How do you bleed a hot water heating system?
Hot water baseboard heating does not have a bleeding valve on each heater. Air must be bled from the system at the furnace. You should find a tap to attach a garden hose near the circulating pump. Run the tap to a sink or outdoors. Open the tap and manually open one zone valve at a time to bleed air. Place the end of the hose into a bucket so you can watch for bubbles. After all zones have been bled close the tap. Above the expansion tank should be a small plastic screw which should be loosened to allow extra air to escape. I have pictures and other info on my web page.
