While we would prefer balancing the ventilation system it's not always an option. Many condominiums, hotels, appartments and high-rise buldings are desinged for negative indoor air pressure. Often a vent, typically in the bathroom, exhausts air constantly, creating negative indoor pressure to draw fresh air in from the outside through small holes in a couple of the windows or from the hallway. Of course the negative indoor air presure would tend to pull air down the chimney too.
Sometimes a make-up air system can be installed to balance the ventilation system and insure that the indoor air pressure is neutral or positive - just as we recommend in a single family home.
Chimney fans can also be used to overcome the negative indoor air pressure and vent the fireplace. Gas Rumford fireplaces with exhaust fans and automatic dampers work fine in condos, hotels, appartments and high-rise buldings.
Wood-burning fireplaces can be more complicated. It's always best to balance the ventilation system so the chimney draws even when cold. A chimney fan may be used but it may have to be kept on long after the fire is out to make sure all the smoldering products of combustion are exhausted. Then a gasketd tight-fitting damper must be manually closed to prevent downdrafts. The automatic dampers used of Gas Rumfords are not designed to be used on wood-burning fireplaces.
Buckley Rumford Fireplaces
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