Tub Supply Lines
Tub supply lines come in a a variety of installations to suit your bathroom setup, your tub installation and your preferences. If your rough-in is coming from the wall, tub supply ells are used to adapt stainless steel supply lines. The ells allow the faucet to work with 1/2" IPS fittings.
A Few Important Tips:
Codes and ordinances vary, so consult with a local profession should you have detailed installation questions.
Tub supply lines cannot be bent to vary the spread at the floor. If you have plumbing roughed in on unusual centers, either change the plumbing rough-in or use tub ells with braided water lines.
Typically made from high-quality cast brass, tub supply lines (except freestanding lines) can be easily cut to the correct length for installation.
Avoid over-tightening all connections. Cast brass is one of the best materials for plumbing pipes and valves, but it will crack or split if over-tightened. Using a box wrench, tighten 1/4 turn. Check for leaks. If you find leaks, tighten 1/8 of a turn until leaks stop.
Here are a few types of supply line configurations to help you as you shop or prepare for your new tub purchase.
Single-Offset Supply Lines
Single-offset supply lines are used when the roughed-in pipe at the floor is aligned with the tub faucet holes. If the faucet has 3-3/8" centers, the supply lines will be roughed in at 3-3/8" centers. For 8" centers, the supply lines will be roughed in at 8" centers.
Double-Offset Supply Lines
Double-offset supply lines are most popular for wall-mount faucets with 3-3/8" centers. The supply tubing is angled and slopes slightly outward from the faucet. At the floor, the plumbing should be roughed in at 8" on centers.
Straight Supply Lines
Straight supply lines are used for deck- or rim-mount faucets and are aligned with the faucet holes. For a tub faucet with 7" centers, the supply lines would be roughed-in at 7" on centers in the floor.
Freestanding Supply Lines
Freestanding supply lines are made from heavy-gauge brass tubing designed to support the weight of the faucet. These supply lines must be securely anchored to the floor. Centers are variable depending on the spread of the faucet, but most applications use 7" centers.
Pressure Balance Supplies
Pressure Balance Supply Kits are a variation on the double-offset supply lines. Pressure balance kits work by maintaining a constant temperature at the faucet. They cannot be adjusted and do not have a thermostat to regulate a maximum temperature.