Useful Technical Data

  

Contents:
Properties of Water
Graph of pressure losses vs. flow rates

 

Properties of Water:

Chemical Formula:  H2O
Water molecules are made up of two atoms of Hydrogen joined to one atom of Oxygen.

Melting / Freezing Temperature:  0C

Boiling Temperature:  100C

Density:  1000 kg / m3  or   1 kg / litre
This is a measure of the mass (weight) of a set volume of water.

Specific Heat Capacity:  4200 J / kg / C
This is a measure of the amount of energy, measured in Joules, required to heat water. 
1 Watt = 1 Joule of energy per second
1 kW = 1000 Joules of energy per second

Often, energy is measured in kWhs
1 kWh = 3,600,000 Joules (= 3.6 MJ,  1 MJ = 1 million Joules)

Example: To calculate the amount of energy required to heat 100 litres of water through 10C:

Energy = Mass of water (kg)  x  Specific Heat Capacity  x  Change in Temperature
> Energy = 100 x 4200 x 10  =  4200000 Joules  or  4.2 MJ

From this we can calculate the time it would take a 3kW heater to heat the water:

1 Watt = 1 Joule per second
> 3kW = 3000 Joules per second

Time taken (Seconds) = Energy Required (Joules) / Energy Input (Watts)
> Time = 4200000 / 3000  =  1400 seconds  =  23.3 minutes

Note: It is very important to work in the correct units when making energy calculations.

 


Kv Pressure Loss Graph:

 

Pressure Losses through common Thermostatic Valves:

 

Pump Curves for standard domestic circulator 5m head:

 






 

Conductivity and Density

Conductivity (k) is the ability to conduct heat through a material. 

Heat Flow in Watts = (thermal conductivity) x (area / length) x (temperature difference)

Group Material Specific mass (kg/m3) Thermal conductivity (W/mK)
Dry Wet
Metal Aluminium 2800 204 204
Copper 9000 372 372
Lead 12250 35 35
Steel, Iron 7800 52 52
Zinc 7200 110 110
Natural stone Basalt, Granite 3000 3.5 3.5
Bluestone, Marble 2700 2.5 2.5
Sandstone 2600 1.6 1.6
Masonry Brick 1600-1900 0.6-0.7 0.9-1.2
Sand-lime brick 1900 0.9 1.4
  1000-1400 0.5-0.7  
Concrete Gravel concrete 2300-2500 2.0 2.0
Light concrete  1600-1900 0.7-0.9 1.2-1.4
1000-1300 0.35-0.5 0.5-0.8
300-700 0.12-0.23  
Pumice powder concrete  1000-1400 0.35-0.5 0.5-0.95
700-1000 0.23-0.35  
Isolation concrete 300-700 0.12-0.23  
Cellular concrete  1000-1300 0.35-0.5 0.7-1.2
400-700 0.17-0.23  
Slag concrete  1600-1900 0.45-0.70 0.7-1.0
1000-1300 0.23-0.30 0.35-0.5
Inorganic Asbestos cement 1600-1900 0.35-0.7 0.9-1.2
Gypsum board 800-1400 0.23-0.45  
Gypsum cardboard 900 0.20  
Glass 2500 0.8 0.8
Foam glass 150 0.04  
Rock wool 35-200 0.04  
Tiles 2000 1.2 1.2
Plasters Cement 1900 0.9 1.5
Lime 1600 0.7 0.8
Gypsum 1300 0.5 0.8
Organic Cork (expanded) 100-200 0.04-0.0045  
Linoleum 1200 0.17  
Rubber 1200-1500 0.17-0.3  
Fibre board 200-400 0.08-0.12 0.09-0.17
Wood Hardwood 800 0.17 0.23
Softwood 550 0.14 0.17
Plywood 700 0.17 0.23
Hard-board 1000 0.3  
Soft-board 300 0.08  
Chipboard 500-1000 0.1-0.3  
Wood chipboard 350-700 0.1-0.2  
Synthetics Polyester (GPV) 1200 0.17  
Polyethene, Polypropene 930 0.17  
Polyvinyl chloride 1400 0.17  
Synthetic foam Polystyrene foam, exp. (PS) 10-40 0.035  
Ditto, extruded 30-40 0.03  
Polyurethane foam (PUR) 30-150 0.025-0.035  
Phenol acid hard foam 25-200 0.035  
PVC-foam 20-50 0.035  
Cavity isolation Cavity wall isolation 20-100 0.05  
Bituminous materials Asphalt 2100 0.7  
Bitumen 1050 0.2  
Water Water 1000 0.58  
Ice 900 2.2  
Snow, fresh 80-200 0.1-0.2  
Snow, old 200-800 0.5-1.8  
Air Air 1.2 0.023  
Soil Woodland soil 1450 0.8  
Clay with sand 1780 0.9  
Damp sandy soil 1700 2.0  
Soil (dry) 1600 0.3  
Floor covering Floor tiles 2000 1.5  
Parquet 800 0.17-0.27  
Nylon felt carpet 0.05    
Carpet (with foam rubber) 0.09    
Cork 200 0.06-0.07  
Wool 400 0.07  

 

 

 

 

 

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