Monoflo Tees are usually installed on the return side of heaters with the middle portion of the tee facing upwards. Looking at the tee this way, the left side is the where water enters, the middle (on top) is where air escapes, and the right side is the outlet. Sizing is done with the first number representing the inlet and outlet and the second number representing the middle.
Monoflo Tees can be found at www.supplyhouse.com
