In article ,
writes:
I remember an 'off peak' heatbank/storage heater at work about 30 years ago.
It comprised a large tank insulated with about 30 cm of asbestos. It was
heated by 'electrode' boilers, where the element was the water circulating
through the tank (and central heating radiators as well, but they may have
been on a secondary circulation). The instructions included adding salt to
the water if the 'electrodes' didn't draw enough power (to earth, the boiler
casing) with the electrode shields fully retracted. You added salt until the
boiler sucked enough power from the mains to give full power with 80% of the
electrodes exposed. A servo system (which didn't work, automagically adjusted
the electrode shields to achieve this.

The system was installed in the 1930s I wonder what current HSE peeps would
think of it.

Such systems are still used for electric water heaters.
Look up elecrode boilers on google. They tend to need
3-phase supplies which rules them out for most of the
UK domestic market, but they are used both domestically
and commercially elsewhere.

--
Andrew Gabriel