Water pressure problem when sprinklers on

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Old 08-04-07, 12:19 PM
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Water pressure problem when sprinklers on

Hello,

I have been having a couple of recent problems related to my water pump, water tank and the sprinkler system.

I have a water pump and 20 gallon tank with a 60/40 switch and psi gage attached. The sprinkler system was installed two years ago and has not been an issue until now.

The first thing I noticed is that the system (without the sprinklers running) had trouble making the 60 psi that would cut off the pump. When it got to 58 psi I could give the pressure switch a little tap or just cycle the power to the pump and the pump would stay off. This seemed like I might need to adjust the pressure switch or possibly replace it.

I later noticed that when the sprinklers were on, the pressure reading would drift downward to 40 psi and this would cause a short interruption every 15 seconds or so in the water going to the sprinklers (and anything else that was on). The system sort of recoils when this happens and the gage falls to zero very briefly before returning to around 40 psi.

I'm not sure if the two are related. I'm guessing this might mean the tank and bladder have seen better days (they are about 5 years old and have had no other signs of problems).

This has only occurred in the past few weeks and I've been running under the same conditions since day 1 with the sprinklers. I did try to change the pressure settings on the switch, but only the high end adjustment and I was careful not to move it too much.

Anyone have any ideas about this?
 
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Old 08-04-07, 12:40 PM
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Sounds like you are running out of water.

You do not even NEED a pressure tank to maintain constant (wellpump) pressure, - so that is not the issue. The fact you have the drop can only mean little water is making it's way to the tank. Either low table, or weakened pump where the horsepower has come way down, or hole in pipe is my guess.

For further input you may want to repost this under the wells sub forum just below this subforum.
 
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Old 08-04-07, 01:08 PM
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Ecman

Thanks for the suggestion re posting.

I'm hoping it is not the pump motor, but I guess the sooner I figure it out the sooner I'll deal with it.
 
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Old 08-04-07, 02:13 PM
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Originally Posted by jgrav8 View Post
Hello,


I later noticed that when the sprinklers were on, the pressure reading would drift downward to 40 psi and this would cause a short interruption every 15 seconds or so in the water going to the sprinklers (and anything else that was on). The system sort of recoils when this happens and the gage falls to zero very briefly before returning to around 40 psi.
Could you maybe rethink this paragraph, and pretend none of us have a clue to what is going on with the durations and water usage volume, etc., and explain this more? This paragraph may hold a better key as to what is happening. Be explicit how long it takes to drop from 40 down to 0, and then how long it takes for it to then climb from 0 back up to 40 while the sprinkler is on. And also you can try on another test, when it gets to 0, to see how fast it recovers to 40 and also to 58, if you turn off the sprinkler.

On a house I do work on, their well has a 1/2 hp submersible and I have done gpm testing and watching the gauge drop and found this house, with a high setting of 56 psi and a low setting of 40, can only sustain 40 psi, when 2 showers are being run at the same time and consume 3.75 gpm's. And if more than that is used, the pressure drops and drops below that to 20, etc. And they too have a sprinkler system, that after it runs for like 1/2 hour, no longer has enough water pressure to do anything. The pressure keeps slowly dropping because the well pump output just is not enough. And their well was redug/new pump put in! Their problem I have concluded is they need a bigger hp pump down there. Their problem did not just suddenly occur, either. It has been that way from day one. They have 1" copper pipe from the well and this should be able to handle plenty of water volume at near 60 psi + of well pump force (20-30 gpms perhaps).
 
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Old 08-04-07, 02:19 PM
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Do you notice if the pressure goes high after the pump turns on? Meaning above 60 psi? Sometimes what happens is the tube between the tank T and the switch gets clogged. What can happen is that it takes longer for the actual tank pressure to reach the switch would can cause a delay in turning on and off. So if the tank pressure is 40psi, the switch might still think its 55psi. It will slowly equal out. The same thing happens when the pump turns on. It might fill the tank to 70psi but the switch only thinks its 50psi because of the clogged pipe. It will get to the point where the switch won't do anything at all or constantly blow your relief valve. If you need to clean the tube. Turn off the power to the whole pump system and remove the wires from the switch(mark where they came from). Be sure to get a bucket of water first. After taking the wires off, unscrew the tube from the T then unscrew the tube from the switch. Take a zip tie(or something) and clean out the tube then rinse it with the bucket of water. Then put everything back together with tephlon tape.
 
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Old 08-04-07, 08:21 PM
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Originally Posted by ecman51` View Post
Could you maybe rethink this paragraph, and pretend none of us have a clue to what is going on with the durations and water usage volume, etc., and explain this more? This paragraph may hold a better key as to what is happening. Be explicit how long it takes to drop from 40 down to 0, and then how long it takes for it to then climb from 0 back up to 40 while the sprinkler is on. And also you can try on another test, when it gets to 0, to see how fast it recovers to 40 and also to 58, if you turn off the sprinkler.
Ecman51, good point. I think I was trying to get to the problem without writing something too long, but to describe this further:

The drop from 40 down to zero happens very quickly, as if the supply is choked off (as you had referred to in a previous post). It rebounds up into the mid 30's for psi also very quickly, within a few seconds. From there the gage moves rather slowly to around 40 psi. This cycle repeats itself over and over until the sprinkler is turned off. At that point, the pump continues to run and builds pressure to a bit less than 60 psi. With the sprinkler turned off, there are no more interruptions as described -- the pressure builds steadily.

I have adjusted the setting on the pressure switch so that it cuts out at around 58 psi now. To go from 40 psi to this setting is around 3 or 4 minutes. Previously, the pump would build pressure to around 58 in about the same time frame but be stuck there and not able to make it to 60 where the original cut-off was.

adamplghtg, I have never seen the pressure shown on the gage above 60 psi. When the pump turns on the psi is at 40 and it does not spike, it gradually builds toward 60. This has not changed.

Thanks for the tips about cleaning out the tube. A likely next step for me is to open this up and check for an obstruction/clean it out.

After posting earlier, I did put the sprinklers back on and observed a little more outside. The pattern had been about every 15 seconds or so that the line appeared to be interrupted, but after going on for a while this got much worse (like every two or three seconds) to the point where I just shut them down until I get a bit further.

I also checked on the motor size. I have a small control box mounted near the tank and fed from the 230v connected to the pressure switch. This is a Franklin Electric model 2801074915 controller. This contains a capacitor and what looks like a solid state relay, along with terminal connections. It is rated at 3/4HP and the incoming line is 1".
 
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Old 08-05-07, 12:44 PM
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It sounds now like you have 2 problems. Insufficient water supply based on what I already have said, AND a waterlogged pressure tank which accounts for the sudden drop and rebounding.

IF your well were actually able to recover so quickly as to raise pressure from 0 to 40 psi in a few seconds, then your wellpump output would be so great you wouldn't be having your water volume issue. Therefore I think you have the two problems simultaneously.

Do you have a bladder style pressure tank? These arre often propane gas tank shaped and are often blue or beige and have the name of the unit end in " ___trol".

If you have such a tank, to find out what is going on, you would shut off your wellpump circuit breaker, shut off the water valve coming out to the distribution of your house, hook up hose to drain valve coming out near bottom of plumbing by pressure tank, drain water til gauge says 0, then use tire gauge and take reading off the schrader valve (valve like bicycle and car tires have) and the reading is supposed to be 2 psi less than what your well's kick-on set point is. (i.e., if well kicks back on at 40, your schrader valve reading should say 38).
 
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Old 08-08-07, 06:23 PM
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OK, I've spent a little time getting in touch with those who installed the systems in question.

Ecman51, to answer what you had asked in the previous post, yes the water tank does have a bladder. It is a Well-X-trol tank, model WX-251.

I spoke to the guy who installed the well and we went over the situation. I figured there may be a leak in the system somewhere. He is convinced it is a water table issue. Ecman, I read your reply in the Well subforum regarding the water table around the Great Lakes and I live in southeastern Michigan. It makes sense. None of my neighbors have this issue right now, but they haven't really been watching their systems when the sprinklers are on (they will now though).

The details on the well are that it is 135' deep with the head around 80'. The motor is 3/4 HP 20 gallons per minute. The well guy stated he could move the head down about 20' and put on a 1HP motor with similar output for around $1000.

It seems that this is the issue when the sprinklers are on as the system behaves like it is starved for water.

Thankfully we've had a good amount of rain here the last few days and I've kept the sprinklers off (and will as long as I can).

Not sure if you guys have any other thoughts. I'll do the check out on the tank this weekend coming up.
 
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