Off-peak circuits for storage heaters

[Graham Nye]

Economy 7 has a single dual-rate meter connected to a single set of electrical wiring in the property. (I had this in the 1980s.) To benefit from the cheaper night rate your storage heaters will need a timer somewhere so they are only switched on during the night rate period.

Back in the 1960s I vaguely remember my (English) grandparents had a different system then known as a white meter which had a second (white!) meter for night rate heating. This was in addition to the standard day rate meter which was in the usual black Bakelite case.

The white meter came with a contactor feeding a separate set of electrical wiring which was only connected to devices on the night rate. Storage radiators would be connected to this wiring. They didn't need their own timers as the white meter/contactor would only switch them on during the night rate period.

There is a diagram of the two systems at this link (scroll down):

If your hall wiring is old enough it may use this system.

Note this original white meter system with separate wiring has disappeared in favour of Economy 7, which is cheaper to install. In Scotland Economy 7 is known as White Meter and this usage has now spread south of the border. As the change- over to E7 occurred pre-WWW it's hard to find links to the original white meter system. A lot of modern links to "white meter" are just synonyms for E7.

[Max Demian]

The flat I used to live in (1998-2015) had Economy 7 and the (spring reserve) timeswitch *did* switch the storage heater and off-peak immersion heater as well as changing the rates.

Before 1998 I was at a place with an earlier system which had a booster period in early afternoon for the storage heaters and hot water which were *only* switched by the timeswitch. Other circuits were always charged at the full rate. I don't know what the tariff was called.

[Tim Streater]

I suspect that is exactly our situation and that timers will be required. At least the timers will be mains powered but will need resetting after any power outage.

Another advantage for domestic users of E7 over the "white meter" scenario, is that with the latter, you'd have to connect your (say) washing machine to the "white" circuit in order to have it run overnight. Which would mean (a) that you couldn't run the washing machine during the day and that (b) devices such as washing mashines or dish washers that have a "turn me on now but delay for

3 hours before starting" couldn't be set like that. Well, I suppose they could if the timer was clockwork but manufacturers wouldn't like that.