| 摘要 |
<p>A gas-fuelled storage water heater intended to provide reduced gas consumption compared to generally similar conventional types, which has: an upright cylindrical storage tank that stores heated water and which has a tubular heat exchanger flue passing axially through the tank; the flue terminating closely above the top of the tank; a combustion chamber beneath the tank housing a main burner that heats water in the tank and a pilot burner which remains alight when the main burner is not alight; a duct communicating with the top of the flue; which includes a vertical leg with a surface that makes direct contact with an external surface of a vertical wall of the tank; the tank, flue and duct being enclosed by heat insulation; where the duct dimensions are chosen to satisfy the condition that, when the pilot flame alone is alight, an average buoyancy force exerted on gases in the flue substantially balances an average opposing buoyancy force exerted on gases in the vertical portion of the duct.</p> |
