8.4 Spring Startup & Seasonal Commissioning

8.4 Spring Startup & Seasonal Commissioning

Quick Answer: Open the water slowly. Charging an empty mainline through a fully opened isolation valve sends a high-velocity water column slamming into the first closed valve or dead end, generating a surge spike that ruptures fittings, cracks the backflow assembly, and blows diaphragms. Fill the assembly first, then crack the downstream shutoff a quarter turn at a time, purge air through the lowest zone, and only then bring the system to full pressure.

Section 8.3 covered winterization. The CIT blueprint pairs the two — J. Startup and Winterization Procedures — and startup is where more damage happens, because a system that survived winter perfectly can be destroyed in the first ten seconds of spring pressurization.

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1. Before Any Water Moves: The Pre-Charge Inspection

Walk the site with the water still off:

1. Backflow assembly. Look for cracked brass or bronze bodies, split bonnets, a bulged or missing relief-valve cover, and bent or broken test cocks. Freeze damage in a backflow body is the most expensive single failure a technician will find at startup. Confirm both shutoffs are closed and both test cocks are ready to open.
2. Valve boxes. Remove lids; clear soil, ice, and rodent nests; look for cracked bonnets and split solenoid bodies.
3. Exposed piping and poly tubing. Split PVC risers, fractured funny pipe, and cracked drip tubing.
4. Heads. Heads heaved by frost, tilted, buried under thatch, sunken below grade, or physically broken off.
5. Controller and power. Confirm 120 VAC at the receptacle, the display is live, and the date and time are correct. Confirm any rain, freeze, or soil-moisture sensor is not in a bypassed or tripped state.
6. Drains. Close every manual drain valve that was left open for winter. A manual drain left open will not self-seal and will dump water into the trench the moment the system is charged.

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2. The Slow-Fill Pressurization Sequence

An empty 2-inch mainline holds a lot of air. When water rushes in behind that air, the column accelerates unopposed until it hits the first restriction — and then all of its momentum converts into pressure in a fraction of a second.

Sequence:

1. Confirm the controller is OFF so no zone valve opens mid-fill.
2. Confirm both backflow shutoffs are closed.
3. Open the test cocks on the backflow assembly to give trapped air an escape path.
4. Slowly open the upstream (No. 1) shutoff — a fraction of a turn at a time — and let the assembly fill. Listen: the hiss of moving water should fade as the body fills.
5. Close the test cocks once water, not air, appears.
6. Slowly open the downstream (No. 2) shutoff, roughly a quarter turn, and let the mainline fill. Depending on mainline size this can take several minutes — that is normal and correct. Only when the sound of flow stops should the shutoff be opened fully.
7. Walk the mainline route and check for surfacing water before energizing any zone.

Exam-ready rule: the correct startup answer is always the slower one. "Open the main valve fully to charge the system quickly" is never correct.

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3. Purging Air and Commissioning Zone by Zone

Start with the zone closest to and lowest in elevation from the point of connection. Air pushed ahead of the fill has to leave somewhere, and the first zone run is the exhaust.

For each zone, in order:

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4. Controller Reprogramming and Sensor Verification

Startup is not complete when water flows — it is complete when the schedule is correct:

• Set the current date and time, including daylight saving.
• Restore or rebuild start times, run times, and watering days for each program, grouping by hydrozone.
• Set seasonal adjust to the current spring percentage rather than the peak-summer value; spring ET is a fraction of July ET.
• Program cycle-and-soak where precipitation rate exceeds soil intake rate (Section 6.3).
• Confirm the rain, freeze, and soil-moisture sensors are active, not bypassed, and test each one — jump the sensor terminals or trip the sensor and confirm the controller responds.
• Verify each station individually from the controller so that a mis-wired station is caught now, not in August.

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5. Closing Out the Startup

1. Schedule the backflow test. Most jurisdictions require an annual certified test of testable assemblies (PVB, DCVA, RP) by a licensed tester, and spring startup is the standard time to do it.
2. Document repairs and update the as-built with any changed valve or head locations (Section 1.3).
3. Leave the customer a record: zone map, program schedule, sensor settings, and repairs performed.
4. Set the controller to run, and confirm the first scheduled cycle executes as expected.

Timing note: wait until the danger of a hard freeze has passed. Charging a system ahead of a late freeze re-fills the very components that were drained to protect them.