Hammering in my hot water heating boiler
I have a zoned in floor hot water heating system that is hammering. The system hammers in the boiler when I have only one zone on. When more than one zone calls for heat, then there is no hammering.
* I have installed spiro vents to remove all of the air.
* I have checked the pump, and it is fine.
* If I open a bypass valve to increase the circulation through the boiler, the hammering goes away.
I am thinking that I am not getting enough circulation through the pipes in the floor. Water is turning to steam in the boiler and hammering.