Drip Irrigation Spacing

Question:
I just installed a drip irrigation system in my garden area. I have tested it several times to make sure it’s working properly before I plant my flowers. I have set the timer for 30, 45, then 60 minutes to see if I can get the right coverage. The ground gets wet at a radius of 3 to 5 inches from each hole in the tubing. This is true no matter how long I run the system. Since the holes are spaced 12” apart and it’s not reaching the full 12” in each direction, I am getting frustrated.

What can I do to improve the coverage area?

Answer:
Please don't mistake what you see at the surface for the total wetted area. It is important to remember that each emitter "hole" creates an onion shaped wetting pattern underneath it. The onions meet under the surface (of the soil) to form a uniformly irrigated area. If you took a knife or screwdriver and probed the soil halfway between the emitters he would most likely encounter wet soil just below the surface. Thus, I would guess you are getting full coverage, it just doesn’t appear that way from the surface.

Circuit Breaker Size

Question:
I am installing an irrigation lake pump at my house. It will probably be a 2 HP (Horsepower) pump. What size circuit breaker do I need?

Answer:
As usual, I can’t give an exact answer because it depends on several factors. Are you operating the Pump using 230 volts or 115 volts? What is the “service factor” on the pump motor (this will help with determine the true horsepower of the pump)? How sensitive of a breaker is being used? Etc.

However, I have a general guideline to follow. Read the Full Load Amps (FLA) on the pump motor plate. Most contractors install twice the FLA. Thus, if the pump draws 15 full load amps, the circuit breaker should be 30 Amps. Also, never go larger than three times the FLA. Thus the MAXIMUM size would be 45 amps.

Here is a general guideline of Full Load Amps (based upon 230 volts):

1/2 horsepower pump draws roughly 5 Amps (15 Amp breaker)
3/4 horsepower pump draws roughly 7 Amps (15 Amp breaker)
1 horsepower pump draws roughly 8 Amps (15 Amp breaker)
1 1/2 horsepower pump draws roughly 10 Amps (20 Amp breaker)
2 horsepower pump draws roughly 12 Amps (25 Amp breaker)

Please Note:
This is based upon 230-volts at the motor. 115-volts will double the Amperage draw.
Always read the motor FLA on the pump motor itself. This is a much more accurate number. Lastly, always have a licensed and qualified electrician do the installation according to your local codes and ordinances.

Sloping Drainage Pipe

Question:
I am installing some drainage pipe at my house. The manufacture states to install the pipe on a 2% slope towards the outlet (or away from the house). How do I know if I have a 2% slope?

Answer:
How do we check to see if we have a 2% slope? One option is to take a level and tape it to a perfectly straight 10’ board. Place one end of the board on the ground (near the top of the slope), take the other end and raise it off the ground (near the bottom of the slope) until the board (& level) is perfectly level. Now measure the distance between the board and the ground at the bottom of slope. It should be 2.4” drop. (10'x 12" = 120" x 2% = 2.4") Thus, we have a 2% slope.

18-Gauge Wire & Valve Operation

I am using Multi-Strand wire on a residential installation. The thickness of the wire is
“18- gauge”. How far can I run this wire to operate my valves?

Answer:
The distance depends on a lot of issues......

The voltage coming out of the transformer, 24 or 26 volts?
The size of the transformer or how many amps is the output?
How many valves are you operating at one time?
How many amps or watts does your solenoid draw? Type of solenoid?
How much water pressure is at the solenoid?
How good are the wire splices?
Etc.

These are all considerations that need to be taken into account when sizing valve wires. However, if you want a simple down-n-dirty answer, use this guideline.

18 Gauge is good for 1000 feet, if you are operating one valve at a time.
For two valves operating at a time, cut this number in half.
For three valves operating at a time, cut this number in thirds.
Etc.

Pleaae note: This is for new installations only with new solenoids.

Zone Won't Turn Off

I have a situation where one of my irrigation zones won't turn off (even when I unplug the controller and take the batteries out of it). The only way I could get the water to shut off is to turn it off at the main water supply. Any help?

Also, I noticed that the valve box is filling with water. Is that normal?

Answer:
First, yes its normal for a valve box to fill with water, (unless you have a good draining soil like sand). Usually, a small drip will fill the valve box or rainwater will collect inside of it, thus filling it. I usually recommend having 12” of gravel underneath the valve box to drain any collecting water.

Since you unplugged the controller and the valve is still operating, that tells me that it’s not an electrical problem; it must be a hydraulic problem.

First check the obvious. There is a "manual bleed screw" on top of the valve. This might have come loose, thus keeping the valve operating and the valve box flooded. However if you did check this and its not the problem, than the valve has to be stuck in the open position, or the solenoid (on top of the valve) is not seating properly, thus keeping the valve on.

You essentially have to take apart the valve and remove the internal components. Wash them down with a hose and reassemble them. Visually check the diaphragm for small tears. Also, I would replace the solenoid with a new solenoid to make sure it seating properly. It has to be one (or both) of those problems. Lastly, check to see if the body of the valve is cracked, this would keep the zone operating too.

It might be cheaper to buy a whole new valve and swap the components. You can purchase at your nearest John Deere Landscapes store at 1-800-347-4272. A new 1" residential valve should cost roughly $20.

Pond Water Volume

How do I calculate how much water is in my pond?
I am adding a water treatment to my pond and I need to know how many gallons of water is inside of it.

Answer:

First figure how many cubic feet are in the pond.
This is calculated by taking the average width x average depth x average length.

Thus, if your pond is roughly 10’ wide by 3’ deep by 10’ long,
our answer would be 10 x 3 x 10= 300 cubic feet.

Now, we have to convert to gallons.
There are 7.481 gallons in a cubic foot. Thus, 300 x 7.481=2,244 gallons of water.

Best Time of Day to Irrigate

What is the best time of day to irrigate and for how long? I have rotary sprinklers for the grassy areas and small misters for the shrub areas. Someone told me that misters put out so much water that you do not run them as long as the large rotary sprinklers.

Answer:
I cannot give you an exact time in minutes to water, but here are some very general guidelines.

1. Irrigate early in the morning. Your "evaporation rate" is much lower compared to the hot mid-day sun, thus saving water. Don't irrigate at night, this promotes various turf diseases. Diseases love cool nighttime temperatures.

2. Misters (actually called Spray heads) do apply more water then rotors. Rotors generally apply 1/3" of an inch of water per hour compared to Misters applying about 1-1/2" of water per hour. Thus a 1 to 5 ratio (Misters versus Rotors) in "run-time" is a very general rule.

3. Grassy areas need more water than your shrubs.

4. Here is a link that might help in your research. www.Irrigation.org.
There is a lot of additional links on their website.