Occasional (very) Low Pressure with submersible pump

Plumbing Forums

Help Support Plumbing Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Beshmo_Handes

Member
Joined
Jan 24, 2016
Messages
11
Reaction score
1
Location
,
Hello, I'm new to the forum.

I read through several postings, but haven't yet seen a problem description that matches up with mine. This is a submersible pump, with a 30/50 pressure switch.

I've noticed lately that my water flow will drop to a trickle, and it seems the only way to get pressure back is to turn off the demand and wait a few minutes. I initially suspected the water filter (after the tank and before the softener) was causing a pressure drop - it was a 5 micron filter. I replaced it with a 30 micron filter, but the issue remains. I do get some clay/brown deposits near the bottom of the filter, though this has been the case since I moved in (3 1/2 years ago). At that time, I replaced the pressure tank, pressure switch, and filter housing assembly. No issues with it until now. I also added a indicator lamp on the motor controller that lights up when the pump is running.

I checked my pressure gauge once when the pressure was low, and the gauge indicated 10 psi. The pump was running at that time, so it may have dropped even lower than that before I saw it. I watched it slowly increase for a few minutes to about 20 psi, and then eventually the pump shut off as normal. I opened a sink beside the pressure tank and switch, and watched the pressure drop down to 30 psi, at which point the switch clicked on, and the pump ran. I shut off the faucet at 30 psi, and timed about 13 minutes until full pressure of 50 psi was reached. My well is 98' deep, and is marked "8 GPM". It seems like the low pressure is only an issue if demand continues after 30 psi is reached.

Tank pressure reads about 28 psi when the pressure switch activates.

I suspect that the pump inlet has a blockage that is limiting flow to the rest of the system, but I'm not an expert by any means, and if you have another idea, let me know!

TYIA, and sorry for the long post.
 
Last edited:
Is it a 1/2 horsepower pump? Take an amperage reading when it's running. At that depth you should get a reading anywhere from 5.5A to 7A. If you are in that area and still getting low pressure, I'd say the impellers are toast, time for a new pump.
 
Good idea!

Yes, it's a 1/2 HP, at least that's what the motor controller is rated. There are three wires coming out of the controller - red, yellow, black.

yellow reads 4.6 to 5 amps.
black reads 4.6 to 4.9 amps.
red reads 0 amps. I assume this is the ground wire?

I agree with your diagnosis. If there was a blockage to the inlet, I'd expect to see higher amp draw from the motor trying to work harder.

Next question: Does impeller wear indicate something abnormal (sediment), or is this expected wear? I don't know if this is the original pump or not (house built circa 1987).

Anyone have suggestions on a good pump replacement? I expect I'll have a professional confirm the problem and replace the pump.

20160124_093644.jpg

20160124_093732 (1).jpg
 
Last edited:
Your motor has two windings.....run and start.

Red and black are your start windings. Just like the starter of your vehicle, power is only present here for a fraction of a second until the pump ramps up, then it kicks over to your run winding, which is your black and yellow wires. Black is common between the two.

Impeller wear is common for wells with high sediment content. But most pumps use plastic impellers, not brass, so they just don't last like they used to.

There are housings for your pump that basically act like a sediment filter, that may be something to ask your pump installer. If all else fails, ask your wife for an old pair of panty hose ;).....or use a pair of your own...its 2016, we don't judge!
 
Unless you have a monster of a tank, 13 minutes is outrageous. One minute is more like it.

Hold the plate under the springs of the pressure switch down and see if it will make 60 or 70 psi. If it will, its not the impellers. Sometimes the poppet of the check valve can come loose and get stuck in the first joint of pipe above the pump. Acting like a valve. You could also have a low producing well or a plugged well screen, but if either were the case, the pump would pull the water below it's inlet and the flow from the pump would stop for a few minutes or so.

How old is the pump? You could also have a hole in your drop pipe, but if that were the case, it probably wouldn't make 50 psi.
 
Good information, thanks! The tank is a 36 gallon (I believe the drawdown is something like 11 gallons at 30-50 PSI).

If I understand correctly, a check valve malfunction would require replacement of the pump too, right? I will have to see if I can hold down the plate (not sure I understand how to until I see it). What you say makes sense, if the impellers were worn, they couldn't create as much pressure, but if there is a blockage, the pump will continue to push past the blockage until full pressure is built.

If the well was not producing like it used to/plugged well screen, would the pump suck air and would I see bubbles in the filter housing?

If there is a sediment issue, would it make sense to cut off a foot or so of the drop pipe to get the pump away from the bottom? I realize this would be giving up another foot of water.

I don't know how old the pump is. I've lived here about 3 & 1/2 years, so it's at least that old. Could be as old as 1987.
 
Last edited:
If I understand correctly, a check valve malfunction would require replacement of the pump too, right? I will have to see if I can hold down the plate (not sure I understand how to until I see it). What you say makes sense, if the impellers were worn, they couldn't create as much pressure, but if there is a blockage, the pump will continue to push past the blockage until full pressure is built.
A bad check valve doesn't cause you to buy a new pump, but you would have to pull it to repair it, so installing a new one at that time may be more cost effective. Most of the cost is actually labor. You'll see the springs on the switch, they push on the plate. Pliers would help. Correct on the pressure and blockage issue.

If the well was not producing like it used to/plugged well screen, would the pump suck air and would I see bubbles in the filter housing?
The pump will not suck air. It will simply run out of water to push up.
If there is a sediment issue, would it make sense to cut off a foot or so of the drop pipe to get the pump away from the bottom? I realize this would be giving up another foot of water.
No, the sediment is coming from wherever and is being moved with the water flowing into the well somewhere. Moving the pump will make no difference.
 
While you are here, would something like this - http://www.lakos.com/gwi-products/sub-k - be helpful if one had a heavy sediment problem in the well?
__________________
In my experience when the brand was Laval Seperator, they worked very good with coarser material, but with very fine sand, the sand would not come out of suspension quick enough and would pass right through into the plumbing. So it would depend on the size of the material. I am not sure how they get rid of the sand that the sub unit catches. The above ground device had a valve on the bottom to empty the sand out.
 
I held the switch on, and watched it build pressure to just past 60 psi. I stopped there. For some reason, the picture is upside-down no matter how I rotate before uploading.

Out in left field question: with a depth of 98 feet, could I convert to a deep jet pump, rather than submersible? The advantage seems to be that the pump would be accessible from within the house. What would the disadvantages be? Just weighing options.


Also, do the submersible pumps have a standard pipe size, or do I need to know what it is before buying one?

20160127_1931392.jpg
 
Last edited:
How long did it take to reach 60psi?

Jet pumps can be real contankerous bastards. I hate them. I can't in good conscience recommend that you convert it over, you're going back in time, and making a lot more work, as you will need both 1" and 1 1/4" pipes going down the well to the injector housing. The pump may be in the house, but the injector down the well will give you problems in the future too. Stick with the submersible you are better off.

In my area, the majority of pumps come standard with an 1 1/4" female tapping, with 1" well pipe. So along with a new pump you need an 1 1/4 brass male x barbed fitting
 
No problem, I just turned my monitor upside down.:)

Forget the jet pump idea, it's a bad one. I don't think there is anything wrong with the pump itself. If you knew where the well was and could cut the pipe feeding from the well to the house then run the pump wide open on the ground, you could get an idea how much water it's moving. It should come out of a 1-1/4" pipe full. If it's just trickling out, there is a restriction, probably the pumps check valve as mentioned earlier.

As for buying pumps, you need to know which one you have. Horsepower as well as the pump end's gallon per minute rating. It could be 4, 5, 7, 10, 15, 18 etc. Getting the right one is important.
 
If the check valve is gone in the pump, the pump would cycle on and off
Not necessarily. I have seen them where the nut that only allows them to open so far to break off allowing the poppett to go further up into the drop pipe practically stopping flow altogether. Then closing normally when the pump turns off stopping the water from going back through the pump. I'm 87% sure that is what's going on.
 
Follow up:
Pulled the pump today. It was covered in orange gunk. The well casing is pretty rusty. The drop pipe was filled with orange sludge, probably down to ½ diameter opening. Had a buddy to help.

Basically everything below the pitless adapter is new now (re-used the wiring and cable guides). We also took the time to measure the depth of the well, and the depth of the water. We moved the pump up a few feet, after calculating the volume difference would be about 5 gallons less of usable (pumpable) water. The reason was to get away from the area the old pump had been knocking against. Maybe not necessary.
We replaced the pump with an equivalently sized one. Installed a brass check valve after the pump – I removed the plastic one that was built into the pump.

Replaced the drop pipe with 160 psi black poly, which had a thinner wall than whatever was there previously.
No torque arrestor had been installed on the old pump, and there was visible scarring on the pump where it seems to have been jumping around inside the well, knocking into the wall.

The pitless adapter o-ring was damaged, so I got a new pitless adapter and just used the o-ring.
We installed a torque arrestor, dropped it back in, and turned on the garden hose. Lots of pressure, lots of gunk came out. I believe this would have been crud that had settled in the pipe to the house.

Also pumped up the pressure tank a bit, as it was down to `22 psi when completely drained (pressure switch is set to 30/50). I believe I may have bled some out with all the troubleshooting I've been trying to do.

All in all, pretty smooth process, with one kerfuffle:

Once the water ran clear, I wanted to sanitize the well. I calculated the amount of bleach to use based on the volume of the well. With the pump running, I mixed a 5 gallon bucket with some water and bleach, and poured it down the well. Almost immediately, the output from the pump was reduced significantly. I believe pouring in the water knocked some stuff loose that got sucked into the pump. Pulling the drop pipe again, but only a few feet, then pumping the whole thing up and down a few times. cleared whatever was clogging the inlet. Now flow is great.
I may have been able to do just the up-and-down to the old pump, but I’m glad the drop pipe is now completely clear.
All in all, about 6 hours and $600, though I bought some items ”just in case”, and can return them.

I am a little concerned by how much apparent rust is in the well. I hope it clears up in a few days, with time to settle out. My house filter (new filter today) has probably a 1/4 inch of small metal rust flakes at the bottom.

Thanks to all for your input, this was a great learning experience for me!
 
Last edited:
One more thing: I didn't replace the control box, only the pump. I think this should be fine, since the motor specs match up from the old to the new pump. 230 volt, 3 wire, 1/2 hp. Anyone agree/disagree?
 
We still don't know what motor you pulled out or which one you put back in. That's important. If they were the same motors, then no problem.
 

Latest posts

Back
Top