A layover heating system (89) for a locomotive is provided. The layover heating system (89) is adapted to be used in conjunction with a conventional locomotive cooling systems. The layover heating system (89) includes a water tank and pump (90). A layover heater (92) heats fluid in the layover heating system (89). An orifice (98) is provided to control the flow Of fluid in the layover system (89) to generally balance the pressure on either side of the locomotive radiator. In this manner, fluid flow through the radiator is minimized, minimizing heat loss at the radiator. A variable orifice may be used that is adjustable in response to a signal generated from pressure sensors on each side of the radiator and processed by a central processing unit.