Abstract
An investigation was undertaken to determine the levels of house depressurization against which naturally vented gas-fired furnaces and domestic water heaters can establish and maintain safe venting of combustion products. Also investigated were the maximum depressurizations of buildings which could be achieved by the installed fans and fireplaces. A test procedure was developed whereby venting failure can be artificially induced by depressurizing the house with a large fan. Results show that it is highly improbable that the maximum depressurizations found in houses by operating all the fans and the fireplaces at the same time will cause the chimney to vent improperly even in conditions under which venting failure would be most likely to occur (cool temperatures, low wind, cold chimney, large number of exhaust fans, weak venting furnace/chimney combination, relatively tight house).
