Abstract: A fuel return block has a body with a coaxial inlet and outlet generally perpendicular to the body, a return port communicating with an inlet, and a vent generally parallel to the inlet and the outlet while communicating with the return port. The inlet and the outlet have external threading for connection to a fuel tank and to a fuel line. A common space between the inlet, the outlet, the return port, and the vent has a particular geometry conducive to ventilation of the fuel return block but not allowing escape of fuel through the vent. The inlet secures to a manufacturer's fitting upon the fuel tank so no second opening is required. The fuel return block equalizes pressures of the inlet, the outlet, and the return port preventing tank damage and interruptions to fuel delivery from negative pressure.

Abstract: A fuel return block has a body with a coaxial inlet and outlet generally perpendicular to the body, a return port communicating with an inlet, and a vent generally parallel to the inlet and the outlet while communicating with the return port. The inlet and the outlet have external threading for connection to a fuel tank and to a fuel line. A common space between the inlet, the outlet, the return port, and the vent has a particular geometry conducive to ventilation of the fuel return block but not allowing escape of fuel through the vent. The inlet secures to a manufacturer's fitting upon the fuel tank so no second opening is required. The fuel return block equalizes pressures of the inlet, the outlet, and the return port preventing tank damage and interruptions to fuel delivery from negative pressure.

Abstract: A heating and cooling system incorporates a heat pump that operates conventionally with air drawn from outside the system through its condenser coils that remove heat to the exterior for cooling. In the heating cycle, the condenser motor blower stops and reverses rotation. Outside air is drawn in by the condenser fan, is circulated across the diesel engine and generator, and is blown through the condenser coils outside of the unit. In the heating cycle, a circuit monitors the temperature of the compressor coil and controls the speed of the condenser motor. The heat recovery method of the system maintains power input to heat output ratios in excess of 2:1, even at low outside temperatures. The recovery method also allows the system to operate without defrost cycles. This system may provide auxiliary power, block heat, and battery charging, utilizing a small diesel engine and generator components, and can be installed within a truck, bus, boat, cabin, camper, and the like.