The present invention relates to devices for controlling heating or air conditioning systems (hereinafter the term "heating system" will be used). In particular, but not exclusively, the invention relates to a timer control which provides simplified control of a heating system and simplified display of the current setting.

It is known to provide heating controls that automatically control a heating system according to settings specified by a user. In addition to thermostatic control, the heating control may also control the system such that it only operates at times pre-set by the user.

For some time, the trend has been for heating controls to become more complex to provide increased functionality. However, this has led to the heating controls becoming less intuitive to use. The input controls can be in various forms, such as switches, tappets, push buttons, sliders, dials, touch sensitive buttons and/or pointers. Setting a programme may call for a multiplicity of user actions, often involving multiple input controls, and/or require the user to go through complex sequences. Also, the programmes set may not be displayed in an easily comprehensible and readily accessible way. The physical display of heating controls is typically relatively small and the graphic display is limited. In particular, it can be difficult to identify which parameter is being displayed.

As a result of this, many people only use a few of the available functions or do not use them at all. The elderly or people with disabilities (such as learning difficulties or impairment of sight) may in particular find existing heating controls to be difficult to operate. Apart from the inconvenience and increased energy cost to the user, there is likely to be an environmental cost, since buildings are being heated at times when this is not required. It is desirable to provide a heating control which allows simple, intuitive operation. This may involve one or more of fewer input controls or fewer user actions required or fewer/simpler programming sequences or simpler display. It is desirable to provide a heating control which is easier to operate by people with disabilities or impairments.

In particular, the complexity of heating controls can be a disincentive to users wishing to make short term 'one-off or occasional variations in the set programme, especially when the user has later to remember to reset the controls to the original programme. An instance of such a short term need would be when the building is not occupied for a period during the day when the premises would normally be occupied and so are programmed to be heated. In these circumstances simply turning the heating off or reducing the temperature setting of a thermostat would result in the premises being cold on return. A converse example would be when heating is required at a time when it is not normally programmed to be on (such as for a morning start at an unusually early time).

It is desirable to provide a heating control which allows a short term interruption to the current setting. It is desirable to provide a heating control which does not require further adjustment by the user following the short term interruption to the current setting.

According to the present invention there is provided a heating control device for controlling the operation of a heating system, the device comprising: a countdown timer member which is operable to switch the heating system from a first operating state to a second operating state for a time duration selected by a user, wherein the countdown timer member is operable using an input control which is movable by a single action of the user from a first starting position to a second position in which the input control specifies and displays the time duration selected by the user. The heating control device may include time duration indications provided adjacent to the movable input control. The input control may include a pointer and moving the input control such that the pointer points to a particular time duration indication may both specify and display the time duration.

The countdown timer member may include biasing means for progressively returning the movable input control to the first starting position during the selected time duration, thus continuously displaying the time period remaining before the heating system switches back to the first operating state.

The movable input control may comprise a rotary dial. Alternatively, the movable input control may comprise a slider or the like.

The biasing means may comprise a spring for progressively returning the movable input control to the first starting position. The countdown timer member may therefore be clockwork and independent of any other power source.

The countdown timer member may be independent of the current time.

The movable input control may include electrical contacts in electrical connection with an electrical circuit of the heating control device when the input control is at the first starting position. The countdown timer member may be adapted such that moving the movable input control causes separation of the electrical contacts with the electrical circuit for the time duration selected by the user. Alternatively, the countdown timer member may be adapted such that moving the movable input control causes the electrical contacts to break with a first portion of the electrical circuit and to make with a second portion of the electrical circuit for the time duration selected by the user. The countdown timer member may be operable to switch the heating system from an off operating state to an on operating state for the time duration selected by the user. Alternatively or in addition, the countdown timer member may be operable to switch the heating system from an on operating state to an off operating state for the time duration selected by the user.

The heating control device may comprise a programmer, timer or thermostat. Alternatively, the heating control device may be a separate device which is connectable to other heating control devices.

The countdown timer member may be connectable such that one or more predetermined heating system controls still have precedence for controlling the heating system when the movable input control is operated. The predetermined heating system control may comprise thermostatic control such as frost thermostatic control.

The heating control device may be adapted such that, following selection of the time duration by the user, the time duration can be altered or cancelled by the user before the expiry of the selected time duration. The time duration may be altered or cancelled by moving the movable input control by a single action of the user.

The heating control device may include status indication means. The status indication means may be adapted to indicate that the heating system is in the second operating state for the time duration selected by the user. The status indication means may be adapted to indicate that the heating system is in the first operating state and/or that the time duration selected by the user has expired.

The heating control may be adapted to be easier to use by users with disabilities. The input control may be a rotary dial having a diameter greater than three centimetres, preferably greater than five centimetres. The rotary dial may have a gripping member provided around its circumference.

The heating control may include audible indications for movement of the input control. The audible indications may comprise a click or the like for a degree of movement of the input control such as for each hour of time duration selected. Alternatively or in addition, the audible indications may comprise voice indications of the time duration selected.

The time duration indications may be provided in a large format. Alternatively or in addition, the time duration indications may be provided in Braille.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a front view of a heating control device;

Figure 2 is a schematic diagram indicating the circuitry of the heating control device of Figure 1 ;

Figure 3 is an alternative schematic diagram of the circuitry of the heating control device of Figure 1 ;

Figure 4 shows an alternative embodiment of a heating control device; and

Figure 5 is a schematic diagram indicating the circuitry of the heating control device of Figure 4.

Figure 1 shows a heating control device 10 for controlling the operation of a heating system (not shown). The device 10 comprises a mountable housing 12. To provide thermostatic control, an input control in the form of a rotary dial 100 to allow a user to select the desired temperature. The device also includes a countdown timer which is operable to switch the heating system from a first operating state to a second operating state for a time duration selected by the user. The first operating state can be an off operating state and the heating system is switched to an on operating state, or the first operating state can be an on operating state and the heating system is switched to an off operating state.

This is achieved using an input control, also in the form of a rotary dial 20. The rotary dial 20 includes a pointer 24 and time duration indications 22 are provided around the dial 20. Using a single action, the user can rotate the dial 20 clockwise from the starting position shown in Figure 1 to a second position in which the pointer points to the desired time duration. When this is done, the heating control device 10 switches the heating system from the first to the second operating state for the selected time duration. The rotary dial 20 therefore specifies and displays the selected time duration.

After expiry of the selected time duration, the heating control device 10 switches the heating system back to the first operating state without any interventions or actions required by the user. However, it is possible for the user to alter or cancel the current time duration before expiry simply by rotating the rotary dial 20 clockwise to increase the time duration, anticlockwise to decrease the time duration or anticlockwise to the starting position to cancel the time duration.

The countdown timer includes biasing means in the form of a spring for progressively (linearly) returning the rotary dial 20 to the starting position during the selected time duration. Therefore, the rotary dial 20 continuously displays the time period remaining before the heating system switches back to the first operating state. Since the rotary dial 20 is spring driven, the countdown timer is clockwork and independent of any other power source. Rotating the dial 20 from the start position winds the spring which provides the force required to return the rotary dial 20 to the start position. The countdown timer is also independent of the current time and the user does not need to consider any time of day settings when operating the countdown timer.

At the starting position, electrical contacts 30 of the rotary dial 20 are in connection with an electrical circuit of the heating control device 10. Rotating the rotary dial 20 causes separation of the electrical contacts with the electrical circuit for the selected time duration, after which the contacts again connect with the electrical circuit. The open contacts are shown in Figure 2. The thermostatic control also has its own contacts 102 which are in series with the timer contacts 30.

Figure 2 relates to an arrangement in which the heating system is switched to an off state when the dial 20 is rotated. When the dial 20 is at the start position, the contacts 30 of the countdown timer are closed. Thus the thermostat will function in the normal way to maintain the temperature level set on the thermostat. When the user rotates the dial 20 to select a time duration during which the heating is to be off, the contacts 7 open, the circuit is broken and the heating is stopped for the selected time duration. The thermostat will not now have control of the heating system.

This is a very simple and easy to manufacture arrangement. However, arranging the circuit so that the heating system is switched to an on state when the dial 20 is rotated, or can do both, is only a slightly more complex circuit as the skilled person will appreciate.

Many modern thermostats operate using a changeover relay that switches the 'live in' from the 'demand' terminal to a 'satisfied' terminal. For instance, this arrangement can be used where the heating system requires the operation of a valve to turn the heating off. Such thermostats typically provide for four terminals: Common ( ¹ C), Demand ( ¹ D'), Satisfied ('S')and Neutral ( ¹ N'), plus an earth connection. Figure 3 shows an alternative wiring arrangement for this type of thermostat.

The countdown timer can also be connected such that a predetermined heating system control, such as frost thermostatic control, maintains precedence for controlling the heating system even if the rotary dial 20 is operated. Again, this arrangement is only slightly more complex.

The heating control device 10 can include status indication means to indicate that the heating system is in the second operating state for the time duration selected by the user, or to indicate that the heating system is in the first operating state and/or that the time duration selected by the user has expired.

In particular, the heating control device 10 is adapted to be easier to use for users with disabilities or impairments. The rotary dial 20 has a large diameter of six centimetres and includes a grip (not shown) around its circumference. Audible indications are provided for movement of the rotary dial 20. These comprise a click for each hour of time duration selected. The time duration indications are provided in large font and could also be provided in Braille.

An alternative embodiment of the present invention is shown in Figures 4 and 5. Like features are given like reference numerals. As before, the device includes a countdown timer which is operable using a rotary dial 20 to switch the heating system from a first operating state to a second operating state for a time duration selected by the user. However, in this embodiment, the first operating state relates to a first temperature and the second operating state relates to a second temperature.

A primary thermostat is set using a second rotary dial 100, and a secondary thermostat is set using a third rotary dial 110. Figure 5 shows that the countdown timer controls a switch 40 which is arranged to select one of the two separate thermostats via contacts 102 and 110. When the rotary dial 20 controlling the switch 14 is at the start position, the switch closes the circuit to the primary thermostat via contact 102. Thus the main thermostat will determine the temperature to be maintained. When the user rotates the rotary dial 20, the switch 40 disconnects from the circuit to the primary thermostat and makes contact with the circuit to the secondary thermostat for the selected duration. Hence the temperature set on this secondary thermostat will determine the temperature level to be maintained during the selected time duration. When the rotary dial 20 reaches the start position at expiry of the selected time duration, the switch 14 reverts to contact 102 so that control is restored to the primary thermostat.

Both of the above embodiments relate to the combination of the countdown timer with a thermostat. While this is only one of the options for incorporating the countdown timer with heating controls, it does offer particular advantages. A room thermostat is typically conveniently located and it is a common and simple control familiar to most users. Therefore, even an impaired user will be able to ultilise their knowledge of room thermostats to understand an only slightly more complex control which includes the countdown timer.

The present invention provides a heating control which allows simple, intuitive operation. A single input control and a single user action is all that is required to achieve the desired result of altering the existing heating setting for a period of time. No further adjustment is required by the user to return the control to the original settings. The selected time duration is displayed by the input control which avoids confusion.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.