Asked in
Heating Ventilating and Air Conditioning
Home Appliances

How do you bleed a boiler?


User Avatar
Wiki User
February 17, 2008 12:34AM

You willl have a valve that separates the (heated) return from the (heated) supply. Make sure your system is off; shut this valve. Turn off or shut valves to all zones except one. Turn on (city or well water) water supply valve. Most systems shouldn't go over 25 pounds pressure (12-15 is about right) and are usually automatically regulated, but you might want to keep an eye on that or you could blow the relief valve (big mess). There is usually more than one drain. Look for the one that would give you a complete loop through the system the way the valves are now turned, from the (city or well water) supply, through the boiler (most likely but it might be located elsewher in the system), through the zone, and *then* to the drain you're about to open. If it's two feet of pipe to the drain, *it's the wrong one*. Open the drain slowly, you need to make sure water goes through the whole thing and forces the air out. Repeat for each zone. Remember to turn all of the valves back on when done. Note there are a ton of different configurations, most significant being where each zone has its own motor, or where each zone is simply valved off (which is how I described it above). common sense should get you from the above to what you need, just remember the goal is to give the water one & only one path. Then, repeat for each path possible in your system.