An apparatus, comprising: a gas flow chamber on a first side of the apparatus having an air-fuel mixture inlet , a catalyst compartment containing a catalyst member and at least one tortuous combustion products pathway for moving combustion products from the catalyst compartment to an exhaust gas port ; a fluid warming chamber on a second side of the apparatus to conductively receive heat generated in the gas flow chamber and having a fluid inlet connectable to a source of fluid, a fluid warming surface and a fluid outlet connectable to a patient; an air-fuel mixing chamber having an air inlet , a fuel port and an air-fuel mixture outlet; a motor-driven air mover having an air intake to receive ambient air and an air outlet disposed to discharge air to the air inlet of the air-fuel mixing chamber ; a fuel assembly comprising a fuel storage tank , a valve to receive a stream of fuel from the tank and a fuel port connector coupled to provide fuel from the valve to the fuel port of the air-fuel mixing chamber ; a battery to provide electrical current to operate a motor to drive the air mover ; and wherein a stream of an air-fuel mixture emerging from the air-fuel mixing chamber enters the catalytic compartment containing the catalyst member and combusts to create a stream of heated combustion products; wherein the combustion products flow through the at least one tortuous pathway to the exhaust port where the combustion products are liberated to the atmosphere; and wherein a stream of fluid from the source of fluid enters the fluid warming chamber through the fluid inlet , is warmed along the warming surface and is removed from the fluid warming chamber through the fluid outlet . a gas flow chamber on a first side of the apparatus having an air-fuel mixture inlet , a catalyst compartment containing a catalyst member and at least one tortuous combustion products pathway for moving combustion products from the catalyst compartment to an exhaust gas port ; a fluid warming chamber on a second side of the apparatus to conductively receive heat generated in the gas flow chamber and having a fluid inlet connectable to a source of fluid, a fluid warming surface and a fluid outlet connectable to a patient; an air-fuel mixing chamber having an air inlet , a fuel port and an air-fuel mixture outlet; a motor-driven air mover having an air intake to receive ambient air and an air outlet disposed to discharge air to the air inlet of the air-fuel mixing chamber ; a fuel assembly comprising a fuel storage tank , a valve to receive a stream of fuel from the tank and a fuel port connector coupled to provide fuel from the valve to the fuel port of the air-fuel mixing chamber ; a battery to provide electrical current to operate a motor to drive the air mover ; and wherein a stream of an air-fuel mixture emerging from the air-fuel mixing chamber enters the catalytic compartment containing the catalyst member and combusts to create a stream of heated combustion products; wherein the combustion products flow through the at least one tortuous pathway to the exhaust port where the combustion products are liberated to the atmosphere; and wherein a stream of fluid from the source of fluid enters the fluid warming chamber through the fluid inlet , is warmed along the warming surface and is removed from the fluid warming chamber through the fluid outlet . <EOS>