The present invention relates to heating systems and in particular, but not exclusively, to domestic central heating systems.

Domestic central heating systems typically include a hot water boiler connected by pipe to a series of radiators which radiate heat into the surrounding environment. Each radiator heats a distinct zone and often has a valve to control the rate of heat transfer. Modern central heating systems are usually fitted with highly efficient condensing boilers. These boilers require a temperature drop across the outlet and the return. Present central heating systems are not specifically designed to provide this temperature drop and thus the majority of systems operate at an temperature drop of less than 10%. Condensing boilers are most efficient at a lower outlet temperature (approximately 63 degrees centigrade) than conventional boilers which operate at approximately 84 degrees centigrade. The lower temperatures associated with condensing boilers make it difficult to correctly balance the radiators in the system as most require the full flow rate achievable by the boiler in order to get hot. This compromise usually leads to the raising of the boiler outlet temperature and thus reducing the efficiency of the boiler.

The reason for this increased outlet temperature and thus reduced temperature drop is the difficulty in achieving the required temperature drop across each radiator whilst maintaining the heating effectiveness of the radiator. The rate of heat transfer is exponential with temperature difference, that is to say the temperature of the radiator against ambient room temperature.

If the flow rate through a radiator is too high the radiator temperature will be hot and the temperature drop across the outlet and return of the boiler will be low as the fluid has little time to cool. Although the heat output from each radiator is high, the efficiency of the boiler is low.

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Confimation copy If the flow rate is low, the temperature of the radiator is then low and the heat transfer is also low meaning the room will not heat sufficiently quickly unless the radiator is very large. The heat output from the radiator will be low but the efficiency of the boiler is high. It is an object of the current invention to at least mitigate some of the above problems.

Accordingly, there is provided a method of controlling a central heating system including the steps of:

providing a heating device for generating hot water, a water pump and at least one radiator fluidicly connected to the heating device and pump, each radiator having an inlet valve and an outlet temperature sensor,

the method further including the steps of

operating the pump to pump hot water into the radiator, closing the radiator inlet valve, and opening radiator inlet valve when the outlet temperature sensor drops to a predetermined value.

Advantageously the invention provides the maximum boiler efficiency available through the use of a cooling cycle to allow the radiator temperature to drop to the predetermined temperature. This means that the radiator achieves a high temperature from a high flow rate and then the flow rate stops whilst it cools to the required temperature drop. The radiator is then flushed again and this process repeats in cycles.

Preferably, the system has two or more radiators fluidicly connected in series, each radiator having a bypass flow path wherein the method includes the step of selectively pumping hot water past one or more radiators to a predetermined radiator.

The system has a major advantage over conventional parallel systems in that by delivering series flow of heating fluid it is ensured that the full flow is passed through every radiator regardless of the systems configuration. Radiators therefore require no balancing. Furthermore, there are no detrimental effects associated with valve operation altering the system balance. The system is therefore capable of efficiently outputting increased heat from a radiator than in a current parallel setup. This means that it is possible to reduce the size of the radiator in order to fulfil the rooms heating requirement. This is advantageous both in reducing the cost of the radiators and also in reducing the packaging space required to install the radiators within a room.

Further advantageously, this method transfers less heat overall than a steady state high flow rate system but with far greater boiler efficiency. Furthermore, because no balancing is required the system will have a greater average heat output across the whole system whilst maintaining the efficiency. The method transfers increased heat at a faster rate than a steady state low flow system whilst achieving the same efficiency.

This is achieved by virtue of Newton's Law of cooling which states that the time taken to cool a set temperature varies with temperature differential. By maximising the temperature drop at each radiator, the efficiency of the boiler is increased.

Advantageously, the method allows a high flow rate to be achieved at every radiator. This in turn allows maximum efficiency to be achieved out of the system. The invention will now be described, with reference to the following drawings, in which:

Figure 1 is a schematic view of a system implementing the method according to the present invention; and Figure 2 is a flow diagram setting out the steps of the method of the present invention.

Referring to Figure 1 a plurality of networked radiators 1 are connected in series to a pump 8 and heating device in the form of a condensing boiler 5 by a boiler output line 3 and a boiler return line 4. The boiler return line 4 has a filtration unit 6 for filtering the water. Each radiator 1 has an inlet valve in the form of a network control valve 7. The valves 7, pump 8 and boiler 5 are controlled by the central controller 2. The current method cycles through the radiators 1 to ensure that heating is delivered throughout the whole building. This method can be used to ensure the maximum efficiency available in the complete system and across the boiler. The cycles also enable the central controller 2 to channel the correct amount of flow to each and every radiator regardless of system design. This method is well suited to Pumps 8 with remote variable control flow rates.

Referring to Figure 2, in use the controller 2 operates the following sequence of events. In the sequence below the heat exchange device is assumed to be a radiator but this method is also be applicable to other heat exchange devices.

With all valves 7 closed, controller 2 sends a signal to the valve 7a of a first radiator la to open in order to ensure series circuit flow. The controller 3 then sends a signal to the heating device to heat the heating fluid. The controller 2 sends a signal to the pump 8 to begin circulating the heating fluid.

The controller 2 processes input data from the radiator control valves 7 concerning the individual ambient room temperatures. The radiator control valve 7 also exports data to the controller 2 concerning the radiator fluid outlet temperature. The controller 2 processes the data and calculates the required radiator valve 7 opening sequence based upon the user inputs of timings, radiator priority and required temperature. The controller then calculates the temperature drop for each radiator 1 in order to maximise the heating device's efficiency and the operator's requirements. The controller 2 controls the radiator control valves 7 to open each valve in a predetermined series. Each valve 7 remains open until a relatively steady temperature is recorded at the outlet of the radiator, at which point the valve 7 is closed. The radiator then begins to cool. This outlet temperature may also be determined to be within a percentage of the input temperature if it proves more efficient. A signal is then returned to the controller signifying the completion of the pulse of that particular radiator. The controller 2 then signals the next radiator in the sequence to open the control valve 7. The next sequenced radiator then begins its heating cycle. This is repeated throughout the complete predetermined sequence of heat exchange devices. At the end of the cooling cycle each radiator control valve 7 signals the controller identifying a successful cooling cycle and a readiness to receive the next pulse. The controller calculates data received from the radiator control valves 7 to optimise the timing cycle of the system. The radiator cooling times are variable and the unit controller calculates the new sequences as the cooling periods increase. The cooling periods increase due to the decreased temperature gradient as the room heats up. The controller also receives data concerning the heating device's optimised efficient operation settings. The controller continually calculates cooling times and temperatures across the system in order to achieve the optimum system requirements. If required it may also vary fluid flow through a variable pump. A resistive filtration unit 6 is implemented intermittently by the controller by diverting the flow through the filter. This system allows complete control over a building's heating requirements for both zone control and temperature requirements. The method of the present invention overcomes a major disadvantage of zone control and that is through the variation of zone fluid flow against the requirements of balancing for the complete system. The method of the present invention requires no balancing and thus has no disadvantages when using zone control heating methods. The heating requirements are continually recalculated so any number of zone heating variations will not affect the efficiency. This coupled with an estimated efficiency increase of up to 10% from a condensing boiler operating under optimised conditions provides a substantial advantage.