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.