Which statement best describes the impact of installing an automatic vent damper on a boiler?

• A. Reduces loss of heated air between cycles
• B. Increases annual maintenance cost
• C. Reduces boiler pressure capacity
• D. Has no effect on efficiency

Answer: (A)

Automatic vent dampers work by sealing off the vent when the boiler isn’t firing. This cut down on heat loss from the flue gases escaping up the chimney between cycles. By reducing this standby heat loss, the boiler uses less fuel to achieve the same heating output, improving overall efficiency. The other points don’t describe the main effect: it doesn’t inherently raise maintenance costs, it doesn’t change the boiler’s pressure capacity, and it does influence efficiency rather than having no effect.