Planning my first irrigation system

[villnorm]

Hello everyone,

I'm living in Montréal and I'm currently doing my first irrigation system for my new home. I started doing my homework of planning my system by looking at the available water source for the house. I have read many websites to try to get an idea of the best setup for my house, but I would like your advises.

Here's the specs:

Water is provided by the city and it enters directly in the basement from a copper pipe to the main shutoff valve (no water meter in my town), then it get transfered into a 3/4" Pex pipe to the rest of the house. There's a hose faucet outside the house on a 1/2 Pex pipe. I did the GPM test on it and got around 6-7GPM. I don't have a PSI gauge to plug on the faucet, but the house have a water softener on the main 3/4 Pex pipe and has 2 PSI gauge on it (One showing the around 60PSI from the main 3/4 Pipe and the other after the softener process going to the rest of the house is showing around 57PSI).

• My first question, I find that the 6-7GPM out of the 1/2 faucet seems low. If I plan to connect my setup directly to the 3/4in main water Pex pipe before the water softener would this improve the GPM significantly?
  
  
• I live where we have freezing winters (-22F/-30C) so I came to the conclusion that a Pressure vacuum breakers (PVB) wouldn't work outside unless I remove it for winter. I'm thinking instead to use a double check valve assembly (DCA) or a reduced pressure zone device (RZPD) if the pressure loss is acceptable, that would be installed in my heated basement (so it won't freeze). I would still drain the whole system every winter. Is that a good idea?
  
  
• I read about the water velocity and that the best to avoid problems is to stay below the 5 feet per minute range. Would it be ok to connect a 1" pex pipe to the 3/4 main water pipe (after the main shutoff valve) using a Tee for my system? I'm wondering if the velocity inside the main 3/4 pex (before going into the 1" pex) would be an issue in that case or is this 5 fpm thing only applicable downstream of the system to protect the sprinklers/valves?
  
  
• Do I need a pressure regulator on the system or is the sprinklers already able to regulate the pressure themselves?

Thanks for your time!

 

[breplum]

You need to know what your pressure is.
Some utility companies know what the neighborhood pressure is. Best is to buy or borrow a pressure gauge that screws on to a hose bibb.
Depending on exactly what and how you want to irrigate pertains as to whether 3/4" PEX is ideal vs the upsizing to 1".
The I.D. of PEX tube is slightly reduced, crimp fittings even more reduction, but it depends on how far you are pushing the limits of each sprinkler zone.

 

[villnorm]

You need to know what your pressure is.

I have 60PSI from the main ¾ pex pipe.

 

[Mitchell-DIY-Guy]

Why struggle to "re-invent the wheel" as they say?

https://store.rainbird.com/learn/design-service
Rainbird (like them or not) is one of the leading suppliers of in-ground irrigation systems and parts. Go to their link, supply them with some details on your project, and they'll design the system for you at no charge. You can then build it yourself or find a contractor to do it for you. Are you biased against RainBird for some reason? The design can use other parts too.

Still want to get your hands dirty so to speak? Well, then use the guidebook from Hunter, another well known and respected supplier:

https://www.hunterindustries.com/residential-system-design-guide
This is a no-brainer!

 

[wpns]

Nothing wrong with 6-7 GPM, you can design a system that uses 2GPM if that's what you've got.

How does the pressure in the house drop if you open the hose spigot all the way?

 

[Twowaxhack]

Low volume means more zone valves.

You could just use one zone valve per head.

 

[havasu]

Most residential areas where I live have 6 station zones. 3 for the front and 3 for the back. Divide your needs by the gallons needed per hour, and you can always adjust the time to increase gallons. I use Rain Bird water saver RVAN rotating sprinkler heads, so I have virtually no water loss onto my sidewalks. They made me run for a longer time to provide the necessary water, but they cover real well. All my planters use small 1/4" drip lines, so I don;t waste any water wetting the dirt around the trees. Lastly, I installed a Rachio sprinkler controller which is WI-Fi operated, and I can use my phone to adjust for extreme weather, and the system uses local weather readings to adjust for humidity or shut off during rain events.

 

[villnorm]

Thanks guys! Yes I plan to use the rainbird design service but my questions right now are more related to the water supply setup which rainbird doesn’t offer any advise on.

One big question I would need to answer before I start is if I should plug a Tee in my main supply (on the ¾ pex) to supply my setup or if the hose using ½ would give the same gpm?

I would like to think there would be a improvement in gpm by using the ¾ supply insted of the ½ hose one but how much that improvement would be is still a mystery to me.

 

[Twowaxhack]

3/4” would be much better than 1/2”.

Don’t use 1/2”.

How much better ? Cut the 1/2” tee in first and get your stop watch out. Then remove the 1/2” and install the 3/4”. Again, get your stop watch out.

 

[havasu]

.... and if you home has a pressure regulator installed, start the sprinkler build before the regulator. This is how I started my front irrigation lines.

 

[Mitchell-DIY-Guy]

In Michigan our water came in from a 1" copper main, but went to ¾ at the meter in the home. First tee after the meter took it back outside to the vacuum breaker.
Yes every autumn the system needed to be blown out and the valves opened on the vacuum breaker to prevent freeze damage. It was routinely done for $40 by roving gangs of guys with compressors. Every weekend day in October and November they'd be cruising around...