IE86968B1

IE86968B1 - Improvements to boilers

Info

Publication number: IE86968B1
Application number: IE20170155A
Authority: IE
Inventors: Mackle Gerard; Dolan Niall
Original assignee: Warmflow Engineering Company Ltd
Priority date: 2016-08-04
Filing date: 2017-07-28
Publication date: 2019-04-03
Also published as: GB2552701B; GB2552701A; IE20170155A1

Abstract

A combination boiler comprises a water storage tank, a heat exchanger, a burner for heating water in the storage tank, a flow detection device for detecting flow of inlet water to the heat exchanger, a pump for pumping water from the water storage tank to the heat exchanger, and a controller. The controller is in communication with the flow detection device, the burner, the pump and a temperature sensing means associated with the water storage tank, and comprises a delaying means adapted to delay or prevent the burner from igniting for a predetermined time period after activation of the flow detection device or until the water in the storage tank falls to or below a threshold temperature. <Figure 4>

Description

COMBINATION BOILER WITH FIRING DELAYING MEANS The present application relates to an improved combination boiler.

Background to the invention Combination or "combi" boilers are a well known means of heating water for sanitary use and continue to have a significant share of the boiler market place.

Storage combination boilers utilise a storage tank and heat exchanger coupled to a boiler shell with a burner to provide both domestic hot water (DHW) and space heating. A call for DHW is detected by a flow detection device which activates the burner and a pump. Inlet water passes through a heat exchanger and is heated by the water pumped from the storage tank. This standard mode of operation has inherent inefficiencies especially with small demands such as a short draw off of water for hand washing.

Summary of the Invention In one aspect of the present invention there is provided a combination boiler comprising a water storage tank, a heat exchanger, a burner for heating water in the storage tank, a flow detection device for detecting flow of inlet water to the heat exchanger, a pump for pumping water from the water storage tank to the heat exchanger, and a controller, wherein controller is in communication with the flow detection device, the burner, the pump and a temperature sensing means associated with the water storage tank; and wherein the controller comprises a delaying means and is adapted to delay or prevent the burner from igniting for a predetermined time period after activation of the flow detection device or until the water in the storage tank falls to or below a threshold temperature.

P179699. IE.02 Conveniently, the temperature sensing means associated with the water storage tank may comprise any suitable device such as, but not limited to, one or more thermostats, thermistors, or thermocouples or combinations therefor.

Optionally, the burner is coupled to a boiler shell.

Conveniently, the delaying means comprises a timer that is adapted to measure the length of time of activation of the flow detection device.

Advantageously, the timer may comprise any suitable timer, for example but not limited to, a chip or integrated circuit.

Optionally, in embodiments the predetermined time period is in the range of two to three minutes. Such a period of two to three minutes has been found to be appropriate for boilers having a rating of up to 40kW.

Optionally, in embodiments, the predetermined time period is approximately two minutes and thirty seconds.

Optionally, the flow detection device comprises a flow switch, a flow sensor or a temperature change monitor.

Optionally, the threshold temperature is approximately 50°C.

Optionally, the threshold temperature is a selected pre-set input to controller.

Alternatively, the threshold temperature is variable and determined by the controller, optionally further in real time.

It will be understood that the threshold temperature is a lower temperature than a predetermined reference temperature; the reference temperature being a desired upper temperature of the water in the water storage tank which when reached, the burner is switched off.

Pt79699.IE.02 In accordance with a further aspect of the invention there is provided a method of controlling the operation of a combination boiler having a water storage tank, a heat exchanger, a burner for heating water in the storage tank, a pump for pumping water from the water storage tank to the heat exchanger, a flow detection device for detecting flow of inlet water to the heat exchanger, a temperature sensing means associated with the water storage tank, and a controller comprising a delaying means to delay or prevent the burner from igniting, the method comprising the steps of: (a) detecting the flow of input water to the heat exchanger by detecting the triggering of the flow detection device; (b) activating the pump to pump stored warm water from the water storage tank to the heat exchanger; and (c) delaying the ignition of the burner for a predetermined time period after the activation of the flow detection device or until the water in the storage tank falls to or below a threshold temperature.

Various examples and aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrate a number of exemplary aspects and implementations. The invention is also capable of other and different aspects and implementations, and its several details can be modified in various respects, all without departing from the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as including, comprising, having, containing, or involving, and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term comprising is considered synonymous with the terms including or containing for applicable legal purposes.

P179699.IE.02 Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

All singular forms of members, or any other components described herein are understood to include plural forms thereof and vice versa.

Brief description of the drawings Embodiments of the present invention will now be described by way of example only, and with reference to the accompanying figures in which: Figure 1 is a perspective view of an exemplary combination boiler in accordance with invention; Figure 2 is a chart showing burner firings for a conventional combination boiler over a typical 24 hour period; Figure 3 is a chart showing burner firings for a combination boiler in accordance with the present invention over a typical 24 hour period; and Figure 4 is a flow chart showing the steps of operation of a controller of a combination boiler in accordance with the present invention.

Description of the Preferred Embodiments With reference to Figure 1 there is shown an exemplary combination boiler 1 for providing both DHW and space heating comprising a water storage tank 2, a heat exchanger 3 coupled to a boiler shell 4 with a burner 5. In known combination boilers, a call for DHW is detected by a flow detection device 6 which activates the P179699.IE.02 burner 5 and a pump 7. Inlet water passes through the heat exchanger 3 and is heated by the water pumped from the storage tank 2.

In a conventional combination boiler, water in the storage tank is stored at a first temperature, e.g. 60°C. Once the temperature drops to a second temperature, e.g. 45°C, as measured by a temperature sensing means such as a thermostat (not shown) which communicates with the burner, the burner ignites and fires until the water is raised once again to the first temperature. Such a temperature decrease is an inevitable function of stored water being drawn off to heat inlet water at the heat exchanger and through natural heat loss to the surroundings. Thus the water in the storage tank is heated when the flow detection device 6 detects a call for DHW, and also when the temperature of the stored water reaches a predetermined second temperature.

It has been noted that this conventional control strategy can lead to the burner firing when there is already enough stored energy in the storage tank to meet a demand for DHW, in particular where there are small demands such as a short draw off of water for hand washing.

In accordance with the present invention, the combination boiler is further provided with a controller 8 which delays or prevents the burner igniting when there is sufficient stored energy in the storage tank 2 to meet the demand for inlet water heating at the heat exchanger 3.

In this way, the burner is not automatically activated upon each demand for DHW, but rather is delayed from igniting for a predetermined time period after activation of the flow detection device. If during the delay, or after the delay, the temperature of the water in the water storage tank remains above a threshold temperature, the burner is not ignited. However, if during the delay, or after the delay, the water in the water storage tank lowers to the threshold temperature, the burner is ignited.

The delaying means of the controller 8 comprises a timer. The timer of controller 8 may comprise any suitable timer, for example but not limited to, a chip or integrated circuit.

P179699.IE.02 Controller 8 is in communication with the flow detection device 6, the burner 5 (either directly or indirectly) and the pump 7. In an alternative embodiment, the controller is in communication with a temperature sensing means, such as a thermostat, associated with the water storage tank 2 which measures the temperature of the water in said storage tank.

Activation of the flow detection device 6 sends an input to the controller 8 which is operable to set a predetermined delay on the activation of the burner 5, either directly with the burner, or in an alternative embodiment, via the temperature sensing means. A delay in the range of 2 to 3 minutes has been found to be particularly suitable for example with boilers rated at up to 40kW, however other delay durations may be employed. In this way, thus the burner 5 only activates once the water temperature in the storage tank drops to or below the threshold temperature, or the draw off lasts longer than the pre-determined timed delay, rather than each time stored water is pumped to the heat exchanger.

The threshold temperature may either be a pre-selected temperature value inputted to the controller, or may alternatively be a variable temperature value determined by the controller, optionally in real time.

For example, the threshold temperature may be determined by the controller based upon a calculation of the amount of energy still available in the storage tank. Such a calculation could be performed by the controller taking outputs from sensing devices (e.g. temperature sensors) associated with the water storage, tank together with information on the tank’s storage volume. A comparison with the temperature and flow rate of the water being drawn off would enable a real time determination if there was enough energy available in the storage tank, with the threshold temperature adjusted by the controller accordingly.

Measurement of the duration of the draw off is made by determining the length of time the flow detection device is activated.

Measurement of the temperature of the water at the storage tank is determined by the temperature sensing means. In this way, the controller 8 takes an output from the P179699. IE.02 temperature sensing means and determines if there is sufficient stored energy in the storage tank 2 to meet the demand for inlet water heating at the heat exchanger 3.

During the time delay, the burner 5 does not ignite and so the overall number of burner ignitions over a typical 24 hour period is reduced when compared to a conventional combination boiler. This is shown schematically in Figures 2 and 3 where each vertical line indicates a burner ignition.

Figure 2 shows burner firings for a conventional combination boiler over a typical 24 hour period, the typical period being taken as the XL tapping pattern profile defined by the Official Journal of the European Union (EU) No 814/2013. Figure 3 shows the same data for a combination boiler in accordance with the present invention.

An outline of the steps of the operating sequence of a combination boiler in accordance with the invention shown in Figure 4.

In this way, the present invention manages the firing of the burner when a DHW call is detected in order to prevent the burner firing if not required. Thus the invention prevents burner firing on short demands whilst ensuring enough energy is available for large demands. This reduces the amount of fuel consumed and produces a more efficient and cost effective combination boiler as a smaller storage tank and less insulation can be utilised to achieve the same level of efficiency of a conventional combination boiler.

Claims

1. A combination boiler comprising a water storage tank, a heat exchanger, a burner for heating water in the storage tank, a flow detection device for detecting flow of inlet water to the heat exchanger, a pump for pumping water from the water storage tank to the heat exchanger, and a controller, wherein the controller is in communication with the flow detection device, the burner, the pump and a temperature sensing means associated with the water storage tank, and wherein the controller comprises a delaying means and is adapted to delay or prevent the burner from igniting for a predetermined time period after activation of the flow detection device or until the water in the storage tank falls to or below a threshold temperature.

2. A combination boiler as claimed in claim 1, wherein the delaying means comprises a timer that is adapted to measure the length of time of activation of the flow detection device.

3. A combination boiler as claimed in claim 1 or claim 2, wherein the flow detection device is a flow switch.

4. A combination boiler as claimed in claim 2, wherein the timer comprises one or more of a chip or integrated circuit.

5. A combination boiler as claimed in any preceding claim, wherein the predetermined time period is between 2 and 3 minutes.

6. A combination boiler as claimed in any preceding claim, wherein the predetermined time period is approximately two minutes and thirty seconds. P179699.IE.02

7. A combination boiler as claimed in any preceding claim, wherein the controller communicates with the burner via the temperature sensing means associated with the water storage tank.

8. A combination boiler as claimed in any preceding claim, wherein the temperature sensing means comprises one or more thermostats, thermocouples, thermistors or a combination thereof.

9. A method of controlling the operation of a combination boiler having a water storage tank, a heat exchanger, a burner for heating water in the storage tank, a pump for pumping water from water storage tank to the heat exchanger, a flow detection device for detecting flow of inlet water to the heat exchanger, a temperature sensing means associated with the water storage tank, and a controller comprising a delaying means to delay or prevent the burner from igniting, the method comprising the steps of: (a) detecting the flow of input water to the heat exchanger by detecting the triggering of the flow detection device; (b) activating the pump to pump stored warm water from the water storage tank to the heat exchanger; and (c) delaying the ignition of the burner for a predetermined time period after the activation of the flow detection device or until the water in the storage tank falls to or below a threshold temperature.

10. A method of controlling the operation of combination boiler as claimed in claim 9, wherein the predetermined time period is in the range of 2 to 3 minutes.

11. A method of controlling the operation of combination boiler as claimed in claim 9 or claim 10, wherein the threshold temperature is approximately 50°C.