supply line for sprinklers

I have a submersible with 1 1/4" poly pipe coming from it to the pressure tank in the basement. I'm planning to put an underground sprinkler system in. Today I teed into the 1 1/4" line, just before the pressure tank and ran the line outside with a valve and a proper backflow valve. I wanted to fill a 50 gallon drum and time it so I can figure what I have for GPM for the system. (I need this number to plan properly). Anyway, I tried to run the line into the barrel but my pressure switch keeps shutting off. It's one of those safety pressure switches that will cut off if the pressure drops too low. I'm wondering two things. First is it okay to tee in where I am, before the pressure tank? Second will a standard pressure switch fix my problem with the safety one shutting off?

The tee should be on the house side of the pressure tank. Otherwise the water from the tank to the tee is backwards when the pump comes on and that causes water hammer and strain on the plumbing etc..

The open pipe is too much flow and the pressure falls below the point that the switch sees as too low and it shuts off the pump. Put a valve on the pipe and have it open some when you turn the water on.

The only way to come up with your flow rate is to pull the pump up some and measure the water flow open discharge, which is what you are doing without pulling the pump some. So do this again but after moving the tee to the house side of the tank.

I figured pulling off from the 1 1/4 pipe would supply more water to the sprinklers than if I go house side where it's down to 3/4". Or will it make much difference?

murrsue said:

I figured pulling off from the 1 1/4 pipe would supply more water to the sprinklers than if I go house side where it's down to 3/4". Or will it make much difference?

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Tough call. Obviously there is measurable loss going from 1.25 to 0.75 so there is a difference. Although you do have it configured backward of what it considered normal I'd go with it until you have a reason not to. There is a risk of water hammer, but it may work fine, or not. But since you have already piped it that way I'd keep going.

Oh I should add, wait until you see the price tag for a 1.25" vacuum breaker. You may want to go with 0.75" pipe until you get past this just because of the cost.

-rick

Vaccum breaker??

How much water gpm wise are you going to need per zone?

Most tank tees are 1" but you can go up to 1.25" after the tank a foot or two and then down to 3/4".

I've got 55 sprinklers to hook up and I've got a 10 zone controller. A local contractor measured my out put on a 3/4 outside line and figured I can run 5 sprinklers per zone for sure. I plan on running a line on the surface with 6 sprinklers just to see what kind of distance I can get and experiment with some different spray tips. I'd like to run a few zones of 6 sprinklers if possible so I can get them all in.

I checked my tank tee and it's 1". I think I'll leave the tee in where it is now on the well side on the 1 1/4" and try it. The sprinklers will run at night when no other water is running in the house. If it doesn't work well enough I'll tap into the house side right at the tank tee with 1".

That's not the right way to measure your water flow etc..

Try this;
http://www.irrigationtutorials.com/sprinkler00.htm

Especially gere;
http://www.irrigationtutorials.com/sprinkler04.htm

And then here; You may want a Cycle Stop Valve.
http://www.irrigationtutorials.com/pump.htm

Gary, YOU THE MAN! Great site. Now i'm cookin with the planning of my system. Thanks.

Now I need a filter. ?source

That tutorial site is great. Tons of info. The guy suggests using a filter (150-100 micron) for the supply water to avoid problems with stuff/sand getting into the valves or heads. I'm not having any luck finding something that won't restrict my flow, preferably something with 1 1/4" ports. I'd prefer a mesh filter so it can be cleaned.