according to how
    far it has to lift the water, but we won't go there...yet ) Yours is likely either a 4, 6 or 8 gpm pump.....unless it was
    sized for a sprinkler system in which case it may be larger yet.

    Another consideration is the velocity of the water in the pipes. This too will vary, but the basic concept is all we
    need here.....I think. The faster the water is moving when the door is slammed, the greater the water-hammer. So we have .........the volume of water being pumped in a given amount of time..............& the velocity of that water.

    Looking at your picture ....what I think I see is a 3/4" delivery pipe from the well pump emerging from the floor and a 3/4" pipe entering the tank. If this is the case, I'm betting this doesn't meet the requirements for your wellpump. Unless your pump is only delivering 2 or 4 gpm.....I'm betting the manufacturer's specs require a minimum of 1" supply/delivery pipe both from the well and into the tank. 1 1/4" is also common and recommended for these common sized residential pumps.

    A smaller pipe will increase the velocity of the water (think putting your finger over the end of a garden hose to
    increase the velocity of the stream) ............encouraging/promoting water-hammer....if that water lacks an adequately accomodating "receptor". I *think* this may be the cause of the problem in your instance. Not that your tank size is inadequate, but rather that the path/pipe into it may be inadequate to the output of the pump.......or that the pipe down-sizing transition is too radical. I'll get to that in a minute.

    For the sake of discussion, I'll yak a bit again about pump curves. Remember when I said that any given gpm pump can/will actually deliver a different amount of water depending upon how far it has to lift the water? The distance the pump has to lift the water is the distance from the static water level in the well to your storage/pressure tank. The well pump manufacturer provides pump performance curves for their various offerings and you must choose a combination of motor and pump that meets your needs/requirements. (Should also be matched to the size of the
    pressure tank so that the pump runs a minumum of one minute between cycles) Too small of a motor or pump, not a good thing. Not enough umph to get the job done and the motor and/or pump are overworked..........or fail to get the job done at all. Too big of a motor or pump, also not a good thing. In this scenario, you'll likely short cycle the pump/motor, overheating them.....unless you have a really big pressure tank/storage vessel.

    If you look at a pump curve chart for any given pump you'll see that as the lift distance changes, the amount of
    delivery changes. And you'll see that there is an acceptable range for any given pump. This is the acceptable range
    without overworking or causing cavitation of the pump (Cavitation is not good thing and will ruin the pump in short
    order. Google .......well pump cavitation......for more info) However, as long as delivery from the pump remains within the parameters of the accepted curve chart.....we're good to go. This means that we can actually choke down the delivery of a pump in a given situation....IF we desire to or need to for some reason..........so long as we remain within those curve parameters. This is what throttling valves are used for.........whether those be manually adjusted throttling valves (common gate valve) or automatic throttling valves.

    So..........if throttling within the accepted range is okay............ we might then assume that your 3/4" pipe is simply acting as throttling valve and if the resulting output falls within the accepted pump curve.........all is fine and dandy and there should be no resulting water-hammer or over-working of the pump/motor. However, from afar......I'm thinking/conjecturing that the transition
    from the largest pipe (likely 1 1/4" or 1/1/2") that your wellpump is hanging on down in the well to the smaller copper
    pipe is too drastic for too great of a distance.......and could well be the cause of the water-hammer.....even if the
    resulting pump output is within acceptable range. IOW, the pump is initially and momentarily moving lots of water in that first section of larger pipe and then that water runs into a partially closed door (the 3/4" pipes from the well and into the pressure tank). Water hammer results.

    When you open the valve/faucet right by the pressure tank
    you're giving this "excess" water somewhere to go. That open faucet provides an additional/immediate relief above, beyond ....and BEFORE......what the 3/4" line into the pressure tank accepts. I'm thinking that a potential reason the water-hammer happens if you open a faucet upstairs...... is that there is, of course, additional head pressure and friction in those pipes and that perhaps those are also flow-restricted faucets.
    Therefore the relief isn't quite the same as there is more resistance to flow in that route. Perhaps just enough to
    cause the water hammer when the pump kicks on.

    I'm also going to assume that the branch pipes to the fixtures upstairs are 1/2". So there's additional restriction to flow when you open faucets up there.

    Does this also happen when you open the tub valve? Reason I
    ask is because tub valves usually don't have any restrictors in them. (Shower heads, yes. Tub valves, no) If having the tub valve open doesn't result in water-hammer, then perhaps all you need to do is remove the restrictors from the offending upstairs faucets. IOW, your system may be living on the very edge, so to speak. If you can remove the straw that's breaking the camel's back.........the problem may disappear/be remedied without re-piping anything.....or changing to a well pump with a lesser gpm output.

    Even if you can rid yourself of the water-hammer by removing faucet restrictors, I'd still suggest you check out the
    pump curve chart against the actual delivery from your current well-pump to make sure that you aren't overworking it with too small of delivery pipes. If you are, that will greatly shorten its life expectancy.
    Last edited by goldhiller; 06-06-2008 at 11:53 AM.

  5. #5
    Join Date
    Jun 2008
    Posts
    4

    Default Re: Pump starts with a bang

    Thanks so much for attempting to educate me on some of the subtleties of pumps and pipes; I found your reply both informative and interesting. Let’s see if I can fill you in on some of the questions you posed: First, all of the copper pipe you see in the picture has an OD of 1.125 inches; thus, according to http://www.sizes.com/materls/pipeCopper.htm it is commonly called 1” pipe. The Well-X-Trol tank documentation that I have indicates that 1” pipe is the recommended size for a flow of up to 16 GPM.

    The model number of the Sta-Rite pump that I have is 10P4D02T-02. Unfortunately, none of the documentation that I have indicates the GPM flow rate and the Sta-Rite web site ( http://www.starite.com/ ) does not have any information on this particular model number. Most likely it is no longer in production.

    You are correct that the bath tub faucet is the outlet that seems to flow the greatest amount of water; it is fed by ¾” pipe. I let it run wide open until the pump cut in. It still kicked on with a bang.

    My first thought was to install a hammer-arrestor near the tank, but it occured to me, just as you mentioned, that the pressure tank itself should/will act as a big hammer-arrestor.

    I'd like to be able to locate the source of the bang itself; that is, somehow trace the noise to a particular piece of equipment. Is this even remotly possible?

  6. #6
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Pump starts with a bang

    Quote Originally Posted by Let’s see if I can fill you in on some of the questions you posed: First, all of the copper pipe you see in the picture has an OD of 1.125 inches; thus, according to [url
    www.sizes.com/materls/pipeCopper.htm[/url], it is commonly called 1” pipe. The Well-X-Trol tank documentation that I have indicates that 1” pipe is the recommended size for a flow of up to 16 GPM. ?
    Well, dang. What I thought I saw (3/4" pipe) .....isn't so. If it's 1" ID pipe, it's not likely the cause of or a significant contributor to the WH you're experiencing.

    [QUOTE= The model number of the Sta-Rite pump that I have is 10P4D02T-02. Unfortunately, none of the documentation that I have indicates the GPM flow rate and the Sta-Rite web site does not have any information on this particular model number. Most likely it is no longer in production. [/QUOTE]

    There's a relatively easy way to check the delivery rate of the pump with a bucket and a watch, but we won't go there right now.


    [QUOTE= You are correct that the bath tub faucet is the outlet that seems to flow the greatest amount of water; it is fed by ¾” pipe. I let it run wide open until the pump cut in. It still kicked on with a bang. [/QUOTE]

    Dang again. <G>


    [QUOTE= I'd like to be able to locate the source of the bang itself; that is, somehow trace the noise to a particular piece of equipment. Is this even remotly possible?[/QUOTE]

    Yes.............maybe......probably. <G> It depends.

    Let's go somewhere different in the hunt for the WH. Do you know what type of pipe your pump is hanging on in the well? If it's hanging on black poly pipe.......the following possibility becomes more suspect than if it's hanging on galvy or rigid PVC pipe.

    When a pump kicks on there is torque from the motor/pump. This torque/twisting action transmits to the pipe it's hanging on and without any restriction can/will bang the pump against the inside of the well casing. The remedy/prevention for this is to install a torque arrestor/dampener at the pump and perhaps a few wire guards on the pipe in the well casing. I've pulled a few non-functional pumps from wells which were hung on black poly ......with no torque arrestors/dampener.... to find that the whole business had been thrashing around like a boa constrictor .....so badly that the power wires were rubbed clean thru/broken as a result. However........to the best of my remembrance......none of these situations resulted in discernible noises inside house. Or at least the HO didn't say anything about that to me.

    If your pump is instead hung fairly deep on galvy pipe........but without any torque dampener.... I suppose there's an outside chance that it could be the source of the WH you hear...although torque dampeners aren't usually used/needed with galvy, IME. Be that as it may, the galvy would transmit noises better than the black poly-pipe. This diagnosis stuff is really hard from afar.....in this instance. <G>

    Has this water system always done this?....or did it start after you changed something in the system? Or is this a new house to you and you have no idea if it always did this?

    I'll chew on it some more. There's always an answer/cause. Finding/identifying it without being on site makes it ever more difficult. <G>
    Last edited by goldhiller; 06-07-2008 at 09:59 AM.

  7. #7
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Pump starts with a bang

    Here's another possibility:

    Do you have an "above-ground" check-valve on the pipe from the well? If so, removing it may put an end to the WH.

    What may be happening is that there is already a check-valve down at the pump. Usually is, anyway. If a second check-valve is placed in the line and the one down at the pump is failing/leaking back....... that will create a void in the pipe between the pump and the upper check-valve. When the pump kicks in, the water rushing up the empty line slams into the water waiting at the upper check-valve. Bang. Opening the valve in front of the pressure-tank may very well provide an adequate/additional path of relief for the force of this collison and so you don't get the bang.

    *If* this second check-valve exists and you don't know why it's there....it may have been installed because the one down at the pump had begun leaking back. If the one down at the pump leaks back, it will cause/allow the pressure tank to also drain back down the well casing. So......the cheap & dirty "fix" to prevent the pressure-tank from draining back was to install a second check-valve. (Didn't want to pull the pipe & pump to find and fix the real cause.)

    The initial indication that a check-valve at the pump is leaking would be "phantom" cycling of the wellpump (no one and/or no applicance is drawing water, but there is a call to replenish the tank because the pressure has dropped) Note - A crack/hole in the delivery pipe from the wellpump can/will also lead to the same or similar symptoms...... and may also have been the cause for installing a second check-valve...if one exists.

    Point being, if you remove an above ground check-valve .....you may find yourself with no more WH, but have some phantom cycling of the wellpump. If so, you'll know where to start looking for the cause of that.
    Last edited by goldhiller; 06-07-2008 at 11:39 AM.

  8. #8
    Join Date
    Jun 2008
    Posts
    4

    Default Re: Pump starts with a bang

    >> Do you know what type of pipe your pump is hanging on in the well?
    No. My knowledge of the system is limited to the documentation and manuals that I have and what you see in the picture above.

    >>If your pump is instead hung fairly deep on galvy pipe........but without any torque dampener.... I suppose there's an outside chance that it could be the source of the WH you hear.
    That the pump starts quietly if the faucet below the pressure gauge is open would seem to rule this out, would it not?

    >>Has this water system always done this?
    No. The water-hammer seems to be louder in intensity, but that may just be my imagination now that I have become fixated on it. The house and its systems are going on 14 years old now, and various systems are beginning to fail and/or require service; apparently the water system is just one more device in need of attention.

    >>Do you have an "above-ground" check-valve on the pipe from the well?
    I do not know. If it does not appear in the picture above, then I have no idea. The water system was installed in the fall of 1994. It has not been touched by a plumber since its installation. The only thing I have ever done to the system is to check and adjust the pressure in the tank from time to time.

    >>The initial indication that a check-valve at the pump is leaking would be "phantom" cycling of the wellpump.
    To my knowledge, this does not occur. The only time the pump starts is when a faucet is open.

  9. #9
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Pump starts with a bang

    That the pump starts quietly if the faucet below the pressure gauge is open would seem to rule this out, would it not?

    Probably.

    Can't say/see from here what your exact setup is, but........I'll presume that you don't have a well-pit because you haven't mentioned one.....and because your pressure tank is located in the basement. (However..... we have a well-pit, but our pressure tank is also in the basement because I prefer it that way. Much easier installing and servicing the tank that way.) I suspect if you had a well-pit, you'd know it and would've said so. And so I'll assume you have a well casing that emerges a couple feet out of the ground and the water line connects under the ground via a pitless adapter. Not much chance of having a second check-valve in that type of setup....unless it's right there by the pressure tank and I don't see one in the pic.

    Therefore......I'm now gonna guess that the "WH" you hear is likely/actually a line inside the house that's flexing/rattling/banging against a joist, stud or similar when the surge of water comes at pump kick-in time. If you look at the piping arrangement down by the tank you'll see that the water coming from the pump has a straight shot to the main branch supplying those upstairs fixtures........but would have to turn a corner to enter the pressure tank. The surge will have a natural tendency to follow the path of least resistance.

    It's not that unusual for pipe brackets to come loose after a while.....particularly if those brackets are nailed rather than screwed to the joists/studs. The pipe(s) to investigate would be the one(s) that is/are common to the fixtures that cause the "hammering" noise when the pump kicks in.

    Although a sticky check-valve down at the pump can also cause WH when it opens...... if that was the case....... you should get the same noise whether you open the valve at the pressure tank or anywhere else in the house. I think that can be ruled out by the evidence.
    Last edited by goldhiller; 06-09-2008 at 10:29 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •