Just completed my new yard under ground irrigation system. All is well
except for two things.
The 6 valve manifold that I laboriously built out of 1 1/2" galv. pipe leaks at almost every joint. The joint compound apparently wasn't enough to do the
job. I see from other forums that some "plumbers" would use teflon tape plus joint compound on someting like this. My hope is to redo this thing only once.
The system uses a 3 HP pump pushing lake water at 50+ psi. I'm still hooking up controls so that is still theoretical.
This is my first post to this DIY forum. I am a do it yourselfer on all kinds of my own home and yard projects so will have a variety of questions in the future . Happy to find this form.
Why did you choose galvanized pipe? Is the manifold to remain above ground?
If I were doing it all over again, I'd use Sch 40 PVC with Sch 80 fittings, and place the whole manifold in one or two valve boxes in gravel below grade. Save the galvanized for the above-ground stuff. At least if it leaks (it won't with PVC), you've got it draining into gravel.
Also, depending on what kind of sprayheads you're using, you might want to add a pressure reducer. Rotors for mid-size throws (+/- 35 ft radius) are made to operate at 50 psi, but smaller pop-ups run ideally at 30-35 psi.
Although, I assume that since you have a lake your yard is fairly large?
Your choice of sprayheads might be limited by your flow rate, though. What is your GPM from the pump? I would guess it's adequate if you're getting 50 psi thru a 1-1/2" pipe.
BTW, Congratulations - no more walking around with hoses!