Problems with Noisy Flapper on Weil-McLain Oil Boiler

[willshak]

On 2/7/2005 2:29 PM US(ET), frank1492 took fingers to keys, and typed the following:

The exhaust stack on my Utica oil boiler in the basement goes straight up through a shaft in the center of my house and then out the roof. It must be 25' long. The gravity balanced flapper is in the exhaust pipe just above the boiler. When there are high winds blowing outside, my flapper flaps. Not big flaps, but just enough to be able to be heard when I am in the basement. I would suppose that a shorter exhaust pipe would cause more vigorous flapping.

[frank1492]

The head of the bed is directly over the boiler. The boiler is direct-vented through the cellar wall. There are no windows on the boiler end of the house. On windy nights, there is an annoying noise that seems to come from somewhere in the exhaust line. Sounds to me as if there is a gravity flapper in the terminator or elsewhere that is moving back and forth. I was puzzled because I thought the vent on most of these systems was electrically controlled. Could someone help diagnose this problem? Also I'd like to know a little more about what moving parts exist between the point of exhaust from the boiler and the outside. Also, is there a cure? (Note: This question is being asked on behalf of some friends who recently bought a house that's about three years old. At present, I do not have the boiler model, but could obtain it if necessary.) Thank you for your help. Frank P.S. The boiler is a Weil-McLain