The easy way, is to turn the electric off, relieve the system pressure,
replace that "small round part with what looks like a tire valve stem on the
top of it" (automatic air vent), add water to the system, turn the electric
on, and wait a few days. The cap is just there to close it off if it starts
leaking. It should normally be loose. Most times, the air will eventually
work it's way around and come out that vent.



The harder, but quicker and more positive way of getting the air out, is to
first turn off the electric, then close all (return line) shut off valves
that are between the "faucet" (boiler drain valve) and the heater. Then put
a hose on one of the drains, purge the air out by opening the drain valve,
repeat the process on each zone, and then open the shut off valves. With
this method, you need to maintain constant system pressure.



"Brian" wrote in message
...

I have a small problem I need help with. I have forced hot water with
baseboard heat. My expansion
tank sprung a leak last week. I replaced it by spinning the old one off
and spinning the new one
on. In the process I lost some water. My problem is that now when the
heat comes on I hear water
running through the baseboards. I know there's a way to bleed the zones
but I have forgoten how. I
also remember it has something to do with the faucet and shut off valves
at the end of each zones
run back to the furnace. One last thing, on the top of the manifold that
the expansion tank
attaches to, there's a small round part with what looks like a tire valve
stem on the top of it. It
has a cap on the stem and when I loosen the cap, water starts dripping
out. Is this some kind of
bleeder ??? Do I leave the cap loose and let it drip ????

Thanks
Brian