Air valve sizes

Bill Wilson

After being lucky enough to find your website, and doing some quick reading, I believe my problems are caused by one or more bad air valves in a steam radiator system. Prior to replacing my oil fired furnace 5 days ago, I had a problem with mid-cycle banging under an upstairs bedroom floor, as well as water contstantly leaking from the air valve in the same room. For years I captured this in a funnel running to an old roasting pan, which on colder days would have to be emptied twice a day, causing me to add water to the boiler every other day at the worst. Since installing the newer, smaller Weil-McLain unit, the banging has all but disappeared, and I get hardly any water discharge from the air valve. That's the good news. Unfortunately, after topping off the boiler on Monday evening, this morning, only 36 hours later, the water level was low enough that the low water shut-off valve kicked in. This wasn't a mid-cycle low spot caused by the condensate not returning fast enough. The temp in the house was well below the thermostat setting. Upon adding water to the boiler, the furnace operated normally. While reading passages on your website, language concerning hissing and spitting, and window condensation struck home. If my diagnosis of needing one or more valves seems plausible, then my question is how do I determine the correct size vent holes? I know from the reading the relatively larger radiators need larger vents. I believe the vent sizes are identified by number, also, and I don't know if the smaller numbers are smaller vents, or vice versa. If you think something else is going on, I would be interested in hearing what you think(I realize it's hard to diagnose a patient without being there). BY THE WAY, THIS IS A ONE PIPE SYSTEM. When responding, would you please send copies to TBILL1@optonline.net and wwilson@pershing.com. Thanks much for any advice you can offer.