Floor heating technology and regulatory terms

Floor heating is one of the heating methods most consistent with the human body's heating physiological needs characteristics. The indoor temperature is uniform, and the room temperature gradually decreases from the bottom up, giving people a good feeling of cooling their feet and head, and better solve the "cold from the foot of life." The difficulty of working in this environment is conducive to improving work efficiency. Due to the low surface temperature of radiation, dust and bacteria are not easy to float, or odor is generated due to sublimation, and it is not easy to cause contaminated indoor air and indoor cleanliness. Living or working in a heated room feels comfortable, hygienic, and has a health-care effect. In general, the advantages of comfort, hygiene, space-free, energy-efficient, thermal stability, long service life, and low operating cost have been widely used at home and abroad, especially in Xinjiang since 2004. Gradually began to replace the hot water radiator, floor heating design instructions and the choice of materials involved in many aspects of knowledge, require professionals to clarify, so no detailed discussion here, only the outline of the implementation of the work.
1. Terms
1.1 File up layer
Structures placed around and above the heating pipes to protect the heating pipes and make the ground temperature uniform.
1.2 Heat insulating layer
The structural layer laid under the filler layer and along the perimeter of the perimeter wall serves to reduce ineffective heat loss.
1.3 Expansion seam
In the filling layer in place, to prevent cracking and damage to the ground due to cold heat expansion.
1.4 Tube clamps
When using a method of fixing the heating tube directly on the composite thermal insulation layer, the plastic staples used.
1.5 Wire metting
Another type of low carbon steel wire textile component used for the fixed heating pipe method is laid on the surface of the heat insulating layer.
1.6 Belting
Fix the heating tube to the plastic band on the wire mesh.
2 Design Notes <for reference only>
2.1 design parameters brief design category residential design value room temperature °C18-22
Incoming and returning water temperature difference °C8-11
Floor surface temperature °C23-29
Heat output (w/m2)47-125
Flow rate (l/s) 0.02-0.15
Pressure drop (K/Pa) 20-40
Loop length (m) 60-120
Tube size (diameter mm) 16, 20, 25
Tube spacing (mm) 150-400
2.2 Example of Design Parameters <Watung Town Government>
2.2.1 Building area: ___m2
2.2.2 heating outdoor design temperature: -22 °C
2.2.3 Heating Interior Design Temperature: 18°C
2.2.4 Floor Heating Water Supply Temperature: 55°C
2.2.5 floor heating backwater temperature; 45 °C
2.3 warm surface temperature design
2.3.1 The average surface temperature of the laying floor of heating pipes Tep can be calculated according to the following approximate formula:
TPE=tn+9(q/100 0.909)
Where: q effective floor area heat dissipation (W/mm)
Tn indoor temperature (°C)
2.3.2 The average surface temperature Tep of the laying floor of heating pipes shall not exceed the following limits:
2.3.2.1 Persons staying in the area for a long time at 28°C (preferably 24-26°C;
2.3.2.2 Short-term residence of personnel at 32°C (preferably 28-300°C;
2.3.2.3 No personnel stay area 42 °C (preferably 35--40 °C;
Note: Limits are defined as the average surface temperature that is reached only for the shortest time in the coldest days.
3 Materials Selection <for reference only>
3.1 The choice of heating coil should be based on the temperature of the system's heat medium, the use of conditional levels, design work pressure, system water quality requirements, and the physical and mechanical properties of the pipe and other factors. In the actual construction process, the most widely used is: cross-linked polyethylene (PE-X) pipe, 20mm * 2.0mm.
3.1.1 The following is a comparison of the physical and mechanical properties of each pipe used for floor heating.
Item Unit Specification Cross-linked Polyethylene Pipe (PEX) Crosslinked Aluminum-Plastic Composite Pipe (XPAP) Polybutylene (PB) Heat-Reinforced Polyethylene (PE-RT)
Density g/cm 3≥0.93----≥0.92 0.933
Longitudinal length shrinkage% ≤ 3---- ≤ 3 ≤ 3
Tensile strength at yield (23+1 0) Mpa 16≥23 17 16.5
Elongation at break (23+1 0)%≥400≥350≥125≥800
Thermal conductivity W/(mk) 0.41 0.45 0.22 0.4
Linear expansion coefficient Mm/(mk) 0.200 0.025 0.130 1.95
3.1.2 The commonly used cross-linked polyethylene pipes are described in detail.
Cross-linked polyethylene pipe (PE-X): (Cross linked polyethylene pipe)
The polyethylene or ethylene copolymer with a density of ≥ 0.94 g/cm3 is added with an appropriate amount of auxiliary agent to chemically or physically crosslink its linear macromolecules into a three-dimensional network of macromolecular structures. The finished pipe is usually marked with PE-X. Its long-term use at 0 °C ~ 95 °C and 0.6MPa pressure, life up to 50 years. Cross-linked polyethylene (PEX) pipe is suitable for low temperature floor radiation system, its compressive strength (more than 8 kilograms) than PP-R and PE-AL-PE pipe, a single structure, thermal expansion coefficient and concrete thermal expansion coefficient is close. The application of this pipe can greatly reduce the probability of cracking in pipes and concrete.
3.2 The choice of water separator
3.2.1 The manifold installation should be copper or brass.
3.2.2 The exhaust valve is provided for the return water.
3.2.3 The “Y” type filter should be set at the front end of the water supply.
3.2.4 Valves shall be provided for each branch of the water supply diversion pipe to regulate the amount of water.
3.3 Selection of heat-insulating panels It is advisable to use HDPE foam (polyethylene foam).
3.4 The choice of materials must have a factory certificate and inspection report of the relevant department.
4 The structure design of floor heating floor design, different areas, and different design units vary in the schemes adopted. Now only the situation of the internship site is described.
4.1 Example 1: Warm Section of Building Materials Market
a.C20 fine stone concrete filling layer 60mm
b.PEX tube D=20
c. Steel wire mesh D=2, @=100*100
d. Heat insulation mat (with aluminum foil) 3mm thick
e. Waterproof layer (bathroom design)
f.Structural layer