My (new) baseboard heating system is causing a racket, and I've been trying to figure out a way to properly purge the air from it. Following the flow of water through one zone of my four-zone system, it goes:
Furnace output → Circulating pump → Expansion tank → Hand valve (A) → Thermostat-controlled valve → Spigot (A) → Radiators throughout house → Hand valve (B) → Water main input → Spigot (B) → Furnace input.
I've been trying to figure out a way that I can force the air in the pipes out with new water from the main. If there were a spigot right before hand valve (B), for example, I could close hand valve (B), open the spigot right before it, and let the water pump through the system and out that spigot to purge the air. However, the spigot (A) is instead on the other side of the piping through the radiators.
I have read about using the pressure from the main line rather than the pump to purge the air, and I've also heard mention of "reverse purging" (which I suspect my system might be set up for, given that the spigots immediately follow the zone control valves). I'm still not sure what to do, though—any suggestions?