vent values open 2-5 minutes after sys shuts down on steam heat

jack fitzgerald

Once the boiler shuts down within 2-5 minutes the radiator on the first floor of a house built in 1912 opens up. This
radiator has a vari-vent on it. the radiator heats up very
well. But once it opens very shortly after the boiler shuts down, air going thru this radiator into the mainline causes other radiators on the first nad second floor of the
house to open. I need to be able to retain the heat in the radiators longer. The house is a six-room 2 story house built in 1912 with 8 radiators: one per room, plus a bathroom on 2nd floor and an entry hallway on the first floor. All radiators encept the den(orginal diningroom which opens to living room-the control room) have the
standard adjustable vent values. The valve has the adjustment (plastic wheel) at the base of the vent. The
den I used a vari-vent value because this radiator is on
the end of the loop just before the return to boiler. By using a vari-vent on this radiator you don't have to wait to long for confort ( while watching the boob tube) and it
shortens the time the system will be in operation. Remember, the den is the open room adjacent to the control room (living room). If I am going to heat a radiator to
200 degress or better then why should room temperature air (68-70 degrees) be rushing in thru it just after the system
has finished it's cycle? I am just a numbers guy and trying to learn the mechanics of this system. Any help would be gladly appreciated.