IT'S TIME TO SOUND THE ALARM REGARDING HIGH CAPACITY EXHAUST DEVICES

There are more high capacity exhaust appliances coming on the market. These appliances, unless installed with provision for fan-supplied make-up air, can severely depressurize modern houses. This can lead to problems with venting of combustion products, soil gas infiltration and infiltration of carbon monoxide attached garages. Where these appliances are installed in a new building, the industry may find it difficult to comply with code requirements for fan-supplied make-up air if the appliances have not been designed with provision for inter-connection. Of more serious concern is the situation where the owner of an existing house simply purchases and installs one of these appliances and is unaware of the potential problems such appliances can create. The appliance industry does not seem very aware of the problems these devices can create in even a moderately tight house. This paper reviews the technical issues involved and discusses possible means of addressing them.