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Negative pressure can occur when there is not enough ventilation in a home and an exhaust fan or range hood is operating. If an open flued gas space heater is operating at the same time as an exhaust fan, it may cause the gas heater to malfunction.
An open flued heater draws air from the room to feed the fire and combustion products are then moved outside via a flue. However, inadequate ventilation and use of exhaust fans can draw carbon monoxide (and other exhaust gases) back into the room in certain circumstances.
The exhaust fan causes a slight reduction in air pressure within the room where the heater is running and can cause a partial or full reversal of the flow in the appliance’s flue, essentially drawing the products of combustion back into the room.
This may cause high levels of carbon monoxide to build up in the room. Carbon monoxide is a colourless, odourless gas which can cause serious health issues and in some cases, may be fatal.
With houses becoming more energy efficient and therefore airtight and increasing use of powerful exhaust fans, the circumstances leading to negative pressure are becoming more common.
Simple steps to resolve negative pressure
If you have an open flued gas space heater, there are some simple steps you can take that will keep you safe:
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