csvalves

[mouse]

Hello, need some ou your magic:
got 2 year old 1 hp jet pump and 20 gal tank from friend, want to use it for 3000 sq.ft lawn.
1. star 1 hp @ 18.5 gpm set 30-50 psi. 1.25 inlet, 1" discharge.
2. tank 20 gal with 1" opening
3. live on lake, lift from water leve to pump will be 7 foot, will push water up hill 3.5 foot.
4. got all equipment low cost from friend who was moving, including 1.25" suction hose, foot valve and 1" discharge pipe (45')
5. can I use the csv1/csv1.25 for this pump and tank, if so will you give me information on size of pipe and connections needed from pump to tank to lawn.
6. Also where to place the csv, pressure gauge and tank. maybe even an email with a diagram and a few instructions.
7. also if I really need the more expensive csv. (I am on limited/fixed income).
If you need additional information , I will be monitoring this to send it to you.

Thanks
mouse

[Cary Austin]

Hi mouse
After looking at the curve for that pump, I don't think it builds enough preesure to be able to utilize or even need a CSV.  It looks like that pump will barely be able to build the 50 PSI to shut itself off.  It will probably only be pumping 1 or 2 GPM before it gets to 50 PSI, which is as good as a CSV would do.  Your gonna have to run at 30 or 40 PSI to get any amount of flow from that pump.  But if you run only 2 or 3 GPM, and it should not be able to get to 50 to shut off.  If it shuts off while running 2 GPM, you can probably turn up the pressure switch to shut off the pump at 52 or so, and it will stay running at 2 GPM.  I would love to sell you a CSV, but you don't have enough pump to need one.

[mouse]

Hi cary
Thanks for your quick reply, even if it proves true that I don't need a csv, would you tell me how and what size pipe to use and where and how to connect the pressure regulator and tank. I don't know if I should use 1" or 3/4 " pipe. I have to run atleast 120' pipe and I only want to use garden hose to 2 sprinkler heads (maybe 3 or 4).
Thanks
mouse

[Cary Austin]

The pictures I see show that pump with a pressure switch already attached.  You just need to add a small pressure tank to a tee on the line leaving the pump.

[mouse]

cary, after taking second look at your first reply.
I lookes upperformance at star water systems and it shows the 1 hp pump has 20.5 gpm at 5 foot lift @ 40psi yet you stated that discharge at 1 to 2 gpm. I know it would lose some from friction out to 100 feet.
Could you explain you statement for me. I know next to nothing about this and relie on your expertise.
I will be trying to study up some so that I can try to post a better question.
Thanks
mouse

[Cary Austin]

Yes at 40 PSI that pump will deliver 20 GPM.  But as the pressure increases, the GPM decreases.  At 50 PSI that pump only does about 2.5 GPM.  So as long as you are using more than 2.5 GPM, it will never reach 50 PSI so the switch can shut it off.  Not shutting off is a good thing.  So you can basically vary the flow you are using from 2.5 GPM to 20 GPM, and the pump will not cycle on and off.  This is similar to what the CSV does for larger pumps.  I think that pump will deadhead or (not be pumping any water) at about 55 PSI.  That is such low pressure that if your carful with the pressure switch adjustment, you can keep it from cycling on and off at low flow.  You can’t do that with a pump that builds 75 or 150 PSI.

There are drawbacks to running a pump that close to its deadhead pressure.  If the water level drops or the pump wears just a percent or two, the pump won’t be able to reach a pressure switch setting of say 53 PSI, and it will melt down from the heat.  But you don’t have much choice with that pump unless you want to run at much lower pressure.  We can do a 35 PSI Cycle Stop Valve with a 20/40 pressure switch setting and your pump would be safe at any flow rate down to 1 GPM, but that will decrease your operating pressure to 30 to 35 PSI instead of 40.  This is because with a CSV, we don’t want to run the pressure switch as close as 1 or 2 PSI from max or shutoff pressure, which you really shouldn’t anyway, but a lot of people get away with it.

[mouse]

Hello Cary
Thanks ever so much for your reply. After reading many hundreds of questions and answers on the different forums, these two paragraphs are the most informative and instructional of them all. You have made a lot of things clear for me. I thought that at 76 year young I would have to spend some of my remaining time trying to get a pump working to water a small lawn and garden, I doubt if I will ever need 20 gpm at any time.
Thanks again
mouse