Adding a new sprinkler head requires integrating a connection point directly into the existing PVC mainline pipe. This modification is common for property owners optimizing their landscape watering. The process requires careful planning and precise chemical bonding to maintain the system’s integrity under pressure. This guide outlines a step-by-step method for successfully incorporating a new head into your current layout.
Necessary Supplies and Preparation
The project begins with gathering specific materials designed for PVC pressurized water lines. A specialized PVC pipe cutter ensures a clean, square cut, which is necessary for a strong seal. The most important components are a T-fitting, a riser or swing joint, and the new sprinkler head, all of which must match the existing PVC pipe’s diameter and Schedule.
The Schedule designation refers to the pipe’s wall thickness and pressure rating, with Schedule 40 being the common standard for residential systems. Mixing schedules can compromise the system’s strength and the longevity of the connection. Chemical preparation is achieved using PVC primer, which cleans the pipe surface and softens the plastic, preparing it for the solvent cement.
The solvent cement chemically welds the pieces together into a single, fused unit. Selecting a medium-set formula provides extra working time compared to quick-set options, which is helpful for beginners. You will also need a measuring tape, clean rags for cleanup, and a shovel to access the existing line before modifications begin.
Isolating the Line and Making the Cut
Before modification, completely shut off the water supply to the irrigation zone at the main control valve. This prevents flooding while the system is open. After isolating the supply, activate the zone briefly to drain residual water trapped within the line, reducing hydrostatic pressure to zero.
The next step involves carefully excavating the area to expose the mainline pipe where the new T-fitting will be placed. Once the pipe is accessible, use a measuring tape to mark the exact location where the section needs to be removed. The length of the removed segment must precisely match the length of the new T-fitting, accounting for the depth of its two socket ends.
Using the specialized PVC cutter, a clean, perpendicular cut must be made at both marked locations. A ragged or angled cut introduces air gaps and stress points that will compromise the future solvent weld. Removing the exact amount of pipe ensures the mainline remains straight and properly aligned when the new fitting is introduced.
Assembling and Gluing the New Connection
The bonding process requires that the pipe and fitting surfaces be clean and dry immediately after cutting. Primer is applied liberally to the exterior of the pipe ends and the interior of the T-fitting sockets using the applicator brush. This solution prepares the PVC by slightly dissolving the plastic surface, allowing the cement to achieve complete molecular fusion.
The solvent cement is applied over the primed surfaces, often using a slightly heavier coating on the pipe end compared to the fitting socket. The application must be swift and uniform, ensuring the entire surface area that will be joined is covered.
The T-fitting is then immediately pushed onto the pipe end, simultaneously rotating it about a quarter turn as it is inserted fully into the socket. The rotation helps distribute the cement evenly and ensures a strong, continuous weld around the entire circumference. This connection must be held firmly in place for at least 30 seconds to prevent the natural forces of the pressurized water line from pushing the fitting back out of the socket.
Repeat this priming, cementing, insertion, and holding process for the second side of the T-fitting onto the remaining mainline pipe section. Once the T-fitting is permanently installed, the riser or swing joint is threaded into the remaining open socket. This vertical pipe section allows for height adjustment and connects the mainline to the sprinkler head.
The chosen sprinkler head is attached to the top of the riser. The newly welded joint requires time to cure, allowing the solvents to evaporate and the PVC plastic to fully harden. Manufacturers recommend waiting a minimum of two hours before reintroducing water, though waiting 24 hours ensures maximum joint strength.
Final Checks and System Activation
Once the specified curing time has elapsed, the system can be slowly repressurized by gradually opening the main water supply valve. A slow introduction of water prevents a sudden pressure surge that could potentially stress the new, still-curing joints. The entire connection, including the T-fitting and the threaded riser connection, must be immediately inspected for any signs of weeping or dripping leaks under pressure.
Before installing the final sprinkler head, temporarily remove it and allow the water to run freely for a few seconds. This process, known as flushing, clears the line of any debris, such as PVC shavings or dirt, which may have entered during cutting. Debris left inside the line can clog the sprinkler head’s internal filter or nozzle.
After the flushing is complete, the sprinkler head is reinstalled, and the zone is tested for proper coverage and spray pattern alignment. The final step involves carefully backfilling the trench, ensuring that the soil is tamped down gently around the pipe to stabilize it without causing undue lateral stress on the new connection point.