GB2387671A

GB2387671A - A water-heating system controller

Info

Publication number: GB2387671A
Application number: GB0209004A
Authority: GB
Inventors: Derek Cope
Original assignee: GASFORCE Ltd
Current assignee: GASFORCE Ltd
Priority date: 2002-04-19
Filing date: 2002-04-19
Publication date: 2003-10-22
Also published as: GB0209004D0

Abstract

A controller for a water-heating system uses a temperature sensor to heat water when below a predetermined temperature. The controller has a first mode of operation in which the heater is controlled to heat water in the hot water tank to a predetermined temperature, to monitor subsequent activity of the heater operated by the temperature sensor and record said activity in a memory for a predetermined number of days. In a second mode of operation, the heater is controlled to replicate the corresponding activity recorded in the memory. By recording hot water requirements and usage during a predetermined period of time, such as a week or a month, the routine of the household and occupants can be determined and recorded and the water heating system can be subsequently controlled based on these recorded readings.

Description

r 238767 1 A WATER-HEATING SYSTEM CONTROLLER

Background to the Invention

A standard water-heating system is typically controlled by a timer unit. The timer signals to a water heater to operate for pre-programmed periods. During such a period, the operation of the water heater is controlled by a thermostat. The water heater heats up water held in a storage tank. As hot water is used from the tank it is 10 replaced by cold water. The thermostat is set with minimum and maximum settings, for example, 60 C and 70 C respectively such that the water in the storage tank remains within those temperatures.

The ideal settings for the timer vary from person to person and from building to 15 building. For example, a house with a single occupant who works 9am to 5pm Mondays to Fridays is likely to have different hot water requirements to a household having a number of children or to an office or hotel. However, in each case the end objective is the same:- to have hot water available when required whilst keeping the amount of time the water heater is on to a minimum.

In most cases, hot water requirements will be known in advance and the user can program their timer unit accordingly. However, programming of timer units is cumbersome, sometimes complex, and occasionally beyond the abilities of some users. In other cases, hot water requirements cannot be predicted easily. In either 25 case, the timer unit is often not programmed correctly and this results in either hot water not be available when it is required or the hot water heater being on for more than is necessary increasing energy expenditure and bills.

30 Summary of the Invention

According to a first aspect of the present invention, there is provided a controller for a water-heating system comprising a hot water tank, a heater and a temperature sensor, the temperature sensor being arranged to operate the heater if that water 35 output from the water-heating system is below a predetermined temperature, the

t controller having a first mode of operation, each day controlling the heater to heat water in the hot water tank to a predetermined temperature, to monitor subsequent activity of the heater operated by the temperature sensor and record said activity in a memory for a predetermined number of days, the controller then switching to a 5 second mode of operation in which, on each corresponding day, the heater is controlled to replicate the corresponding activity recorded in the memory.

By recording hot water requirements and usage during a predetermined period of time, such as a week or a month, the routine of the household and occupants can be 10 determined and recorded and the water heating system can be subsequently controlled based on these recorded readings.

Brief Description of the Drawings

An example of the present invention will now be described in detail with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a water-heating system incorporating a controller 20 according to the present invention; and, Figure 2 to 5 are graphs illustrating the operation of a water-heating system.

Detailed Description

Figure 1 is a schematic diagram of a water-heating system incorporating a controller according to the present invention. The water-heating system includes a water tank 1 and a primary return pipe 2. A controller 3 includes a clock 4, a switch 5 and a sensor 6. The switch 5 is coupled to a water heater 7 for heating the water in the tank 1.

The controller 3 has two modes of operation. In a first mode, for the period of one week, the controller 3 controls the switch 5 to operate the heater 7 to bring the storage tank up to a predetermined temperature at 5am. During the course of the day,

a reactive heat sensor 10 attached to the primary return pipe 2 monitors the temperature of water output from the tank 1. If the temperature drops below a predetermined level, typically 45 C, the heat sensor 10 controls the heater 7 to bring the temperature of the tank 1 up to the predetermined minimum temperature level.

5 Via the sensor, the controller 3 monitors the operation of the heater 7 and records the time periods of its activity from the clock 4 in a memory 11.

At the end of the first week, the controller 3 switches to its second mode of operation in which it operates the switch 5 from the program in the memory 11 to repeat the 10 heating pattern of the first week. The heat sensor 10 continues to monitor the temperature of water output from the primary return pipe 2 for a drop below the predetermined temperature level and controls the heater 7 to compensate for this.

However, this activity is not recorded by the sensor array 4. An intelligent controller may be provided so as to incorporate this subsequent activity in the recorded 1 5 program.

Figures 2 to 5 show a typical hot water profile for an office block. The Figures are graphs plotting temperature against time. The shaded areas on the graphs indicate operation of the water heater 7. Figure 2 corresponds to operation of the water heater 20 on Monday, Tuesday and Friday of the measured week. It can be seen that the heater 7 is operated at 5am and there is no further demand during the day. Therefore the program in the memory 11 will only record the operation of the heater at the start of the day.

25 Figure 3 corresponds to the operation of the heater 7 on Wednesday and Thursday. It can be seen that in addition to heating the water at the start of the day, due to demand, it is also heated at around 1 Dam and 7pm. The three heating periods would be recorded in the memory 11.

30 Figure 4 corresponds to the operation of the heater 7 on Saturday whilst Figure 5 corresponds to the operation on Sunday. The water is heated once on Saturday and not at all on Sunday.

- - - Whilst the control system has been described as a number of discrete components, it will be appreciated that the units can be combined or divided to suit the particular installation. For example, the sensor 6 and switch 5 may be incorporated into the controller 3. Alternatively, the memory 11 and/or the clock 4 may be separate 5 components to the controller 3. Furthermore, it will be appreciated that the controller of the present invention may be applied to other systems such as central heating systems.

Claims

t Claims:

1. A controller for a water-heating system, the system comprising a hot water tank, a heater and a temperature sensor, the temperature sensor being arranged to 5 operate the heater if that water output from the water-heating system is below a predetermined temperature, the controller having a first mode of operation, in which, at a predetermined time each day for a predetermined number of days, it controls the heater to heat water in the hot water tank to a predetermined temperature, the controller being arranged to then monitor subsequent activity of the heater operated 10 by the temperature sensor and record said activity in a memory, the controller then being arranged to switch to a second mode of operation in which, on each corresponding day, the heater is controlled to replicate the corresponding activity recorded in the memory.

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2. A controller according to claim 1, further comprising sensor means in communication with the controller for monitoring activity of the heater when operated by the temperature sensor.

3. A controller according to claim 1 or 2, further comprising switching means in 20 communication with the controller for controlling the operation of the heater.

4. A controller according to claim 1, 2 or 3, in which the predetermined number of days comprises 7 days.

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5. A method of controlling a water-heating system, the system comprising a hot water tank, a heater and a temperature sensor, the temperature sensor being arranged to operate the heater if that water output from the water-heating system is below a predetermined temperature, the method comprising the steps of: at a predetermined time each day for a predetermined number of days, it controlling 30 the heater to heat water in the hot water tank to a predetermined temperature; monitoring subsequent activity of the heater operated by the temperature sensor and recording said activity;

after said predetermined number of days, controlling the heater in dependence on the recorded activity.

6. A computer program comprising computer code means for performing all the 5 steps of claim 5 when said program is run on a computer.

7. A computer program according to claim 6 embodied on a computer readable rnediim. 10

S. A controller as herein described, with reference to the accompnaying drawings.