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secutanudu 06-30-2010 02:11 PM

Planning my lawn sprinkler system
I am going to install a lawn sprinkler. I have a 3/4" feed from the street with 3/4" new threaded ball valves on either side. Immediately downstream of the house-side shutoff, the pipe is dropped to 1/2" for the whole house. I have about 75-80 PSI on my current hose spigot.

My thoughts were to get a 1 x1x1/2 tee. Feed the tee with a 3/4" threaded x 1" sweat adapter. The half inch would feed the house, the other 1" would feed the sprinkler. This sound ok?

Once I branch off for my sprinklers, i plan to install, in this order:

meter...Tee (1" side)...shutoff valve...double-check valve...boiler drain...exit house....boiler drain#2....sprinkler manifold.

Any issues with this plan?

Also, is there any reason to continue with 3/4" pipe for a while before converting to 1/2" for the house water?


Alan 06-30-2010 09:00 PM

As for running with 3/4 for a ways...

here's the big question : How many bath is your house? Kitchen? Laundry? Utility? Any other fixtures tapped into the water system?

Have you been underneath to look at the incoming water line? Is it 'bushed back up' to a larger size under the house?

If you're going to have your yard dug up anyway, it may be worth your while to upsize the main feed up to the house or as near as you can get it. a 1/2" line doesn't do much in regards to GPM of water.

secutanudu 06-30-2010 09:04 PM

The incoming feed to the house, at least coming into the meter in the basement, is 3/4" It's dropped down to 1/2" right after the meter.

Alan 06-30-2010 09:10 PM

Oh I see. Meter in basement :D

We don't have basements here. Disregard on the digging a new service then. :D

When we plumb houses out here, we generally run 3/4" far enough so that at least the shower and toilet are pulling a dedicated 1/2" line off of the 3/4" line.

If you aren't noticing any issues with water flow rate when you're using multiple fixtures in your house at once, I'd leave it alone unless either a : You're bored and want to repipe the main feed under your house, or b : just feel like wasting some money or C : if the copper is really really old and needs replacing anyway.

secutanudu 06-30-2010 09:12 PM

How does the rest of my plan sound? Is it ok to go from the 3/4" feed, to a 1" tee, then back down to 1/2" for the house?

Alan 06-30-2010 09:17 PM

Is your 1" piping for the sprinkler system going to be maxed out? I'd be a little worried that when the sprinkler system is going and if it's utilizing that entire 1" line that the rest of the house will have little to no pressure.

The only thing that you could possibly do if the pressure isn't too terribly high is to tap in before the pressure regulator if you have one, so that your sprinkler is operating off of the high pressure, and still leaving (hopefully) plenty of water and pressure available for your house.

Hopefully someone else will verify my theory. :thumbup:

secutanudu 06-30-2010 09:34 PM

Well, I don't have a regulator. I have 80 psi coming into the house, but that's at the spigot which is on 1/2". I assume if i increase from 3/4" to 1" i will lose some pressure? How much? I'm not too worried about pressure loss when the system is runing. It'll be running on a timer early morning before people get up, and only for like 30 minutes 3 times a week.

Alan 06-30-2010 10:10 PM

Hard to say exactly how much... there may be someone around here who knows if and how you can calculate it. My knowledge is not that extensive at this point, sorry.

secutanudu 06-30-2010 10:12 PM

Well I already bought 100' of poly pipe for the I guess I'll find out :)

What type of copper is appropriate for this? L or M? I assume L?

secutanudu 06-30-2010 10:32 PM

1 Attachment(s)
Here's a sketch of what I plan to do...easier to see in graphical form...

Alan 07-01-2010 12:03 AM

Looks real simple as far as putting it together, but the issues I mentioned before still stand.

secutanudu 07-01-2010 06:47 AM

Which issue? Losing pressure in the house while the system is running is the only one you mentioned, right? If so - I'm not too concerned. Also, my yard isn't that big, so it won't be THAT much water being used for the sprinklers.

Thoughts on M or L pipe?

The Engineer 07-01-2010 07:33 AM

What you want to do is fine, you won't loose any pressure going with a larger pipe size.

Are you on a city sewer as well? If so, my only recommendation is to contact your town water/sewer department and see if they have any guidelines about irrigation systems. It might be good for you to put a sub-meter on the irrigation line (after the double check) so you don't get charged sewer fee's on the water your putting on the landscape since that water is not going down the drain.

secutanudu 07-01-2010 07:47 AM

I have looked at the town code for guidelines. The only thing i saw was what type of backflow device was allowed and which days I could water. It actually restricts automatic sprinling from 1:00AM -4:00 AM - that seems awfully early...I was planning on doing it around 5:00-5:30.

Alan 07-01-2010 08:54 AM


Originally Posted by The Engineer (Post 463882)
you won't loose any pressure going with a larger pipe size.

Really? :eek::eek::eek:

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