I have oil hot water baseboard heat with 3 zones, 1 up and 2 down. The den is a zone all by itself and that is where I get the worst of this gurgling. The odd thing is after about 3 passes, the gurgling stops and returns on next call for heat in that zone. The system was bled after work was done but the gurgling situation remains. The original Taco 007 F5 pump was replaced with a Grundfos UPS15-58FC. Could the Grundfos be the problem? I would imagine if it was the Grundfos that gurgling would not disappear?
I have a Honeywell SuperVent installed and still have this weird problem. I don't see any leaks, so I am baffled as to what is causing this problem. My unit is an Energy Kinetics EK-1 with their hot water tank.