2. No fuel is to be used other than wood pellets or wood chips, but excluding any such pellets or chips which contain halogenated organic compounds or heavy metals as a result of treatment with wood-preservatives or coatings.
2. No fuel is to be used other than wood pellets or wood chips, but excluding any such pellets or chips which contain halogenated organic compounds or heavy metals as a result of treatment with wood-preservatives or coatings.