Since the vacuum tube solar water heater has been born, the insulation work of the side overflow pipe is often neglected. Now conventional practice is at the side of the overflow pipe is connected with a three-way, the formation of an uplink channel and a downlink channel, downstream channel connected with the water return pipe, when the water tank is filled with water and a portion of the overflow of water can be along the downstream channel flows back into the room, the other part of the uplink channel overflow. Not to spill the water, water tank inside and outside space directly connected, when the internal temperature of the water tank is higher than the external temperature, the side overflow pipe of the uplink channel to create the conditions for the cold and hot air convection, the convection enhanced with the increase of temperature difference, we in the winter can often be seen side overflow pipes to take hot gas is the hot and cold air convection. In severe cold area. Hot upwelling of cold, water vapor will condense into ice blocking of pipeline, the water tank is unable to exhaust air, endangering the safe use of the water heater.

Side overflow pipe is connected with a three pass, not easy to implement the package insulation measures, now put into use of the solar water heater, overflow pipes most directly exposed in the air. Because of the overflow pipe and the water tank are welded together, the temperature will be transmitted through the overflow pipe, spread to the outside atmosphere.