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Better pump pressure with more zones on than with only one zone on

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Norm

New Member

Posts: 4

Location: West Michigan

1

Tuesday, April 12th 2011, 9:59pm

Better pump pressure with more zones on than with only one zone on

I have a 2 hp Wayne WLS200 pump. If I open more than one zone I get 40 psi and plenty of volume. If I only have one zone open with 6 sprinklers, my pressure will start surging from 20 to 40 psi and eventually drop to less than 20 psi and volume will drop. If I open another zone in addition so there are 12 or more sprinklers the pressure and volume will return to normal. It did not do this in the past. I have disassembled the pump and inspected the impeller, diffuser, and all seals. They appear to be ok. I cleaned and reassembled the pump, checked and resealed the inlet from the check valve to the pump. It appears to me that the pump works ok when there is no resistance to flow, but as soon as resistance increases the pump starts cavitating or something and it quits pumping. I have a 3/4" valve that I can open on the main outlet before any zone valves that I use when priming. If I leave that open all the time the zones all work fine with 40 psi and great volume, but it wastes lots of water and makes a HUGE flood around the pump ;( (it will spray a 3/4" stream of water quite a distance and still run the zone at 40 psi. I need to be able to run single zones without my volume and pressure dropping off. Any ideas out there? ?( Thanks.

Wet_Boots

Supreme Member

Posts: 3,596

Location: Metro NYC

2

Wednesday, April 13th 2011, 7:47am

You installed a pump that can probably move over 60 gpm, to run 6 heads at a time? This is not a good match. Absent replacing the pump with a better one, your best bet is to re-nozzle each head to increase their flow.

Norm

New Member

Posts: 4

Location: West Michigan

3

Wednesday, April 13th 2011, 9:34pm

Thank you for your reply Wet Boots. The pump has been in use for several years with no problems and suddenly developed this anomoly. I use the large nozzles in my sprinkler heads. Why would it do this now when never done before?

Mitchgo

Supreme Member

Posts: 502

Location: Seattle

4

Thursday, April 14th 2011, 12:11am

Sounds to me like you have air in the pump still. I've dealt with your exact situation several times now and it's always ended up being the fittings on the inlet pump side leaking ( So the pump sucks in air)

I've been told to do this by a couple pump experts now, and so far it's been very successful . Re-do all the inlet and outlet fittings for the pump, since its plastic going into metal- be sure to use teflon and paste . On the Outlet side of the pump install a single way in line check ( use brass) . This serves 2 purposes- to relieve all the extra back pressure on the pump itself and to give the ability to install a bleeder. So between the Pump and the Check valve Install a tee ( For sake of argument call it 1.5" piping) So a 1.5soc x .5 thread x 1.5 soc ( normally called a sprinkler tee) , Then install a .5 " plastic ball valve, then after install a .5 x .25 drip barbed adapter, run drip line a little bit away from the pump, leave the ball valve 1/4 to 1/2 way on.

Basically by doing this, it really helps get the air out of the pump, you don't loose prime because it's after the pump and you also don't loose the water in the main line because of the check


It's possible to have a leak somewhere else in the inlet line leading from the foot valve too.

Norm

New Member

Posts: 4

Location: West Michigan

5

Thursday, April 14th 2011, 6:51am

Thanks Mitchgo. I was wondering about pulling air... the sound of the pump cavitating sounded like it. I had already resealed everything between the check valve and the pump, which didn't help. I didn't do anything ahead of the check valve because I wasn't losing prime, so I figured it was ok... maybe.



I think I might go back and re-check for leaks again though. You recommend using teflon tape AND paste on the fittings?? I haven't tried that.



With the bleeder... do you leave it on all the time, pump running or not running? I was kind of hoping to get away from wasting the extra water. I've been contemplating running two zones at once to relieve backpressure, but it used to work before so I figure something must be wrong and I don't want to just cover up the problem.



Thanks for the replies guys... I'm gonna try to get some time this weekend to tear into it again. I will let you know what happens. :)

Mitchgo

Supreme Member

Posts: 502

Location: Seattle

6

Thursday, April 14th 2011, 10:18am

Yeah the paste on metal fittings really help

With the drip line and ball valve turned on , you only loose a gallon every 15 min of run time or so? not bad at all . Yes you would leave it on always

Norm

New Member

Posts: 4

Location: West Michigan

7

Thursday, April 21st 2011, 9:03pm

Thank you so much for the help. :) I disassembled all the inlet and outlet fittings and re-did them with teflon tape and paste and fired her up. Working GREAT now :D ... 42 psi and major volume even with only one zone on. No pump cavitation... it sounds great.

I didn't install the check valve and drip line. I thought I would try this first since the pump worked fine before. If I have future problems, I will install them.

I guess I never thought sucking air would let me have better performance with everything "wide open" than with things "closed down" some. I learned something new today. :rolleyes:

Thank you again... you are a lifesaver. :thumbsup:

Mitchgo

Supreme Member

Posts: 502

Location: Seattle

8

Thursday, April 21st 2011, 11:59pm

Glad to hear it worked :)

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