Room chamber assessment of the pollutant emission properties of (nominally) low-emission unflued gas heaters

Pollutant emissions from unflued gas heaters were assessed in CSIRO's Room Dynamic Environmental Chamber. This paper describes the chamber assessment procedure and presents findings for major commercial heaters that are nominally "low-emission". The chamber was operated at controlled conditions of temperature, humidity, ventilation and air mixing, representative of those encountered in typical indoor environments. A fixed rate of heat removal from the chamber air ensured that the heaters operated at constant heating rates, typically similar to6 MJ/h which simulated operation of a heater after warm-up in an insulated dwelling in south-east Australia. The pollutants assessed were nitrogen dioxide, carbon monoxide, formaldehyde, VOCs and respirable suspended particulates. One type of heater was lower emitting for nitrogen dioxide, but emitted greater amounts of carbon monoxide and formaldehyde (the latter becoming significant to indoor air quality). When operated with low line pressure or slight misalignment of the gas burner, this heater became a hazardous source of these pollutants. Emissions from the heaters changed little after continuous operation for up to 2 months.