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GPM

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DogT

Active Member

1

Sunday, June 23rd 2013, 9:36am

GPM

I've got 3 pieces of information. The sheet I got with my submersible pump (3/4 hp Red Jacket 75UWL12BC) installed at 200' with a pumping level of 175' lists 1200 GPH = 20 GPM. The other I have is from an irrigation contractor, he put a meter on the outside hydrant that is directly connected inside close to the input supply/pressure tank and he gave me a reading of 12 GPM at 45 psi. I run the same faucet into a 6 gallon bucket and it takes 1 minute to fill, that's 6 GPM.

Which one do I believe or rather what do I expect to see at the 1" supply from the irrigation takoff from the 1 1/2" pipe at the well?

Does it make a difference that right at the well head where the irrigation supply is attached with what looks like 1" pvc from the 1 1/2" black plastic pipe from the well and the faucet is on a 3/4" quest pipe?

Wet_Boots

Supreme Member

Posts: 4,059

Location: Metro NYC

2

Sunday, June 23rd 2013, 11:47am

Only from a fully open pipe do you get flow and pressure readings you can trust. Forget the faucet, and work from the one-inch supply pipe.

Strictly by convention, the "12" in the pump part number indicates flow performance in the 12 gpm range. From experience, a 3/4 HP submersible in a well with the water level 180 feet deep, is more likely to give 9-10 gpm tops at useful water pressure. If the system employs an RPZ backflow preventer, the pressure being lost will only be made up by having flows reduced by a couple of gpm.

DogT

Active Member

3

Sunday, June 23rd 2013, 1:02pm

Thanks, I guess I should break out a spigot right (after or before?) the filter and install a psi meter and just measure the flow into some container. I was concerned that the booster pump might be cavitating if I have too much flow from the rotors/sprays. I reckon that would tell me if the pressure drops to 0 there while it's working? I wouldn't mind a hydrant in that garden anyhow, I could avoid running hoses across the driveway. The installers were complete idiots, I'll say it right here, Rick Carney out of Fredricksburg, VA. They couldn't even wire up the relay for the booster.

Would it be possible to install a better submersible and get rid of the booster? I think I've got 10-2 going to the pump. It's across 220V. That pump was installed in 88.

Wet_Boots

Supreme Member

Posts: 4,059

Location: Metro NYC

4

Sunday, June 23rd 2013, 2:15pm

Maybe you should fully describe what you have in place, then describe what issues you are having with the system.

DogT

Active Member

5

Sunday, June 23rd 2013, 3:14pm

Already stated submersible pump with 10" well. Well rated at 40 GPM when drilled. No city water here. 3/4 hp pump. Goes to house with 1 1/2" black plastic. Broke into 1 1/2" pipe at well head with T to feed irrigation system. Goes to check valve (probably not sufficient but they installed it without one) to filter, to booster pump and that goes to the manifold where it breaks out into 21 zones with a master shut off valve. I don't have a schematic of it, I'd like to get one. I've determined that with the booster on, I get 45psi at each zone (at a sprinkler) and about 18-20psi no booster, not enough to raise the sprinklers all the way in the largest zone. Largest zone is 9 brown VAN sprinklers, 8 at 180 deg. 1 full. Smallest zone is 4 PGP rotaries with #5 red nozzles which I plan to change to gray nozzles because of the wind here. You see 4 #6 gray nozzles in the PGP gives me about 11 GPM, which may be right at the top range I have, I need to know. The 9 brown VAN sprinklers add up to almost 12 GPM. and since I only get 6 GPM out of my faucet, I wonder....

As far as I know there are no issues, but I would like to know for sure what I have so I don't waste my time/money burning up the booster pump or buying a new submersible or if I need to. I just don't trust the contractor idiot that installed this system.

As examples of why I don't trust them, they couldn't wire up the booster (one guy connected the black and white wire together at the breaker?). Plus I have 4 40 to 50' 6' wide beds and they put mostly blue or black VAN sprinklers in those beds (it looks like they just put whatever they grabbed out of their bag, there's all kinds in different places) and I have to turn them way down to keep them from over spraying everything. And as you probably know when you turn down a 15' spray head to 6', they don't work all that great. I'm thinking about changing them all to green 8' sprinklers, green because they need a bit of lift and there are some large perennials in the beds. Plus they installed all the 4" pop ups at ground level, so I've raised them as much as I can plus put the 6" extensions on them to get them up so they don't just spray the first plant and that's it.

I tried to get the contractor to change the spray heads but they wouldn't. Everytime they came out to adjust things, they had the booster pump miswired so it didn't work, and when I got it working, everything sprayed up on the siding, patio, you get the idea.

I could go on, but it's not worth it, I just want to get it working like I want without stressing my submersible or well, even if I have to do it. At least the zone valves and controller seem to be working.

Wet_Boots

Supreme Member

Posts: 4,059

Location: Metro NYC

6

Sunday, June 23rd 2013, 5:13pm

How many acres are you watering? If the well is a no-doubt-about-it source of 40 gpm (how much doubt has something to do with your location), then the best approach might have been something other than a booster.

DogT

Active Member

7

Sunday, June 23rd 2013, 6:57pm

How many acres? That's a good question. I've been working on that. Just looking I'd say an acre and a half. But I'm going to cut out a lot of the lawn. I don't think it's necessary and I'll just water the garden beds and a small amount of lawn around the front. And I can cut out 6 zones easy. The garden beds may be 1/4 acre at most. The lawn zones are all on the PGP rotors of course and they're typically 5 rotors/zone.

The well, well it's a deep subject, but the 40 gpm is what I got from the well driller during installation and that was in 88. That said, we had a previous property that the driller said about the same with a 150' well and when we moved in, we did a load of laundry and pumped it dry. It was drilled into an underground lake and when we pumped that out, we had about 1/2 gpm or less. It took us a long time to find a guy that would set up on the same well and drill on down, but we did and we still only got 2-3 gpm, but we had 200' of head. We just couldn't water the lawn or do laundry all day long. We've never had any problems with water at this location and some days the wife does laundry all day long. Plus I've watered the yard all day long sometimes. But that's just a single oscillating sprinkler or rotary sprinkler not an irrigation system.

The current well, who knows. I suppose I'd have to get a well driller or plumber out to see what's going on or run the irrigation largest zone until it pumps mud. I wouldn't trust the contractor that did our work.

This was not my idea, the wife gets these 'hairs' and has to do things right now so we were not communicating. I would have looked into it much more, but she had the loot and just went ahead. I have no control. But now it's my problem to make it work. I'm not whining too much. Watering the gardens will be a good thing, I think she just got talked into way too much and like I say we'll just cut out most of the lawn which is the bulk of it. I can turn them into veg garden soakers or similar.

We're in the Piedmont region of VA, in the foothills of the Blue Ridge. The house and well are near the top of a hill that's 200' above a stream that runs year long into the Rapahannoc River. The house is only 200 yards from the stream, so it's pretty steep here. Our driveway is 20 deg at the steepest part.

Wet_Boots

Supreme Member

Posts: 4,059

Location: Metro NYC

8

Sunday, June 23rd 2013, 9:03pm

I think you can permanently forget the 40 gpm. What you might do as a start, to get an idea of what you're working with, is to run one of the zones you are actually happy with, and log the pressure gauge readings over a period of time. Look for the pressure to drop, and to continue dropping.


Also, you might try a zone without the booster pump, but with half or more of the (spray) heads shut off, and see if there is a better pressure picture over time.

DogT

Active Member

9

Sunday, June 23rd 2013, 9:15pm

What period of time to run the zone are you talking about, minutes, hours or days? Longest I've run a zone is 1/2 hour at once, but the controller runs things for a couple of hours each day, but at night, so I have no idea what's going on then. Log psi every 15 min with the booster/not or both? Easiest would be a lawn zone, it wouldn't bother the plants.

Wet_Boots

Supreme Member

Posts: 4,059

Location: Metro NYC

10

Sunday, June 23rd 2013, 10:14pm

Hours. The idea is to rule out a well running dry on you. When that happens, pressure drops, and performance falters.

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