how much gas used to heat water for 10 min shower, Worcester Greenstar CDI CLASSIC 29

patwatt999

I was wondering if I am correct in calculating how much gas and the cost, is used for a 10 minute shower using water heated by my Greenstar CDI CLASSIC 29 combi and a Mira thermostatic shower

Will it be approx 4.8 kW (1/6 of 32 kW ) which at my gas price of of 3.802 pence per kilowatt will be just over 18 pence?

patwatt999

32 kW should be 29 kW

Rodders53

patwatt999 said:

32 kW should be 29 kW

Not according to the installation manual. https://www.worcester-bosch.co.uk/professional/support/literature/greenstar-cdi-classic-combi-installation-instructions

It is 30.9 kW max rated heat input for either DHW or CH on the 29 model.

BUT that can only be used to calculate the maximum likely cost, as the boiler may not need to run at full bore to heat the water being used throughout the mixer shower at some times of year.

QrizB

patwatt999 said:

Will it be approx 4.8 kWh (1/6 of 32 kW ) which at my gas price of of 3.802 pence per kilowatt-hour will be just over 18 pence?

Thats the maximum it will cost. 29kW is enough power to heat almost 14 litres of water a minute from 10C to 40C. If your shower uses less water than that, the boiler will use less gas.

Spies

I had a shower tonight but cost is mixed in with CH, it's somewhere <4kwh.