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Water Treater · 10-28-2008, 08:42 PM

I would not reverse direction of water flow. Best to solve the root cause of the problem, which sounds like it's AIR IN THE PIPES.
The smallest amount of trapped air can (and will!) block water flow and explain the hot/cold water symptoms you describe.
If you bleed all the air from the system and you can still hear air (you should NEVER be able to hear water flowing), you're still introducing air into the system. Check suction side of pump to see if you're s#^&#^&#^&#^&#^&g in air. The air is being introduced somewhere, maybe when boiler (heater) shuts off and water begins to cool in the pipes. When you heat water and then allow it to cool, negative pressure (a vacuum) develops which will suck in air if plumbing connections are not tight.

10-28-2008, 08:42 PM	#14
Water Treater Registered User iTrader: (0) Join Date: Sep 2004 Location: Westwood, MA Posts: 116	Trapped air in forced hot water heating system I would not reverse direction of water flow. Best to solve the root cause of the problem, which sounds like it's AIR IN THE PIPES. The smallest amount of trapped air can (and will!) block water flow and explain the hot/cold water symptoms you describe. If you bleed all the air from the system and you can still hear air (you should NEVER be able to hear water flowing), you're still introducing air into the system. Check suction side of pump to see if you're s#^&#^&#^&#^&#^&g in air. The air is being introduced somewhere, maybe when boiler (heater) shuts off and water begins to cool in the pipes. When you heat water and then allow it to cool, negative pressure (a vacuum) develops which will suck in air if plumbing connections are not tight.