15. 1. 1 Characteristics of low-temperature hot water floor heating
The characteristics of low-temperature hot water floor heating are:
(1) The feeling of warmth and comfort first comes from people's feet. The wonderful feeling of walking barefoot on the floor in late winter is one of the benefits that low-temperature floor radiant heating system can bring you;
(2) Uniform thermal radiation can avoid dust generated by convection of hot and cold air and make your living environment healthier;
(3) Lower indoor temperature can reduce the evaporation of indoor air moisture and make your living environment more comfortable;
(4) Leaving out the traditional radiator will make your room more tidy and beautiful [27].
15. 1.2 characteristics of electric heating and radiation heating
Electric floor heating means laying pipes under indoor floors (such as cement floors, tile floors and wood floors), heating and cooling the floors to a certain temperature through the special two-way circulation mode of the heat body in the pipes, and then radiating the heat evenly from the floors to the rooms. At the same time, under the action of the specific gravity difference between hot and cold air, the natural convection phenomenon of air is generated, thus creating an ideal indoor hot microclimate with temperature distribution and making the indoor environment reach the most comfortable state of human senses. Compared with traditional heating methods, electric floor heating has the following advantages:
① Electric floor heating is efficient and energy-saving. The heat of electrothermal radiation heating is concentrated at the height beneficial to human body, which is higher than that of convection heating (if the parameter is designed and used at 16 degrees Celsius, the heating effect can reach 20 degrees Celsius); When the heat medium is transported at low temperature, the heat loss in the whole transportation process is small, saving about 20% energy compared with the traditional air conditioner and more than 30% energy compared with the traditional radiator.
Electric floor heating comfortable health care
Low-temperature electric floor heating, the indoor surface temperature is uniform, and the room temperature gradually decreases from bottom to top, giving people a good feeling of warm feet and cool head, thus forming a thermal microenvironment that truly meets the requirements of the human body.
The electric floor heating project has good thermal stability.
Because of the large heat storage capacity of the bottom layer and the heat storage layer, the indoor temperature changes slowly and has good thermal stability under the condition of intermittent heating.
② Electric floor heating saves space. The concealed installation of electric heating system cancels the traditional indoor radiator and its branch pipes, which is convenient for decoration and furniture layout and increases the use area.
Solve the problem of household measurement
The two pipes of electric floor heating are installed in parallel, and each household controls the circulating water separately, which solves the problem that the heating system cannot be correctly metered and charged by households for many years.
Room temperature adjustment is convenient.
Each loop in the electric water separator is equipped with its own control valve, and each household adjusts the flow according to its own room temperature, so as to save energy and cost to the maximum extent.
③ Electric floor heating and environmental sanitation. The surface temperature of electric heating is low, which will not lead to the rapid flow of indoor air and dust flying, reduce the evaporation of water in the air, reduce the pollution to walls, articles and air, eliminate the odor volatilized from the dust collection surface of hot equipment and pipelines, and improve the sanitary conditions.
(4) The insulation layer is laid on the ground of the soundproof floor, and the soundproof effect is remarkable.
⑤ The electric heating system has long service life and is maintenance-free.
⑥ Plastic coil has long service life, and the system adopts coil loop technology. There is no joint in concealed pipeline system, which is not conducive to leakage and maintenance-free [28].
Economic cost analysis of 15.2 low temperature radiation
The floor of low-temperature floor radiant heating residence consists of the following three parts: load distribution layer, plastic pipe layer and heat insulation and moisture insulation layer. Among them, the load distribution layer is 40 mm thick fine stone concrete, the plastic pipe layer is crosslinked polyethylene pipe, and the thermal insulation and moisture insulation layer is 25 mm thick benzene board and aluminum foil. The cost price of each part and its construction cost are listed in table 15- 1.
Table 15- 1 lowest cost composition
Project Material Cost (RMB/m2) Total (RMB/m2)
Load distribution layer fine stone concrete 40
100
Plastic pipe layer crosslinked polyethylene 30
Thermal insulation and moisture insulation layer benzene board+aluminum foil 15
Construction cost 15
In order to better compare with the common radiator system, the residential building is still taken as an example, and the system is a common radiator heating system, and the scheme is calculated. See table 15-2 for the results, and compare the economic indicators of the two heat suppliers side by side. Compared with the traditional heating system with temperature control valve, the floor radiant heating system increases the cost per unit building area;
100-4815+18-5615-1918 =-6.8 yuan per square meter.
Compared with the traditional heating system without temperature control valve, the floor radiant heating system increases the cost per unit building area:
100-35+18-5615-1918 = 6.7 yuan/m2.
From the above comparison results, it can be seen that although the cost of floor radiant heating system is high, and the civil engineering cost is increased due to the increase of floor height, the decoration cost of radiator is reduced, and the occupied area of radiator is converted into effective use area. If the floor area can be sold as building area, the investment of floor radiant heating system can be basically the same as that of traditional heating. It is true that some factors in the above comparison are difficult to determine in practice, such as whether the saved radiator area can be sold separately, and whether the radiator decoration cost can be counted as the saved construction cost. But from the overall investment benefit and the actual use benefit of buyers, this analysis is feasible.
Table 15-2 List of economic indicators of two schemes [29]
Project name economic index value
The total construction area is 18000m2.
Ground floor 18.
The number of radiator groups is 5 10.
The high added value of each floor of floor heating is 10㎝.
Increase the storey height and increase the cost per square meter 18 yuan.
The price of commercial housing is 5000 yuan per square meter.
Traditional heating cost per square meter 35 yuan
Crosslinked pipe floor heating per square meter 100 yuan.
The cost of traditional heating with temperature control valve is 48.5 yuan per square meter.
Save the cost of radiator cover (5 10×700 yuan) by 357,000 yuan.
Converted into the original construction area of 6,543,800 yuan+0,980 yuan per square meter.
Increase the usable area (5 10× 0.3m2) 153m2.
The converted building area is (153x1.33m2) 203.5m2.
The commodity value in this area (203.5×5000 yuan) is 10 17500 yuan.
The original area per square meter increased by 56.5 yuan.
Water pipes and pipes include PB (polybutylene pipe ISO/DISI5876), PEX (crosslinked polyethylene pipe ISO/DISI5875) and PP-R (random polypropylene pipe ISO/DISI5874). , suitable for geothermal engineering. The heating water temperature should be controlled at 50 degrees, and sometimes it is better to reach 60 degrees. However, due to the different water temperature in the structural layer of geothermal buildings, the heat dissipation is also different.