The hot water system of the floor heating system should be operated at about 50°C. The hot water in the radiator heating system is generally about 80°C. It is changed to the floor heating in the central heating system for radiator heating. The following solutions are proposed: The plan; if the district adopts the floor heating reference, the boiler room or the heat exchange station can be built less and the materials and operating costs can be reduced. In general, floor heating adopts aluminum-plastic pipe and PPR composite pipe. Although it can withstand high-temperature water above 80°C, it is certainly not as good as water temperature below 60°C for long service life; due to expansion and contraction of copper pipe joints and pipes. The coefficient is different. After high-temperature operation, the problem of dripping at the joints will be very serious, which will affect the promotion of floor heating, and it will easily result in the loss of user's property.

In practice, we have solved the problem of low-temperature (55°C) operation of floor heating, that is, installing a hot and cold water automatic temperature mixing valve in front of the floor heating water supply manifold. The thermostatic mixing valve has two inlets for cold water and hot water, and one inlet for mixing water. At the outlet of the mixing water of the thermostatic mixing valve, a thermo-element is installed. The physical characteristics of the temperature-sensing element are used to push the valve inside the valve. The core moves, plugs or opens cold and hot water inlets. When the cold water is blocked, the hot water is turned on. When the temperature control knob is set to a certain temperature, no matter how the cold or hot water inlet temperature and pressure change, The proportion of cold and hot water in the inlet and outlet also changes automatically, so that the outlet temperature is always constant, the positive and negative values ​​are maintained between plus and minus 2 °C, the thermostat can be specified within the temperature range 35 °C -65 °C Setting, thermostatic mixing valve will automatically adjust the set outlet temperature. Note: The temperature of the water supply pipe is 60°C-80°C-95°C. The mixed water temperature is 55°C. The check valve in the return pipe in the figure is to ensure that the circulator pump only extracts geothermal water, if the return water temperature is higher than the mixture Outlet temperature, automatic temperature mixing valve will automatically close the hot water inlet, the geothermal system automatically cycles, so that the return temperature drops, in a certain proportion of high-temperature water, energy saving effect is obvious.