Help with low GPM(Greenhouse)

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thegeeps20

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Hi all..first post. I run a greenhouse business and would like some input on an ongoing problem with low GPM from my submersible pump.
Background:
-artesian Well is 180', pump about 160'(produced 10GMP when dug 20 years ago, refrac about 6 years ago, don't know the GPM.
-high Iron! Lots of rust.
-Goulds 1/2 HP 10GPM, 230v pump
-I've never run out of water, even when running 5-6 hours straight(see below)
-depth to water in well when pump not running..a guess would be 50'
-pump not short cycling at all
-voltage reads 220 at pressure switch.


-Piping runs about 6' underground from pitless adapter into a "pit"(where there is a faucet to drain during winter), From there another 5-6' to a Weltrol tank inside a greenhouse.

- the well pump pumps to the Welltrol tank then about 15' of 3/4 hose from the welltrol tank to fill a 1,500 gallon holding tank.

-I irrigate using a booster pump that pulls water from the 1,500 holding tank. I water 5-6 hours straight most days in April-June. So, the submersible pump is running constantly filling the 1,500 holding tank as I irrigate. I then have it fill again on a timer overnight.

-Booster pump is pushing water at about 10GPM

-3 years ago put new pump in well, was getting 7.5GMP from Weltrol to storage tank.

-Last spring I measured my output from weltrol tank into the holding tank..only 4GMP. I pulled pump and intake was pretty caked with rust, cleaned out and replaced piping and wire in well.(rust build up inside of old pipe) and GPM increased to 6

-this spring output was back to 4GPM. I pulled pump and intake didn't look that bad, decided to replace pump again with brand new Gould's 1/2HP, 10GPM..exact same pump I put in 3 years ago that immediately gave me 7.5GPM. This time though, only up to 6 GPM. Very disappointing, thought for sure I would be back to 7.5 with new pump.

-So..I would like some input on what might be happening. I'm not sure the well pump is adequate. I tried to understand the charting, but got confused on the PSI part and what I needed. Goulds chart shows depth to water up top and PSI(0-60) on the left to determine the GPM. What would be the PSI in my situation? My pressure switch is 40/60, but isn't that irrelevant as the Weltrol tank runs out in a few minutes as the holding tank is filling. The faucet is wide open and the well pump is running constantly from this point on for 5-6 hours to fill the holding tank.

- I should note that when the pressure gauge hits the kick in of 40 PSI, I hear the click and the gauge immediately drops below 10PSI. I believe this has ALWAYS happened from day one. Weltrol tank bladder seems fine, holding air pressure(about35) below cut in pressure. The faucet is wide open from Weltrol tank with 3/4" pipe about 15' long straight into the 1,500 holding tank. No short cycling of the pump.

- I'm thinking 3 thoughts....1)I need to match the well pump better..maybe 3/4 HP? 2)the piping from the pitless adapter to the side "pit", then up to the Weltrol tank could be caked with rust and slowly building up over the years. Again, I replaced the 160' feet of piping to the pump to pitless only.
3)the well is not producing what it used to causing the water level to be lower in the well meaning well pump would produce less GPM than in the past. However, even running 6-7 hours straight, I've never run out of water...so this seems unlikely.

-sorry for the long post, just wanted to give all issues I can think of. Bottom line, I need the well pump to be able to fill the holding tank at around 6-7GPM so when I'm watering from the booster pump(10 GPM), the holding tank doesn't run out too fast.

-Key fact-3 years ago, new well pump pumping 7.5GPM into holding tank via Weltrol. This year, replaced with brand new exact same model and only getting 6GPM. This after replacing new piping in well last year.

any input would be much appreciated.
 
Something is not right. If your water level is anywhere close to 50', when the pump starts at 40 PSI, that pump is producing 12 GPM and should quickly fill the tank to 60 PSI and be shut off. As the water level in the well is pulled down from 50', the pump will produce less water. But it will still produce 7.5 GPM at 10 PSI from a depth of 170', and the pump is only set at 160'.

My guess is that you have a restriction in the line between the pump and pressure tank. I would cut the pipe at the well and do a flow test. It may even be the tank cross is clogged and causing the restriction.
 
I agree, cut the pipe at the well. Do a bucket test with a 5 gallon bucket after running the pump long enough for it to produce a steady stream. This is the actual GPM the well can produce. Unless the water in the well is dropped to the pumps inlet at which time it will stop pumping for a short while. Take the Well X tank out of the equation. It has nothing to do with the pump or the well.
 
Does it make sense for the gauge to drop from 40 PSI to less than 10 PSI instantly when the pump kicks on? The water is coming out at full pressure from the tank from 60PSI until the pump cuts in at 40PSI, then a big drop off.
Also..What PSI do you think I'm using in my set up? This number is needed for pump sizing in the performance charts.

Is the tank cross the inlet or the outlet?
 
The tank crosse is both the in and the outlet. The reason the tank goes from 40 to 10 is because the tank has nothing to do with what the pump is doing. The pump cannot put out enough volume to pressure up the tank so the pressure drops off.
 
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Update..you guys got me thinking, and I don't know why I didn't think of this before...The side pit has a faucet that I use to drain the pipe up to the Weltrol tank during winter. I attached a 50' hose from this faucet in the pit, thus bypassing the piping leading from the pit to the Weltrol tank. The result was 8GPM..2 GPM more!!

So, it appears the pipe from the pit to the tank must be restricted with rust build up and probably also the pipe from the pitless adapter to the faucet in the pit..so probably when clean, I should be getting even more than 8GPM.

I've attached a pic of my set up in the greenhouse. The tank can't be the problem because the water up from the well would go straight out of the faucets and not even enter the tank when the pump kicks on and the Weltrol is empty. Is that correct? I should also make sure the faucets themselves aren't caked with rust.

Lastly, is there a snake tool that would run something just a bit smaller than the diameter of the piping to clean out the rust? My local plumber just used a wire last year when I asked if he could snake out the piping.. which was basically useless. I'm thinking cut the pipe in the pit and run some kind of powerized snake that would clean out the piping in the pit to the pitless adapter and the piping leading up to the Weltrol tank. Is this possible?
Would sure beat digging everything up.

Edit..looking at the pic below..would I be getting lower GPM out of the hose(that hose feeds my storage tank) because water pushed up from the well is flowing out the faucet, but also a portion going into the Weltrol tank?

IMG_1280.JPG
 
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Can you not get 8 GPM from that faucet in the picture to the left with the hose attached? I also only see one line coming to the tank? Where is the line going to the house?
 
Valveman said:
Can you not get 8 GPM from that faucet in the picture to the left with the hose attached? I also only see one line coming to the tank? Where is the line going to the house?
Click to expand...

No, only 6 GPM from that faucet. Only one line to tank..that faucet on the left feeds my 1,500 Gallon holding tank. Not sure what you mean by line to house. This is at my greenhouse business.
Talked to my plumber today..he wants to see what the GPM is right at the pitless.(as you guys said) He says it should be 10+GPM. If so, then there must be a restriction on piping from there to Weltrol obviously. He suggested running piping above ground to bypass the restricted piping and somehow be able to drain in winter by the faucet in the pit.
Does this sound like a good plan? If I'm getting 10 GPM at the pitless, with my current set up, would I lose any GPM if the piping was not restricted?...meaning would I lose any volume with water going out of that faucet on the left and water also going into the Weltrol tank?....or would no water be entering the Weltrol with the faucet wide open?
 
If you can get 10 gallons per minute at the pitless, you can get 10 gpm anywhere you like if the pipes are large enough to prevent friction loss. 1/2" and 3/4" hose bibbs are not ideal for this setup.
 
I agree but if the hose bibb was the restriction there would still be a lot of pressure on that gauge. The restriction has to be on the white pipe coming in somewhere.
 
with faucet wide open, would some water being pumped up from the well still flow into the Weltrol tank? If so, how much would that effect my GPM going through the faucet into the holding tank?
 
You should have about 38 PSI air charge in that tank. So it will not accept a drop of water until the pressure increases above 38 PSI. The tank has nothing to do with the problem.
 
You should have about 38 PSI air charge in that tank. So it will not accept a drop of water until the pressure increases above 38 PSI. The tank has nothing to do with the problem
Click to expand...
Or the solution!
 
problem solved..as you guys suspected, piping from well to pit and pit up to Weltrol was caked with rust. My plumber bypassed and ran piping above ground, now getting 15GPM to my holding tank with PSI about 25! Now I have to be careful I don't out-pump the well.

pipe.JPG
 
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