and a recycled water collecting inlet 13 disposed at the lower portion of the water heater body 1 a hot water outlet 12 is disposed at the top of the water heater body 1 for supplying the hot water in the water tank 2 to an area to be heated fig1 the liquefied petroleum gas lpg is a compressed petroleum gas or a liquefied hydrocarbon gas a compressed or liquefied gas is obtained as a by product in petroleum refining or natural gasoline manufacture e g butane isobutane propane propylene butylenes and their mixtures lpg is colorless noncorrosive nontoxic and has a flash point of 100 u00b0 f 74 u00b0 c and an autoignition temperature of 800 u00b0 1000 u00b0 f 426 u00b0 537 u00b0 c in operation after the desired temperature for the water in the water tank 2 is set with the predetermined temperature gauge 14 by operating the control box 7 so as to utilize the lpg for the heating source of the water in the water tank 2 the burner 8 disposed within the combustion chamber 3 is ignited therefore the water in the water tank 2 is uniformly heated through the plurality of water conduits 10 then the fire flame may be controlled by the fire flame monitoring member 19 and is directed downward by the fan 9 the fire flame and any smoking are exhausted through the flue pipe 4 at this time the temperature of the water in the water tank 2 meets the predetermined temperature of the predetermined temperature gauge 14 and the control box 7 causes the lpg supply from the lpg inlet 20 to stop when the temperature of the water in the water tank 2 decreases below about 10 u00b0.