Pump not keeping up

[NoPlumberHere]

My pump does not seem to be keeping up with demand. A bit of backstory:

We came home from a walk and noticed a clicking sound. I saw the water pressure gauge fluctuating rapidly and realized the noise was the pressure switch (40-60lb) for our irrigation well - it was cycling very rapidly. Our well pumps to a pressure tank. I turned off the breaker, opened a hose, and measured the tank's pressure, which was zero. OK, bad tank. (It had previously lost some pressure, but I was able to pump it back to 38. And it was ten years old, and it sits the Florida sun. So I wasn't too surprised that the bladder gave up the ghost.)

Based on some advice I got, when I replaced the tank I upsized it, going from 43 gallons to 86. Doing that, I was told, would increase the run time for the pump (larger tank to fill) and would also increase the time between its runs since it takes longer for the tank to empty.

I pressurized the new tank to 38 pounds before filling it, as per its labeling. I turned the power on, and found no leaks in my plumbing - it filled up and held pressure and I saw no water anywhere. But when I turned on the sprinklers, I noticed the pressure dropping to just under 40 pounds and staying there; the pump is now having to run the entire time the sprinklers run. And while I can't swear to it, I am 98% sure that was not the case before; I am almost certain the pump cycled off and on during the sprinkler runs, filling the tank fairly rapidly. Running the pump the whole time the sprinklers are on is definitely not good. We have 9 sprinkler zones (a large yard), and each zome runs for 30 minutes. If I run just a single zone that is probably a 28 or 29-minute period the pump runs constantly, and if I were to turn them all on, the pump would run constantly for 4.5 hours. All that brings me to some questions.

1) Could the rapid cycling that happened (for who knows how long) have damaged the pump so that it no longer has enough power to adequately fill the tank?

and more important

2) What is my next step to diagnose and fix this issue?

Thanks so much for any help or advice!

Mike

 

[MicEd69]

Is this just for irrigation? Is the pump providing adequate flow for the intended use?

If the answers are yes to those questions, why do you think, "Running the pump the whole time the sprinklers are on is definitely not good."?

Cycling the pump very rapidly is absolutely not good at all as you stated. Good move on turning it off. But continuously running the pump is not a bad thing. It requires more power to pump water at a higher rate, duh. So, if your pump is cycling, it's using more power while pumping. As the pump is not hurt by running it continuously, as long as it has a flow of water (i.e. not dead headed), you don't really have a problem. Actually, some people go to variable speed drives and use the pump's speed to maintain their pump from cycling at all during use.

 

[NoPlumberHere]

Is this just for irrigation? Is the pump providing adequate flow for the intended use?

If the answers are yes to those questions, why do you think, "Running the pump the whole time the sprinklers are on is definitely not good."?

Cycling the pump very rapidly is absolutely not good at all as you stated. Good move on turning it off. But continuously running the pump is not a bad thing. It requires more power to pump water at a higher rate, duh. So, if your pump is cycling, it's using more power while pumping. As the pump is not hurt by running it continuously, as long as it has a flow of water (i.e. not dead headed), you don't really have a problem. Actually, some people go to variable speed drives and use the pump's speed to maintain their pump from cycling at all during use.

MicEd69, Hey - thanks for the reply. It is just for irrigation - we have water inside the home from our local utility. And no, the pump is not providing adequate flow, as once the pressure drops below 40 psi it stays there until the sprinklers shut off, and at that pressure, the sprinklers do not spray well. GREAT to learn I would not be hurting the pump to let it run continuously - I was concerned about that. And I have only tested a couple of zones, so I'm going to test them all now that I know I am not endangering the pump, to see if the other zones have the same issue. (The system was clearly not set up by somebody worried about creating equal pressure and flow among the zones; some zones are putting out much less water than others.)

Unless I hear from somebody with steps to diagnose the issue further (maybe the pump is running poorly? How do you tell?) I will go ahead and run it as it is, and see if I can find some reduced-flow sprinkler heads to replace what's in the ground now. If I can reduce the flow rate, that would allow the pump "get ahead" and actually refill the tank, and I would just run each zone for a longer period.

Thanks again!

Mike

 

[MicEd69]

OK. it just appears that your pump cannot produce enough pressure. But apparently it was before???

Cycling the pump will damage the motor, but they just burn out and die. Check the specs on your pump and see if you can determine if it is putting out the flow and pressure it should be. And if you have a way to check the amperage draw of the pump, that too may provide some good diagnostic information.

 

[NoPlumberHere]

That makes sense. And yes, my recall is that I previously saw it complete full cycles while the sprinklers were running.

Checking the pump's specs will (of course) be difficult. I have no information on it from the prior homeowner and have no idea what pump is at the bottom of the well. And while I can meter the amperage being drawn, I wouldn't think that would tell me much since I won't know anything about the pump.

A new question has popped up: How critical is the air pressure value in the tank? I ask because I checked it again (with the tank empty) this morning and it was at 36, which is a couple of pounds lower than where I thought I had left it. (It is a good bit cooler this morning...)

 

[Valveman]

And yes, my recall is that I previously saw it complete full cycles while the sprinklers were running.

Cycling on and off is the worst thing you can do to a pump, tank, pressure switch, check valve, and everything else in a pump system. Pumps are made to run 24/7/365. I have one that hasn't turned off since it was installed in 1999 pumping water to a stock tank. 30 years ago I also would have recommended a larger pressure tank. But you cannot put on a large enough tank to stop the cycling. Even with a large tank irrigation zones need to be large enough to use all the water the pump can produce to prevent the tank from filling and the pump from cycling on and off. As it is almost impossible to match every zone with the pump, adding a Cycle Stop Valve will solve the cycling problem. With a CSV the pump will run continuously as long as the zone is larger than 1 GPM. Cycling on and off wears out the pump, tank bladder, pressure switch, check valve, and everything else in the system. Cycling on and off means you sprinklers and shower is going from 40 PSI to 60 PSI over and over and over. A CSV would hold a constant 50 PSI no matter what you are doing. Constant 50 PSI in the shower feels so much stronger than cycling at 40/60 that people tell me they no longer even need soap in the shower. Also, constant 50 PSI means your sprinklers are hitting the exact right spot every time around, which they do not when cycling from 40 to 60 over and over.

All that being said, you probably only have a hole in the pipe above the pump. That is what will keep the pressure and flow lower than it should be. If you have a check valve at the tank, remove it. Then you can see the pressure drop when no water is being used, which will confirm a hole in the pipe.

 

[NoPlumberHere]

Valveman,
I enjoyed watching the video and learned a lot. Thank you! I believe I have a check valve of some sort, although I am not quite sure of its function. There is an "n" shaped piece of pipe protruding from the ground that, based on vibrations I feel only when the pump runs, must be between the pump and the tank. On that pipe sits a black,. somewhat mushroom-shaped device, and there are cutoff valves in the pipe both before and after that device. I've never actuated the cutoffs and candidly, I don't know why they are there. I had always thought the device was probably a back-flow preventer, but I really do not know its function and haven't yet found anyone who could explain why that part of the plumbing exists.

 

[FishScreener]

Pictures would help. “Black Mushroom”, says air relief valve to me. On down hole pumps, there is usually a check valve down near the pump. There should be another between the pump, and pressure tank above ground. But some folks don’t install one.

And a constantly running pump normally has enough water flow past it to dissipate heat from the windings when a pump runs. But rapidly cycling, puts the windings in the start phase where they generate significantly more heat than in the run mode. The pumps are configured so water flow cools the motor. It will take several minutes to flow enough water past the pump to cool it down. Thus short cycling the pump, heats the motor up and damages the windings. Short cycle enough times, and the windings get cooked.

Valveman is probably correct about a down hole leak in the lift pipe. Hopefully, your well is one they can easily get a truck to.

 

[Valveman]

Valveman,
I enjoyed watching the video and learned a lot. Thank you! I believe I have a check valve of some sort, although I am not quite sure of its function. There is an "n" shaped piece of pipe protruding from the ground that, based on vibrations I feel only when the pump runs, must be between the pump and the tank. On that pipe sits a black,. somewhat mushroom-shaped device, and there are cutoff valves in the pipe both before and after that device. I've never actuated the cutoffs and candidly, I don't know why they are there. I had always thought the device was probably a back-flow preventer, but I really do not know its function and haven't yet found anyone who could explain why that part of the plumbing exists.

Yeah or maybe a double check. Picture is worth a thousand words.

 

[NoPlumberHere]

I had an opportunity to examine the device and do a little web browsing. It is a Zurn Wilkins 1-720A Pressure Vacuum Breaker Assembly. After reading a bit about what those do, I really don't understand why it was necessary for it to be installed. Our well water system is only used for irrigation and our hoses. I mean, I'm not going to fuss that it exists, but does it really matter if there is backflow in a case where the water supply is only used for irrigation???

 

[Valveman]

Just irrigation or not, back flow can contaminate the aquifer. A faulty device like that could be restricting the flow. But I am afraid it is just masking the real problem which is a hole in the drop pipe.

 

[NoPlumberHere]

Just irrigation or not, back flow can contaminate the aquifer. A faulty device like that could be restricting the flow. But I am afraid it is just masking the real problem which is a hole in the drop pipe.

That makes sense. Thanks. And I decided that before going further, I should look at what happens when each of the seven zones on the primary timer runs, as my prior statement was from my observing what happened when zone 1 ran.

What I found was that the time it took for the tank to drop from 60 to 40 psi varied quite a bit from zone to zone, with four zones (including zone 1) each at around 50 seconds, one at 1:30, and the remaining two right at 3:00. The four zones that dropped the pressure in under a minute all resulted in the pump running continuously from that point, with pressure staying at 40 psi until they were done. The three zones that took longer to drop pressure all cycled the pump, with the run period ranging from 2:18 to 6:03.

Based on those results, I started thinking that maybe it has always been this way and that my observations of pump cycling were a result of timing - that I happened to be there when one of the three lower-output zones was running. And because I previously had a tank that was 1/2 the size of the new tank, the cycling I was seeing previously was happening in half the time it now takes. And that prompted some more thinking. . .

If the system has always done that, why am I seeing sprinklers not performing adequately when before they were ok? A couple of things occurred to me. First, I observed a few pop-up heads that have some amount of leakage around the pop-up. Second, I replaced several of the rotor-type sprinklers this past season. I didn't give any thought to flow rates and I may have installed replacements that use more water.

My plan now is to replace the pop-ups first to see what impact that has. And I likely will replace the rotors I installed in at least one zone where the coverage isn't what it should be, using rotors with modest flow rates, and see if those changes improve performance. But before I start that, I would be very grateful if somebody could tell me what I should accept as a minimum cycle time. While I now understand that short times are bad and that continuous running (if pressure is adequate) is actually best, I have no clue at what point a cycle is so short that it should really be concerning. My shortest off-time right now is in zone 7. The pressure drops to 40 PSI at 2:45, after which the pump runs for 2:15 before 60 psi is reached and it shuts off - so a total cycle time 5 minutes. That means that for the 45 minutes that zone runs, the pump will cycle 9 times. Should I be worried about that, or Is that cycle long enough that it is "ok"?

 

[MicEd69]

Valveman is the best person to answer this question, and I'm sure he will pretty soon. But the answer is there is no real "acceptable" minimum cycle time. The issue is that starting a pump is hard on the pump. So, your goal is to make that as few times as possible. A 5-minute cycle isn't too bad for every day or two or three, but listen to Valveman, he's the expert.

 

[Valveman]

Thanks MicEd! I don't know about "expert" but pumps are the only thing I know how to do. Lol! A properly charged 86 gallon tank will deliver 23 gallons of water as the pressure drops from 60 to 40. You can figure the GPM of each zone with the times you measured. For instance the zones that drain the tank is 50 seconds are doing like 27 GPM. If we knew what size pump you have we would know if this is correct. If you don't know anything about the pump, an amp check will tell you the horsepower and a bucket test will give you the GPM's. Of course the larger tank reduced the number of cycles by half. I also do not think the cycling reduced the output of the pump in anyway. A pump will cycle itself to death pumping full volume until it quits completely.

You can have leaks after the zone valves like around the pop ups and under the sprinkler heads. You could also have a leak in the pipe down the well, but that usually introduces air that you would notice coming from the sprinklers.

If the pump is doing as much as it is supposed to do, your big irrigation zones are putting out too much water and your smaller zones are putting out too little. Every zone needs to exactly match the pump to prevent cycling. This is almost impossible to do, which is what makes a Cycle Stop Valve important. Motor minimum cycle time is one minute on and one minute off, two minutes is better, and no cycling is best. One minute on and one minute off is designed to make the pump last just past the warranty period and no more.

 

[NoPlumberHere]

Thanks MicEd! I don't know about "expert" but pumps are the only thing I know how to do. Lol! A properly charged 86 gallon tank will deliver 23 gallons of water as the pressure drops from 60 to 40. You can figure the GPM of each zone with the times you measured. For instance the zones that drain the tank is 50 seconds are doing like 27 GPM. If we knew what size pump you have we would know if this is correct. If you don't know anything about the pump, an amp check will tell you the horsepower and a bucket test will give you the GPM's. Of course the larger tank reduced the number of cycles by half. I also do not think the cycling reduced the output of the pump in anyway. A pump will cycle itself to death pumping full volume until it quits completely.

You can have leaks after the zone valves like around the pop ups and under the sprinkler heads. You could also have a leak in the pipe down the well, but that usually introduces air that you would notice coming from the sprinklers.

If the pump is doing as much as it is supposed to do, your big irrigation zones are putting out too much water and your smaller zones are putting out too little. Every zone needs to exactly match the pump to prevent cycling. This is almost impossible to do, which is what makes a Cycle Stop Valve important. Motor minimum cycle time is one minute on and one minute off, two minutes is better, and no cycling is best. One minute on and one minute off is designed to make the pump last just past the warranty period and no more.

Valveman,

I thought about what you wrote (thank you again!) and it occurred to me that in addition to the cutoff box next to the tank, there is also a controller box. I looked at that and saw it is a "Pentek SMC-CR1521-02", which a quick google search tells me is a starter control box for 1-1/2 hp, 220v well pumps. While that obviously doesn't guarantee there is a 1.5hp pump in the ground, that certainly increases the likelihood that there is one of that size.

And, there are four wires - red, black, white and green, running in a twisted bundle from that box to the pump. There is an exposed portion of those 8g wires my wife dug up while gardening that's a couple of feet long (yes, I need to correct that, and no, I don't know why the prior owner didn't have the wires either encased in conduit and/or buried deeper <sigh>). I am pretty sure there is enough slack in the twisting of those wires that I can separate them and put a clamp meter around them individually. I should be able to do that tomorrow and will let you know what readings I get. I should also be able to time a 5-gallon bucket fill tomorrow - but I have a question. I don't have a 1-1/4 pipe open anywhere in the system, all I have is a regular spigot. Will the restriction caused by the spigot screw up the test? And I still won't know how deep the pump is, of course, but I am hopeful that if I can provide you with the amperage and the fill time (pending whether I can use a standard spigot or not), you will be able to make a better guesstimate of whether I am going to need to pull the pump and look for a leak in the pipe.
Thanks,
Mike

 

[Valveman]

With a 1.5HP pump, 27 GPM is very possible. Should be 11.8 amps. You don't want to check amps on the 4 wires going down hole but rather the L1 or L2 going into the control box, one of the inside two wires coming from the pressure switch, or one of the wires coming off the breaker. 11.8 amps would tell you the pump is putting out maximum capacity, and you are most likely losing some of it to leaks somewhere. Less than 11.8 amps would indicate a worn pump or clogged pump screen or impeller. You can bucket test from hydrants if you have enough to keep the pump running at max amps and low pressure. But if the pressure keeps climbing until the pump shuts off you do not have open enough hydrants to test the pump. If you need to open multiple hydrants to keep the pressure low, just measure buckets from each hydrant and add them together.