| 摘要 |
It is described a forced draught type CM wall boiler, in particular an open room type (Bf) or sealed room type (C), equipped with a draught fan (7) and adapted to be connected exclusively to flues (2.2) permitted for the evacuation of flue gas under pressure. According to the invention, said CM wall boiler is further adapted to be connected to flues (2.1.) for flue gas evacuation in pressure drop, the boiler being equipped with means (AR, 5, 6, 7; 11, 11.1, 6.1) adapted to maintain the flue gas entry pressure in the flue (2.1) equal to the atmospheric pressure even in the presence of unforeseen disturbance or circumstances. <??>According to a first variant of the invention, this can be obtained with the application of an antirefouler AR device that necessarily maintains the flue gas pressure at the same level as the environmental pressure. <??>According to a second variant, particularly useful for sealed room wall boilers, the fan speed (7) is maintained at values that will not generate residual pressure at the wall boiler outlet; this is obtained through an electronic control unit on the wall boiler, that receives pressure signals from an electronic pressure switch (11) installed at the connection to the flue (2.1). <IMAGE>
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