Conserve heat and use the best electricity tariff

The importance of insulation and how to optimise the use of cheap night rate electricity tariffs.

Most systems use an electric immersion heater fitted into an insulated tank. It’s a simple system, very reliable and very efficient in terms of energy transfer. However electricity is an expensive primary fuel - notably the case with on-peak electricity - so it’s important to both conserve the heat and to use the cheapest tariff rate electricity available.

The water heater should be well insulated and heat losses especially from lids and pipes minimised.  All too often lids are badly fitting and can also be uninsulated leading to a high heat loss from this area.

Water heating systems can take advantage of lower rate electricity tariffs by having the heating element switch on during these periods. Heating of water in this way uses electricity at a cost 30% lower than high rate electricity.

To maximise advantage of off peak energy you must have:

• The right tariff
• Adequate hot water storage so you don’t have to heat extra water on higher rate
• A timeswitch accurately synchronised with the timings of low rate electricity

If you have a multi rate tariff, it’s worth checking that both the electricity company’s meter timeswitch and your own water heater timeswitch are synchronised.

The meter timeswitch will be located next to your main electricity meter and will have a clockface style dial with start and stop set points. Check that the “time now” shown on this dial is the actual time. If it is one hour out this is possibly due to GMT / BST. If there is no clockface timer then you probably have a remote teleswitch which can be identified as it will have a small “stubby” aerial. These update automatically so it is ok to assume it is correct.

A 1-hour difference on a 3 kW heater will cost about £55 per year in higher bills.