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1. Ordre of Engineers
Tripoli - Lebanon
UNDER FLOOR HEATING
TECHNOLOGY
Eng. Wael Zmerly
02-11-2007

2. WHAT IS “FLOOR HEATING”
TO USE THE FLOOR AS A HEAT EMISSION SURFACE
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

3. HISTORICAL BACKGROUND
2000 years ago
Heating systems inspired by this idea were
built by the Chinese, Egyptians and Romans.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

4. HISTORICAL BACKGROUND
1900
At the start of this century floor heating appears in
its present form.
Hot water cycles inside a tube burred under ground.
In London in 1909, one of the Royal
palaces was heated with this new system.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

5. HISTORICAL BACKGROUND
1945 TO 1950
In Europe, from 1945 to 1950, over 100,000 homes were heated by this technique.
Very soon, however, it was noted that the equipment was
causing numerous physiological problems due to the
following facts:
Metallic pipes instead of plastic
(long distance between pipes)
No use of cement slab, High thermal
inertia.
40ºC
The boiler temperature
was 70ºC to 80ºC. The
reason why the floor
temperature was 34ºC to
40ºC. Which caused also
some health problems.
Order of Engineers – Tripoli - Lebanon 5 Under Floor Heating Technology
ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

6. THE NEW SYSTEMS
FROM 1970s
3 New values were added: • Use of Floating floors.
Low thermal inertia of the floor slab. • More insulation, Low heat losses.
Low surface temperature (28 - 29ºC).
Uniform heat distribution. • Plastic pipes, small pitches.
29ºC
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

7. ADVANTAGES
☺ Uniform heat distribution.
☺ Healthy conditions. Absence of air draughts.
☺ Safety.
☺ Space saving.
☺ Low noise
☺Temperature reduction from feet to head.
☺ Lack of dryness due to low temperatures.
☺ Friendly to the environment.
☺ Efficient. Low operating cost.
☺ Reduction of roof thermal loses.
☺ Short-term depreciation.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

8. INCONVIENIENTS
HEATING OUTPUT RELATED TO RELATIVLY HIGH THERMAL
LIMITED AREA. INERTIA.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

9. HEAT AND COMFORT
RADIATOR HEATING FLOOR HEATING
Hottest part of the room is at ceiling Coolest part of the room is at ceiling level.
level. Room temperature setting below 21ºC (19).
Room temperature setting at 21ºC. No draught.
Cold feet due to cooler convective air No cold feet.
current. Less dust which can settle on walls, furniture
and curtains.
Order of Engineers – Tripoli - Lebanon 9 Under Floor Heating Technology
ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

10. HEAT REPARTITION
270cm
170cm
Floor heating
Ceiling heating
Radiators ext.
Radiators int.
Warm air
10cm
ºC 16 20 24 16 20 24
Thermal comfort Warm air
Radiators
Radiators
Floor heating
Ceiling
Ideal curve (external walls)
(internal walls)
radiant panel
heating
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

11. APPLICATIONS
RESIDENTIAL.
OFFICES.
INDUSTRIAL.
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12. PANEL CONTAINEMENT STRUCTURES
Skirting board Acrylic Acrylic
adhesive Tiles grouting
Insulation Protective Panel
strip diaphragm Pipes
1.5cm
Thermal Concrete 4.0cm
2.5cm
Insulation 2.0cm
Floor Slab
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13. LAYOUT
Distribution
manifold
Loops
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14. LAYOUT
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15. LOOP CONFIGURATIONS
variation
SINGLE SERPENTINE
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16. LOOP CONFIGURATIONS
Floor temperature
Variation
PARALLEL SUPPLY AND RETURN – COUNTERFLOW TYPE
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17. LOOP CONFIGURATIONS
Floor temperature
Variation
PARALLEL SUPPLY AND RETURN – SPIRAL TYPE
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18. LOOP CONFIGURATIONS
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19. MATERIALS
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20. PIPES
PEX – ALU - PEX
PEX with oxygen barrier
PIPE REEL
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

21. MANIFOLDS
For correct operation and maintenance of the
system, manifolds must have:
•Main on/off valves,
•Panel on/off valves,
•Micrometric panel regulating valves,
•Automatic air vents,
•Drain cocks.
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22. MANIFOLDS
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23. PERIFERAL INSULATION STRIP
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24. INSULATION BOARD
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25. INSULATION BOARD
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26. INSULATION BOARD
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27. EXPASION JOINTS
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28. NETWORK TESTING
•For 30 min at 150% of working pressure
•For 90 min at double working pressure
•Installation test
•Same pressure during the pouring of thermal
concrete
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

29. CONCRETE COMPOSITION
1m³of concrete contain
• 0,8m³ river sand
• 0,4m³ gravel, 4 - 6mm grain size
• 350 kg cement
• 2,5 kg plasticizer
• 250 kg water
• 900 gr/m³ polypropylene fibers
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

30. CALCULATION PARAMETERS
Ambient air temperature
Outer diameter of pipe Thermal resistance of the floor
Internal diameter of pipe Thermal conductivity of slab
Thermal conductivity of pipe Thickness of slab above pipe
Flow temperature of water Panel surface
Center to center distance Thermal resistance below panel
Underneath room temperature
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

31. REQUIRMENTS
The most frequently used grids are as follows:
CENTER TO CENTER DISTANCE • 7,5 15,0 22,5 30,0 37,5
• 5,0 10,0 15,0 20,0 30,0
• 45 a 55°C with traditional boilers;
MAXIMUM DESIGN WATER • 40 a 45°C with district heating, condensing
TEMPERATURE boilers, heat pumps;
• 32 a 38°C with solar panels.
Two aspects in consideration :
HEAT OUTPUT REQUIRED • the lack of heat loss through the floors,
• the heat contribution of any panels located on
the floor above.
SURFACE TEMPERATURE OF To avoid uncomfortable physiological conditions, the
THE FLOOR surface temperature of the floor should be less than:
• 29°C in continuously occupied environments,
• 33°C in bathrooms, showers and swimming pools,
• 35°C in perimeter areas or rooms rarely used.
Order of Engineers – Tripoli - Lebanon 31 Under Floor Heating Technology
ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

32. REQUIRMENTS
It is advisable not to be too high in order:
TEMPERATURE DIFFERENCE OF • not to over-reduce the average temperature of the
HEATING FLUID fluid, and thus the heat output of the panel;
• to avoid surface temperatures which differ too much
from each other,
• Usually it is used below 8 ÷ 10°C
Considering that the maximum flow of a panel is on
PANEL FLOW average between:
•200 ÷ 220 l/h, for pipes with Di = 16 mm
•120 ÷ 130 l/h, for pipes with Di = 13 mm
It is advisable that the difference between the preset
HEAD REQUIRED
head and that should be at least 200 ÷ 300 mm w.g.
In domestic applications, it is advisable not to go
LENGTH OF THE PANEL
beyond the commercial lengths of pipe rolls (120 ÷
150 metres)
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

33. HEAT OUTPUT
tp = surface temperature of floor, °C
ta = ambient temperature, °C
q = specific heat output (upwards) of panel, W/m2
In particular (at ambient temperature = 20°C), the maximum specific output which can be
transferred by a panel is:
• qmax = 8,92 . ( 29 – 20 ) 1,1 = 100 W/m2 in continuously inhabited environments.
• qmax = 8,92 . ( 33 – 20 ) 1,1 = 150 W/m2 in bathrooms, showers and swimming pools.
• qmax = 8,92 . ( 35 – 20 ) 1,1 = 175 W/m2 in perimeter areas or rooms rarely used.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

34. CONTROL SYSTEM
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35. CONTROL SYSTEM
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36. BOILER ROOM
Mixing Valve
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37. BETONKOERNAKTIVERUNG
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38. WALL HEATING
Radiant wall heating is one of the most comfortable form of heating available.
Water circulating at 30-40ºC in pipes built into the wall provides gentle but
highly efficient radiant heat.
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007

39. CEILING HEATING
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40. ELECTRICAL FLOOR HEATING
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ZMERLY & CO SARL. Eng. Wael Zmerly - 2007