[an error occurred while processing this directive]
Posted by HeatPro on December 31, 2005 at 14:31:38:
In Reply to: BOILER EXPANSION TANK posted by JOE on December 31, 2005 at 13:43:38:
As an expansion tank provides a place for extra water made by heating it, it would change the system if it broke. The little device above it is probably the new type of ball valve that is used to isolate the tank when replacement is needed.
As the tank usually hangs below the air scoop, a rupture of the diaphragm would allow the gas content to rise up and into the system, so you would hear noise bubbling through the pipes upstairs.
If the pressure reducing valve is left open to the system instead of closed as recommended by the manufacturer water would replace the air as it is vented. When the air was vented through an automatic vent, the system would no longer have a place to expand to during the heating cycles, so the pressure relief valve (hopefully a working one so the boiler wouldn't burst) would dump cupfuls of water on each heating cycle until you noticed or corroded the system so badly it would require replacing parts.
If the hand valve from the cold water line to the pressure reducing valve is kept closed, water will not be able to enter, so other parts of the system will become expansion vessels, while some heating elements won't heat and you will become annoyed by the noise of the bubbles running through until you find the damaged expansion tank and replace it.