For those unfamiliar with the term 'Electric Wet Heating' it simply means an electrically powered system which pumps hot water round traditional radiators to heat the house.
There are several electric boilers on the market, but they work in two different ways:
The Thermaflow Thermal store boiler has been designed and manufactured to be most efficient on the Scottish Power Economy 2000 tariff. This tariff provides 18 hours of electricity supply at half price, which is the most of all the electricity suppliers.
The shut down periods are:
If the boiler is used to a maximum (heating & hot water) for a maximum of 200 days throughout the year - consuming 9kw/hr and hot water only for the remaining 165 days - consuming 3kw/hr, the total annual consumption would be 14400 kw/hr.
The off peak electricity rate is around 6.4 pence per kw/hr from Scottish Power as at 27th October 2009 (check with supplier for current rate) N.B Scottish Power also add a daily standing charge of 19 pence.
(cost = electricity used x rate)
Peak rate electricity used 0kw/hr
Off peak electricity used 14400kw/hr
Cost of electricity used £1054.31
(Based on a 210 litre, 9KW unit)
Flow type Boiler using Economy 10
'Flow' or 'Direct Acting' boilers can only operate on the Economy 10 tariff provided by such companies as Scottish Hydro Electric. This tariff can only provide a maximum of 10 hours electricity.
The shut down periods are:
If the boiler is used at maximum, (heating & hot water) for 200 days a year - consuming 9kw/hr and used for hot water only for the remaining 165 days - consuming 3kw/hr the total consumption would be 14400kw/hr.
This will have to be based on 7 hours of on-peak and 1 hour off peak per day in winter and 1 hour at peak rate per day in summer. The on peak rate as at 27th October 2009 was around 14.15 pence per kw/hr & the off peak was 7.07p kw/hr. (N.B check with supplier for current rate) N.B Scottish Hydro also add a daily standing charge of 26 pence
(cost= electricity used x rate)
Peak rate electricity used 9000kw/hr
Off peak electricity used 5400kw/hr
Cost of electricity used £1860.43
As demonstrated above the THERMAflow boiler can offer saving on electricity of over £806.12 over the year compared to using the equivalent direct acting boiler. (Based on electricity tariffs available in Scotland from October 2009).
This example is based on the requirements of a typical family home where hot water is required to heat 7 radiators and supply hot water to taps. During the winter, which we will assume covers half of the year (200 days), heating and hot water required for 8 hours each day. Between 7-11am and 5-9pm
During the summer (165 days) water is only required for 1 hour each day - between 5-6pm