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2 Methodology

2.1 Selection of heaters

All households involved in the study were participants in a Warm Homes pilot project funded by the Ministry for the Environment. Households were selected on the basis that they had a suitable heater and were willing to participate in the emissions testing programme. As part of the programme, chosen households had a pre-1994 wood burner replaced with a pellet burner supplied by Nature’s Flame. Of the four burners tested, three were Sherwood Industries EF2 free-standing fires and one was a Sherwood Industries EF3 Meridian free-standing fire.

2.2 Fuel

All householders fuelled their burners with pellets from Nature’s Flame. Pellets from both plants (Rotorua and Christchurch) were burned during the testing. The onsite technician noted that pellets from the Rotorua plant appeared to be longer, resulting in lower feed rates and reduced outputs.

2.3 Emissions sampling

A portable emissions sampler was installed in each household for the duration of the tests. Results from the sampler can be used to calculate an emissions rate in g/kg (dry wood basis) independently of any information recorded by the householder. The method employed by Applied Research Services is based on the Oregon Method 41 (OM41), also known as the Condar Method. Filters on the sampler were changed daily, and the sampler was run for seven days in each household. Further details on the sampler are given in Appendix 2.