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Home > HNE Population Health > Environmental Health > Unflued Gas Heaters in Schools

Unflued Gas Heaters in Schools

Pilot School Heater Survey

During winter 2005 Hunter New England Health participated in the NSW Health School Heater Surveillance Program. NSW Health initiated this pilot surveillance program in non government schools to characterise the prevalence and type of unflued gas heaters in operation, to provide support for the implementation of ventilation and maintenance policies, and help highlight any areas that may require remediation. NSW government schools were not included in the survey because they already have an ongoing program of replacement of standard emission heaters with low-nox heaters, in addition to operating guidelines for unflued gas heaters with specific cross-ventilation requirements and signage.

Unflued gas heaters release combustion by-products, with associated health risks, directly into the room where they are operating.

Unflued gas heaters are categorised by their level of nitrogen dioxide emissions. All heaters sold in NSW must comply with the current Australian Standard that specifies NO2 emissions must be less than 5 nanograms/Joule (ng/J). Heaters with lower NO2 emissions (< 2.5ng/J) are referred to as low-nox heaters. Studies conducted in Australia suggest that the levels of NO2 in a room where a heater is operating is dependent on several factors including type of heater; age of heater and maintenance record; heat differential achieved; and adequacy of ventilation.

Health effects caused by exposure to air pollutants from unflued gas heaters can occur immediately at the time of exposure or be delayed. The effects will depend on the type and amount of pollutant exposure. For example, exposure to NO2 can cause irritation of the respiratory tract and shortness of breath. People with asthma and other respiratory diseases are particularly susceptible to the effects of exposure to NO2.

Conclusions of the Survey

Around 20% of non-government primary schools in NSW used unflued gas heaters with the prevalence of heating type varying by geographic area. Standard, rather than low-nox, was the predominant type of unflued gas heater used. Approximately 50% of schools surveyed stated that they had an UGH maintenance policy and 40% of classrooms visited when their UGH was operating had adequate ventilation as judged by DET guidelines. Based upon limited sampling in “worst case” scenario classrooms nitrogen dioxide concentrations were likely to be higher where there was a standard unflued gas heater and ventilation guidelines were not met. The highest concentrations of nitrogen dioxide were associated with both low-nox and standard heaters, irrespective of any maintenance policy. The extent of the surveillance program was limited by a mild winter during 2005.

Recommendations

• All schools that use unflued gas heaters should have an unflued gas heater maintenance policy and existing maintenance policies should be reviewed.
• Schools should be aware of ventilation advice. Cross ventilation stickers on heaters are a useful reminder of this requirement (see below).
• Non-government schools should consider a staged replacement of standard unflued gas heaters with flued gas or other heating types that avoid internal emissions.

Ventilation Requirements for Unflued Gas Heaters in Schools

• Standard Heaters – identified by accessible visible burner with blue flame.
  • On calm days (little wind) rooms with doors opening onto internal circulation areas such as a corridor or practical activity area, the door should be open with windows open a total of 1600 sq cm (two casement windows open 10 cm).
  • If the room has an external door then a window opening of 800 sq cm is required (one casement window open 10cm) with the door open.
  • On windy days opening of doors and windows can be reduced by a quarter.

• Low Nox Burner Heaters - marked as low Nox (with ‘LB90’ on name plate), with burner unit shielded from view by fixed panel
• In classrooms which can be cross-ventilated, open the top sash of at least one window on each side of the room to approximately 50mm. Where other types of windows are in use an equivalent opening can be estimated.
• Note:  This should give adequate ventilation during still or mild wind conditions.  During higher wind conditions, the windward side window could be completely closed, and the opening on other windows adjusted to give an equivalent additional area of opening.
• In classrooms that cannot be cross-ventilated, open the top sash of at least two windows on an external wall by at least 50mm.
• In classrooms which have been fitted with ceiling grilles or other means of fixed ventilation, specific advice from the ventilation contractor on ventilation needs should be provided.

This illustration can be used as a template to make stickers to place on heaters to remind teachers about ensuring appropriate ventilation.

Maintenance Requirements for Unflued Gas Heaters in Schools

• The heater air inlets and exhaust grilles should be kept free of dust with routine cleaning.
• An authorized service agent should service the burner before the start of every winter.s