| 摘要 |
This invention relates to air heating apparatus for supplying a stream of warm, fresh air to a space to be kept warm. The invention provides an apparatus (1) for providing a space with a stream of warm fresh air (3), the apparatus including a first heat exchanger (4) provided with mutually-isolated primary and secondary air flow circuits for pre-warming the stream of fresh air with heat extracted from a stream of stale return air (21) taken from the space, the stream of fresh air flowing from the first heat exchanger being further heated by flow through a second heat exchanger (10) which has heat transfer elements (11) internally heated by hot combustion products generated by one or more burners, the combusted products from the heat transfer elements discharging into the stream of stale return air (21) prior to it entering the first heat exchanger (4).
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