Gas and Oil Home Heating Furnaces - Replacing Water in Radiator pipes

Everyone probably knows the answer to this question except me. I have a Weil-McClain hot water boiler system with copper/fin radiators and four zones. I wanted to replace one of the radiators on the second floor, so I turned off the water to the system (boiler is in the basement), drained the zone and replaced the section. But now I don't know how to get water back into the pipes. The radiator I replaced has a vent valve, so I opened it up and turned the water back on. Nothing seemed to happen, so I turned up the zone thermostat; the boiler fired up, and the pump started. A little bit of water came out of the vent, but there is still mostly air in the pipes. So before I really screw things up, can someone describe the correct way to do this?
Thanks.

Don't feel bad about not knowing the answer. I have heard more screwy ways to bleed radiators from people who should know how to do it than I can shake a stick at. You haven't done anything wrong. And you won't cause any damage by not bleeding the air correctly. You will just waste a lot of time and get frustrated. With some pressure in the system. Somewhere between 10 and 15 psi, and the circulating pump NOT running, open the vent on the radiator until you get water out. You don't need any quantity of water, just water. You may not get all the air at the first venting, so wait a few days and try it again. The only catch is making sure there is pressure in the heating system when you bleed it. If there isn't enough pressure, you just can't do the job.

Ken

check to see if you have a fast-fill lever on your pressure regulator. if you do, lift it to fast-fill position and let the pressure build. place a bucket under the pressure relief valve or have someone watch the pressure gauge while you bleed the radiator. if it starts to get near 30psi shut the fast-fill off. once filled, bring the pressure back down to about 12psi or so depending on the height of the radiator farest away. 2.31ft per 1 psi i think

I'm not too comfortable with that last suggestion. If you trip the safety relief valve, it may not close completely and you will have another problem on your hands. Also, you really don't want more than 15 psi in the system. He also didn't explain how to get the excess pressure out of the system. If you use the boiler drain valve, you may get an additional surprise when you close it and find that it still continues to leak. If all you want to do is bleed air, try not to get yourself into any other situations that will require you to have to call a tech for service, or you will regret ever trying it yourself.

to allow the water to push the air out, it will need to be able to get there. Kill the emergency red switch at the top of the stairs...Open MANUALLY the zone valve...it has a small lock lever to force it open and hold it there for you. look at the boiler pressure gauge, it should read 12 PSI minimum on a two story bldg...18 PSI on a three story. Open the coin vent on the basebopard heater and purge some air and water out till it gives a steady stream of water for 30 seconds or so. Purge the other zones the same way because the most likely all have air now. When complete put the locked arms back to the relaxed position and turn on the emergency switch and raise the set point on that zone only...you will most likely have to do this several times...I'm wondering...did you replace any of the TEE fittings? :(

more than 15 psi in the system won't hurt a thing and if he can't figure out how to solve the pop safety or boiler drain leaking, then he needs to call a tech in the first place.