| 摘要 |
PURPOSE:To rapidly carry out suppression of overchute and further to extremely lower its peak level by providing braking control means which actuates changeover means for applying inverse phase braking to a fan motor in response to a detection signal of a detection signal of an overchute detection circuit to thereby apply braking thereto and restoring the changeover means in correspondence to a detection signal from rotational speed detecting means to release the braking. CONSTITUTION:When the increasing temperature of hot water exceeds an overchute detected temperature T, a relay 22 is turned ON, and a contact 22a is connected to a changeover terminal X. As a result, inverse braking is applied to the fan motor 5, whereby the fan motor 5 rapidly reduces its rotational speed, and the wind quantity decreases without time delay. Accordingly, the quantity of gas supplied to the burner decreases. As a result, the increase in the temperature of hot water is rapidly suppressed. Thus, when the rotational speed of the fan motor 5 exceeds the minimum rotational speed, a discrimination signal is outputted to control means of the overchute detection circuit, thereby the relay 22 is turned OFF, and the contact 22a is connected and changed to a changeover terminal Y. As a result, the fan motor 5 is released of its inverse phase braking. |
