| 摘要 |
A fresh air heating unit has a casing (2) containing a stale air flow path (25) and a fresh air flow path (14). Combusted gas products from a gas burner (29) are mixed with the fresh air to heat it to a desired temperature before it is discharged into an enclosure. The two paths extend through a heat exchanger (15) and the rate of flow of stale air driven by a fan (26) through the casing is substantially equal to the rate of flow of fresh air driven through the casing by a second fan (21). As the rate of flow of fresh air from the casing into an enclosure is substantially matched by the rate of flow of stale air from the enclosure, and heat is transferred between the two air flows by the heat exchanger (15), a total replacement of air in the enclosure at a relatively high rate can be sustained in an economically viable manner. The level of noxious combustion products in the enclosure and produced by the gas burner (29) can thus be kept beneath that regarded as harmful by health authorities. |
