Floor Heating

Ordre of Engineers Tripoli - Lebanon

UNDER FLOOR HEATING TECHNOLOGY

Eng. Wael Zmerly 02-11-2007

WWW.ZMERLY.COM

WHAT IS “FLOOR HEATING”

TO USE THE FLOOR AS A HEAT EMISSION SURFACE Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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HISTORICAL BACKGROUND

2000 years ago

Heating systems inspired by this idea were built by the Chinese, Egyptians and Romans.

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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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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.

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THE NEW SYSTEMS

FROM 1970s • Use of Floating floors.

3 New values were added:

• More insulation, Low heat losses.

Low thermal inertia of the floor slab.

Low surface temperature (28 - 29ºC).

Uniform heat distribution.

• Plastic pipes, small pitches.

29ºC

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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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INCONVIENIENTS

HEATING OUTPUT RELATED TO LIMITED AREA.

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RELATIVLY HIGH THERMAL INERTIA.

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HEAT AND COMFORT

RADIATOR HEATING Hottest part of the room is at ceiling level.

Room temperature setting at 21ºC. Cold feet due to cooler convective air current.

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FLOOR HEATING Coolest part of the room is at ceiling level.

Room temperature setting below 21ºC (19).

No draught.

No cold feet.

Less dust which can settle on walls, furniture and curtains.

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HEAT REPARTITION 270cm

170cm

Floor heating Ceiling heating Radiators ext.

Radiators int.

Warm air 10cm

ºC

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20

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Thermal comfort Ideal curve Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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20

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Warm air Radiators Radiators Floor heating Ceiling (external (internal walls) walls) radiant panel heating 10

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APPLICATIONS RESIDENTIAL.

OFFICES.

INDUSTRIAL.

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PANEL CONTAINEMENT STRUCTURES

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LAYOUT Distribution manifold

Loops

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LAYOUT

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LOOP CONFIGURATIONS

variation

SINGLE SERPENTINE Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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LOOP CONFIGURATIONS

Floor temperature Variation

PARALLEL SUPPLY AND RETURN – COUNTERFLOW TYPE Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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LOOP CONFIGURATIONS

Floor temperature Variation

PARALLEL SUPPLY AND RETURN – SPIRAL TYPE Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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LOOP CONFIGURATIONS

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MATERIALS

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PIPES PEX – ALU - PEX

PEX with oxygen barrier

PIPE REEL Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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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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MANIFOLDS

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PERIFERAL INSULATION STRIP

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INSULATION BOARD

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INSULATION BOARD

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INSULATION BOARD

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EXPASION JOINTS

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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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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 Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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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 Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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REQUIRMENTS CENTER TO CENTER DISTANCE

MAXIMUM DESIGN WATER TEMPERATURE

HEAT OUTPUT REQUIRED

SURFACE TEMPERATURE OF THE FLOOR

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The most frequently used grids are as follows: • 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; • 40 a 45°C with district heating, condensing boilers, heat pumps; • 32 a 38°C with solar panels.

Two aspects in consideration : • the lack of heat loss through the floors, • the heat contribution of any panels located on the floor above.

To avoid uncomfortable physiological conditions, the 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.

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REQUIRMENTS It is advisable not to be too high in order: TEMPERATURE DIFFERENCE OF • not to over-reduce the average temperature of the fluid, and thus the heat output of the panel; HEATING FLUID • to avoid surface temperatures which differ too much from each other, • Usually it is used below 8 ÷ 10°C PANEL FLOW

HEAD REQUIRED

LENGTH OF THE PANEL

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Considering that the maximum flow of a panel is on 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 and that should be at least 200 ÷ 300 mm w.g.

In domestic applications, it is advisable not to go beyond the commercial lengths of pipe rolls (120 ÷ 150 metres)

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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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CONTROL SYSTEM

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CONTROL SYSTEM

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BOILER ROOM

Mixing Valve Order of Engineers – Tripoli - Lebanon ZMERLY & CO SARL.

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HEAT ACTIVATED BUILDING MASS

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WALL HEATING

Radiant wall heating is one of the most comfortable form of heating available.

Water circulating at 30-40ÂşC in pipes built into the wall provides gentle but highly efficient radiant heat.

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CEILING HEATING

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ELECTRICAL FLOOR HEATING

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