What Is the Proper Way to Purge Boiler Zone Valves On a Hot Water Boiler?

Turn the boiler off and check to make sure that the self-feeding water valve is attached to the boiler.

Record the pressure level inside the boiler tank. You'll use this number when restarting the boiler after you purge the air from the system.

Open the valves that carry water to the different areas of your home, and close all of the shutoff valves.

Connect a hose to a spigot on the line that returns cold water back to the boiler from the rest of the house.

Place the other end of the hose near a floor drain; if one is not available, place the end of the hose into a bucket.

Drain water from the line by opening the spigot and the self-feeding valve. Allow the water to drain until there are no more air bubbles in the water being drained. Watch the pressure gauge as you drain the line. If the pressure in the line goes above 25 pounds per square inch, release the self-feeding valve until the pressure in the line goes beneath 25 psi.

Turn off the spigot and release the self-feeding valve once the line has been purged. Allow the pressure level to return to normal.

Purge the air from the pipes in the other heating zones, using the same process you used to purge the pipes in the first zone.

Open all of the shutoff valves and close all of the zone valves.

Look at the water pressure gauge on the boiler tank. When it reaches the level it was when you began the process, restart the boiler.