Re: HEATING SYSTEM PRESSURE
Posted by e-plumber on December 12, 2003 at 21:12:53:
In response to Re: HEATING SYSTEM PRESSURE
: I LIVE IN A 2 STORY HOUSE WITH HOT WATER HEAT, WITH OLD STYLE CAST IRON RADITORS AND MY SYSTEM IS BUILDING ABOUT 20 - 22 POUNDS OF PRESSURE. TO MY UNDERSTANDING THE MAX PRESSURE OF THESE SYSTEMS SHOULD BE AROUND 17 LBS. I HAVE DRAINED THE ENTIRE EXPANSION TANK (OLD NON-BLADDER TYPE) AND PRESSURE DROPS TO AROUND 15 LBS. THE PRESSURE THEN REBUILD OVER THE NEXT DAY OR SO. I SEEM TO HAVE SOME AIR IN THE SYSTEM AS WELL AND BELIVE THAT MAYBE CAUSING MY PROBLEM. I'VE BEEN TOLD THAT THE AIR SHOULD BE ABLE TO BE BLEED OUT OF THE HIGHEST POINT OF MY SYSTEM. HOWEVER I'M ONLY ABLE TO BLED IN OUT OF A LOWER POINT ON THE FIST FLOOR (1 RADITOR IN PARTICULAR). IS THE AIR THE PROBLEM? ALSO WILL THE CIRCULATING PUMP PUSH THE AIR AROUND MAKING IT DIFFICULT TO BLEED OUT? tHE ONLY PLACE TO BLED IS ON THE INDIVIDUAL RADITORS.

: i WOULD GREATLY APPRECIATE ANY ASSISTANCE YOU MAYBE ABLE TO PROVIDE. I'M A DO-IT YOUR SELFER AND LIKE TO UNDERSTAND THESE THINGS.

: THANKS AGAIN,
: TOM

Reply:
Normal system pressure is apprx. 6 lbs. per floor above the boiler. To drain the expansion tank, shut the isolation valve and make sure when you're draining it, it's not holding a vacuum. There could be a valve to let air into the tank or part of the drain valve on the tank.
For the system to work properly, all the air has to be removed from each rad. Shut the circulator off when you're bleeding air.
Good Luck. e-plumber


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