单项选择题
A.water in the fuel oil
B.excessive cycling
C.high fuel oil pressure
D.improper burner maintenance
单项选择题 The purpose of the programmed purge cycle on an automatically fired auxiliary boiler is to（）
单项选择题 The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to（）
单项选择题 Diesel engine waste heat boiler construction is usually of the fire-tube or（）