Under Floor Heating

UNDER FLOOR HEATING TECHNOLOGY

Ordre of EngineersTripoli - Lebanon

Eng. Wael Zmerly 02-11-2007

ZMERLY & CO SARL.2Order of Engineers – Tripoli - Lebanon

Eng. Wael Zmerly - 2007Under Floor Heating Technology

WHAT IS “FLOOR HEATING”

TO USE THE FLOOR AS A HEAT EMISSION SURFACE



HISTORICAL BACKGROUND

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

2000 years ago




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.

1900




1945 TO 1950In 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)

The boiler temperaturewas 70ºC to 80ºC. The reason why the floor temperature was 34ºC to 40ºC. Which caused also some health problems.

40ºC

No use of cement slab, High thermal inertia.



THE NEW SYSTEMS

FROM 1970s3 New values were added:

Low surface temperature (28 - 29ºC).

Low thermal inertia of the floor slab.

29ºC

• More insulation, Low heat losses.

• Use of Floating floors.

Uniform heat distribution. • Plastic pipes, small pitches.



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.



HEATING OUTPUT RELATED TO LIMITED AREA.

RELATIVLY HIGH THERMAL INERTIA.

INCONVIENIENTS



HEAT AND COMFORT

Hottest part of the room is at ceiling level.Room temperature setting at 21ºC.Cold feet due to cooler convective air current.

RADIATOR HEATING 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.



16 20 24ºC

170cm

270cm

10cm

HEAT REPARTITION

16 20 24

Floor heating radiant panel

Ceiling heating

Radiators (external walls)

Radiators (internal walls)

Warm air

Warm air

Floor heating

Ceiling heating

Radiators ext.

Radiators int.

Thermal comfort Ideal curve



APPLICATIONS

RESIDENTIAL. OFFICES.

INDUSTRIAL.



PANEL CONTAINEMENT STRUCTURES

Thermal Concrete

Insulation

Floor Slab

Tiles

Protective diaphragm

Acrylic adhesive

Acrylic grouting

Panel Pipes

Insulation strip

Skirting board

2.0cm

2.5cm

4.0cm

1.5cm



LAYOUT

Loops

Distribution manifold



LAYOUT



LOOP CONFIGURATIONS

variation

SINGLE SERPENTINE



LOOP CONFIGURATIONS

Floor temperatureVariation

PARALLEL SUPPLY AND RETURN – COUNTERFLOW TYPE



LOOP CONFIGURATIONS

Floor temperatureVariation

PARALLEL SUPPLY AND RETURN – SPIRAL TYPE



LOOP CONFIGURATIONS



MATERIALS



PIPES

PEX with oxygen barrier

PEX – ALU - PEX

PIPE REEL



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.



MANIFOLDS



PERIFERAL INSULATION STRIP



INSULATION BOARD



EXPASION JOINTS



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



CONCRETE COMPOSITION

• 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

1m³of concrete contain



CALCULATION PARAMETERS

Ambient air temperature

Outer diameter of pipe

Internal diameter of pipe

Thermal conductivity of pipe

Flow temperature of waterCenter to center distance

Thermal resistance of the floor

Thermal conductivity of slab

Thickness of slab above pipe

Panel surface

Thermal resistance below panel

Underneath room temperature



REQUIRMENTS

CENTER TO CENTER DISTANCEThe 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

MAXIMUM DESIGN WATER TEMPERATURE

• 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.

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

SURFACE TEMPERATURE OF THE FLOOR

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.



REQUIRMENTS

TEMPERATURE DIFFERENCE OF HEATING FLUID

It is advisable not to be too high in order:• not to over-reduce the average temperature of the 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

PANEL FLOWConsidering 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

HEAD REQUIRED It is advisable that the difference between the preset head and that should be at least 200 ÷ 300 mm w.g.

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



HEAT OUTPUT

tp = surface temperature of floor, °Cta = ambient temperature, °Cq = 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.



CONTROL SYSTEM



BOILER ROOM

Mixing Valve



BETONKOERNAKTIVERUNG



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.



CEILING HEATING



ELECTRICAL FLOOR HEATING

Under Floor Heating

Technology

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