GB2179215A

GB2179215A - Electrical appliances for low tariff electricity

Info

Publication number: GB2179215A
Application number: GB08520061A
Authority: GB
Inventors: James Barrie Whitham
Original assignee: Frederick Greenwood & Sons Ltd
Current assignee: Frederick Greenwood & Sons Ltd
Priority date: 1985-08-09
Filing date: 1985-08-09
Publication date: 1987-02-25
Also published as: GB8520061D0

Abstract

A storage heater, or other electrical appliance, incorporates an electrically powered time switch which is arranged to switch on the appliance during a period of low tariff electricity. In order to ensure that in the event of a power failure which results in an incorrect setting of the timer, normal tariff electricity is not subsequently used because the timer thereafter switches on the appliance at the wrong time, it is arranged that failure of the supply results in the de-energisation of a latching relay, or equivalent switch-off device, which controls the power supply to the operative part of the appliance. Manual intervention is required to re-set the latching relay. An indication of the need to re-set the time switch is provided.

Description

SPECIFICATION Electrical appliances for low tariff electricity This invention relates to electrical appliances, primarily but not exclusively storage space heaters, for use with low tariff electricity.

As is weil known, there is in England and many other countries surplus electricity generating capacity at certain times, especially during the night.

The Electricity Boards have therefore encouraged the use of this surplus capacity by providing low tariff schemes for specific night time or off-peak usages of electricity.

In a house it has become increasingly popular to use such low tariff electricity for storage space heaters and for heating water by an immersion heater in a lagged hot-water cylinder. With such systems the electricity meter incorporates a time switch which switches between two registers which respectively record the normal tariff and the low tariff amounts of electricity consumed. Such electrical appliances are usuaily provided with their own supply circuits from the meter board, that is circuits independent of those which supply the 13 amp house sockets.

It has been recognised that there would be a demand for auxiliary storage heaters which could be placed in a room, such as a bathroom, which is not close to any existing storage heater circuit, but which could be operated from a convenient 13 amp outlet. Such an appliance, or its local supply lead, would need to incorporate a timer assembly to ensure that the appliance can only operate during the periods of low-tariff. Such timer assemblies are already used for use with immersion heaters but they are expensive. The main reason for their expense is that it is generally considered to be necessary for the timer assembly to include a reserve timing facility which ensures that in the event of a power cut the timer continues to operate, to ensure that the appliances continue to operate only within the low tariff period.

The Electricity Boards are particularly concerned that such timer assemblies incorporate the reserve timing facility to ensure that a user will not inadvertently operate such an appliance during the normal tariff period, since this would result in an increased bill for the customer, and this could seriously affect the publics acceptance of low-tariff electricity systems.

The timer assemblies currently used with immersion heaters are 'battery-backed' assemblies, termed 'quartz reserve clocks', that is they comprise a quartz clock with a reserve battery which is normally kept charged by the supply but in the event of a supply cut the battery is intended to provide sufficient power to keep the clock running for several hours if necessary. Such quartz reserve clocks are expensive such that an auxiliary storage heater for connection to an existing 13 amp outlet would be made relatively expensive if it were to require such a quartz reserve clock.

Also, some doubt has been expressed as to the ability of the batteries to operate satisfactorily on more than one occasion, when they may only be called upon to operate at periods of several years apart.

We have realised that a less costly solution to the problem would be, according to the invention, to provide the appliance with an associated timer but without the reserve timing facility, and to arrange that failure of the mains power results in a switching off of the appliance by a switch off device which requires manual operation to switch it on again.

It might be possible to reiy on the switching off of the appliance by the switch off device to provide an indication that the timer needs resetting, but a separate indication of the need to reset the timer will usually be preferred.

The separate indication means could be in any convenient form, such as an illuminated light, a flashing light, a mechanical flag or an audible warning.

The switch off device is preferably a latching relay but it may be an electronic equivalent. The indication means would then probably be operated by the relay.

The switch off device may be housed within the casing of the appliance or may be housed within the casing of the wall outlet unit, or may be an independent unit for mounting on the wall adjacent to the appliance or outlet.

Preferably the switch off device is arranged to be reset by a manually operable reset member, such as a push button, accessible on the outside of the appliance casing or on the outside of the independent unit or outlet. However, the reset member could be arranged to be operated automatically when the timer resetting operation is performed, for example by the opening of a cover on the timer Storage heaters normally incorporate a variable control thermostat to control the electrical input to the heating elements. The provision of a timer may enable such a variable control thermostat to be dispensed with.

1. An electrical appliance intended to be connected to an electrical supply which has a predetermined normal tariff period and a predetermined low tariff period, the appliance being provided with an associated electrically powered time switch, which is powered from said electrical supply, the time switch controlling the switching-on and switching-off of the appliance such that the time switch can be set, if desired, by the user such that the appliance is regularly switched on only during the low tariff period, and the appliance being provided with an associated supply failure detection means which is so arranged that in the event of a failure of said electrical supply the appliance is switched off by a switch-off means and a subsequent manual operation is required to switch the appliance on again.

2. An appliance as claimed in claim 1 provided with an indication means adapted to indicate the need to reset the time-switch following a failure of the electrical supply.

3. An appliance as claimed in claim 1 or claim 2 in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electrical appliances for low tariff electricity This invention relates to electrical appliances, primarily but not exclusively storage space heaters, for use with low tariff electricity. As is weil known, there is in England and many other countries surplus electricity generating capacity at certain times, especially during the night. The Electricity Boards have therefore encouraged the use of this surplus capacity by providing low tariff schemes for specific night time or off-peak usages of electricity. In a house it has become increasingly popular to use such low tariff electricity for storage space heaters and for heating water by an immersion heater in a lagged hot-water cylinder. With such systems the electricity meter incorporates a time switch which switches between two registers which respectively record the normal tariff and the low tariff amounts of electricity consumed. Such electrical appliances are usuaily provided with their own supply circuits from the meter board, that is circuits independent of those which supply the 13 amp house sockets. It has been recognised that there would be a demand for auxiliary storage heaters which could be placed in a room, such as a bathroom, which is not close to any existing storage heater circuit, but which could be operated from a convenient 13 amp outlet. Such an appliance, or its local supply lead, would need to incorporate a timer assembly to ensure that the appliance can only operate during the periods of low-tariff. Such timer assemblies are already used for use with immersion heaters but they are expensive. The main reason for their expense is that it is generally considered to be necessary for the timer assembly to include a reserve timing facility which ensures that in the event of a power cut the timer continues to operate, to ensure that the appliances continue to operate only within the low tariff period. The Electricity Boards are particularly concerned that such timer assemblies incorporate the reserve timing facility to ensure that a user will not inadvertently operate such an appliance during the normal tariff period, since this would result in an increased bill for the customer, and this could seriously affect the publics acceptance of low-tariff electricity systems. The timer assemblies currently used with immersion heaters are 'battery-backed' assemblies, termed 'quartz reserve clocks', that is they comprise a quartz clock with a reserve battery which is normally kept charged by the supply but in the event of a supply cut the battery is intended to provide sufficient power to keep the clock running for several hours if necessary. Such quartz reserve clocks are expensive such that an auxiliary storage heater for connection to an existing 13 amp outlet would be made relatively expensive if it were to require such a quartz reserve clock. Also, some doubt has been expressed as to the ability of the batteries to operate satisfactorily on more than one occasion, when they may only be called upon to operate at periods of several years apart. We have realised that a less costly solution to the problem would be, according to the invention, to provide the appliance with an associated timer but without the reserve timing facility, and to arrange that failure of the mains power results in a switching off of the appliance by a switch off device which requires manual operation to switch it on again. It might be possible to reiy on the switching off of the appliance by the switch off device to provide an indication that the timer needs resetting, but a separate indication of the need to reset the timer will usually be preferred. The separate indication means could be in any convenient form, such as an illuminated light, a flashing light, a mechanical flag or an audible warning. The switch off device is preferably a latching relay but it may be an electronic equivalent. The indication means would then probably be operated by the relay. The switch off device may be housed within the casing of the appliance or may be housed within the casing of the wall outlet unit, or may be an independent unit for mounting on the wall adjacent to the appliance or outlet. Preferably the switch off device is arranged to be reset by a manually operable reset member, such as a push button, accessible on the outside of the appliance casing or on the outside of the independent unit or outlet. However, the reset member could be arranged to be operated automatically when the timer resetting operation is performed, for example by the opening of a cover on the timer Storage heaters normally incorporate a variable control thermostat to control the electrical input to the heating elements. The provision of a timer may enable such a variable control thermostat to be dispensed with. CLAIMS

3. An appliance as claimed in claim 1 or claim 2 in which the supply failure detection means and the switch-off means is a latching relay.

4. An appliance as claimed in claim 3 as appended to claim 2 in which the latching relay is arranged to operate the indication means.

5. An appliance as claimed in any of the preceding claims in which the supply failure detection means and the switch-off means are housed within the casing of the appliance.

6. An appliance as claimed in any of claims 1 to 4 in which the supply failure detection means and switch-off means are housed within a casing adapted to be mounted on a surface adjacent to the appliance.

7. An appliance as claimed in claim 5 or claim 6 in which the switch-off means is arranged to be reset by a manually operable reset member which is accessible on the outside of the casing.

8. An appliance as claimed in any of claims 1 to 6 in which the switch-off means is arranged to be reset automatically when the timber resetting operation is performed.

9. A storage heater is accordance with any of the preceding claims which does not incorporate a variable control thermostat to control the electrical input to the heating elements.

10. An electrical appliance intended to be connected to an electrical supply which has predetermined normal and low tariff periods, the appliance being substantially as described herein.