I have hot water heat with 4 zones. 3 work fine, but the 4th in my basement will not work. The value opens when called for , ( I have removed the valve and it operates fine when switched on)but no wate moves.
I increased the pressure from 12 to 16 lbs to see if there was an air lock but still no movement. The raditors are on the floor of the basement and have no air bleeds
and are below the boiler. My last hope is to to try to back flush with a hose from an outside faucet to get the line moving. Any other ideas?