InLine Hot Water System is A-Rated

The figures for heating water with Logicor's InLine Hot Water System are taken from actual measurements on a real system taken using industry standard power analyser equipment (Precision Power Scope PX8000) from Yokogawa with an accuracy of 0.01%.

Our calculation method for the cost of heating bath water with an Electric Immersion Heater and Modern A-Rated Gas Heater is outlined below.

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Last calculations made 18 December 2015.

T1 = Temperature of cold water entering system in Kelvin (K)
T2 = Temperature of hot bath water in Kelvin (K)
V = Volume of bath water  (litres)
S = Specific heat capacity of water is  4.18 J/cm3/K
Be = Boiler efficiency (A-Rated is assumed 90%)
EJ = Energy required to heat water in Joules
EB= Energy required to heat water with boiler efficiency adjustment
C = Cost to heat one bath

• The assumed water temperature entering the heater is 10°C.
• The assumed water temperature leaving the heater into the bath is 40°C.
• Energy prices are taken from the Energy Saving Trust website based on the average rate for domestic households in England, Scotland & Wales, last checked February 2015.
• Source: www.energysavingtrust.org.uk/content/our-calculations
• Electricity average price (Standard Rate) : 14.05 pence / kWh
• Gas average price (Standard Rate) : 4.29 pence / kWh

(EJ) Energy required to heat the water in Joules is therefore :
EJ (in Joules) = S x (T2-T1) x V x 1000

Adjustment  to account for the boiler efficiency (EB in Joules) is therefore :
EB (in Joules) = EJ x  ((1 + (100-Be)) / 100)

To convert Joules to kWh (1 kWh = 3600000 Joules) is therefore :
EB (in kWh) = EB (in Joules) / 3600000

(C) The cost to heat one bath in kWh is therefore:
C = EB x Energy price per kWh