The dangers

Along with the Consumers’ Institute and BRANZ, we strongly advise avoiding the use of unflued, LPG or other bottled gas heaters in your home.

Unflued gas heaters are banned in Canada and some U.S. and Australian states. The U.S. Environmental Protection Agency has recommended warning labels on all such gas appliances.

Unflued and bottled gas heaters produce toxic by-products such as carbon monoxide, sulphur dioxide and nitrogen oxide.  In non-ventilated rooms these heaters can deplete oxygen levels causing incomplete combustion. The by-products identified above can cause feelings of fatigue, and worsen heart and respiratory problems, especially in asthma sufferers.

Moisture generated by unflued and bottled gas heaters

In addition to the health and safety risks, (including the risk of skin burns and of clothes or other items catching fire), unflued and bottled gas heaters generate large volumes of water vapour, often doubling or trebling the total amount of moisture produced in the average home. 

Even modest use of an unflued or bottled gas heater in winter will generate higher levels of moisture, significantly increasing mould, mildew and condensation problems, creating health risks and damaging furnishings, window frames and personal effects. 

According to BRANZ, an unflued or bottled gas heater produces around 200mls (0.2 litres) of water vapour for each kilowatt of output, each hour it is operating.  For example, a 2kW gas heater will generate 400mls of moisture (0.4 litres) an hour, equivalent to a 2 litre milk container of water being spread around inside your home every 5 hours of operation.

Important information for DVS customers

While DVS ventilation systems have been proven to be highly successful in controlling ‘normal’ levels of moisture and condensation in homes, they may not be fully effective in controlling the very large quantities of moisture produced by unflued gas heaters. Therefore, because your choice and use of home heating is outside our control, we cannot guarantee that the DVS will be able to achieve an adequate level of condensation and moisture control in every instance. 

Where unflued or bottled gas heaters are used only occasionally or over short periods of time as supplementary or secondary heating, DVS ventilation systems will generally be able to achieve a reasonable level of condensation control (with the exception of very cold or extreme weather conditions). But where unflued, LPG or bottled gas heaters are used over longer periods of time or as the only or main form of heating, a DVS ventilation system may not be able to meet our performance expectations and achieve an acceptable level of condensation or moisture control. 

To reduce the high levels of moisture, we strongly recommend you replace your unflued or bottled gas heaters with alternative forms of direct or indirect heating such as:

• Fujitsu heat pumps
• Tempervents
  
• Electric panel heaters
  
• Flued gas heaters
• Solid fuel burners (e.g. wood burners)