Abstract: A cylindrical valve body is secured within the body of the heater and includes a venturi inlet to reduce flow restrictions through the valve. A flexible flap valve spans the inner bore of the body at approximately 45.degree. so that it only has to be moved through 45.degree. to be fully opened or fully closed, and secured so that gravity aids in the seating of the flap valve in the closed position. A strip type retainer engages grooves in the side walls of a slot at the top of the body and engages the upper part of the flap valve and holds it in position when the valve assembly is incorporated in the heater and a projecting lug from the valve body engages an aperture in the heater body to position the valve assembly correctly relative to the heater assembly.

Abstract: A reservoir has an electrical heating element therein connectable to a power line and the reservoir is connected in series with a coolant carrying hose which in turn is connected to the coolant system of an automobile engine or the like. The reservoir is provided with an inlet connection and an outlet connection both situated adjacent the upper side of the reservoir. The inlet connection has a one-way valve allowing coolant in only, and includes a ball which has a specific gravity less than the specific gravity of the coolant so that the ball floats in the coolant and closes off the inlet connection when the coolant level is adjacent the upper side of the reservoir. The outlet connection has a one-way valve allowing coolant out only and includes a ball which has a specific gravity greater than the specific gravity of the coolant so that the ball normally engages the valve seat and is only displaced if and when the pressure of the coolant and/or the air in the air space above the coolant level increases.