£400 Gas and Water Bill - Climate Change Levy and VAT

Ectophile

I've done a similar calculation to QrizB and come up with a similar figure.

The specific heat capacity of water is 4.187 kJ/kg K

1 m³ of water is 1000 kg

So the heat capacity of water is also 4187 kJ/m³ K

4187 kJ is 1.163 kWh

So the heat capacity of water is 1.163 kWh/m³ K

Assume we want to heat the water by about 50 K (thats the same as 50 °C)

Heating 1 m³ of water by that much would take 58.15 kWh

Heating 6.52 m³ of water would take 377.9 kWh

That's nowhere near 1797 kWh.

Something is wrong with your bill.

markin

Could they have mixed the Heating and hot water up? £240 for the heating and £100 for DHW heating would make more sense would it not.

Also could the boiler be old and only be 50-60% efficient?

Scot_39

Assuming it's a central tank, the water will be being heated and reheated against tank and pipework losses to ambient in the boiler room etc.

Edit 2 And older domstic boilers with permanent pilot lights also had non trivial costs - estimates ranging from 500-2500 kWh annually.  Significant compared to Ofgem Tdcv level.


These losses can be non trivial for a large boiler but small actual flows.

(My small domestic in house airing cupboard tank - solid foam insulated only - and outflow pipe will "lose" maybe a couple of kWh a day in winter even with no flow when het 3x daily by my e10 system.  A more modern tank would be better.  Thought about putting a second lagging jacket on in past - but the lost heat heats the space and keeps linens fresh etc.)

With such losses it's never just a straight volume to weight for a storage tank. 

Edit : and combined with pipe losss etc why some revert to boiling kettles rather than heating tanks - and others alllow  tanks to cool over 2-3 days then reheat as water gets too cold.

And above physics calcs ignores the efficiency of the gas boiler as well.  At best you might average 90% on a small modern domestic combi heat on demand system - a few decades ago that might have been 60-70% for non condensing boiler and tank setup.


But the over 2:1 ratio across the months does look extreme.


You could ask the energy supplier if they think that over 2:1 ratio change in costs reasonable or normal.

Or ask them / your landlord expkicitly if same trend observed last year to see if truly seasonal.

It could be one or more premises arent now being metered correctly to take share total costs or something else going wrong.

Edit 2  Or one or more premisses significantly changed usage - meaning forinstance could now be carrying a far bigger share of losses.

PS If your landlord is purely passing on costs from third party with accurate figures as theirs - landlord resell profit comments above don't apply.