GB2153991A

GB2153991A - Central heating system

Info

Publication number: GB2153991A
Application number: GB08502240A
Authority: GB
Inventors: Anthony Felix Colin; Roland Russell
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-02-01
Filing date: 1985-01-29
Publication date: 1985-08-29
Also published as: GB8502240D0; GB2153991B

Abstract

A central heating system includes a main oil, gas or solid fuel fired boiler 10, an auxiliary electrically powered flow boiler 20 and control means 30 for terminating main boiler operation and operating the flow boiler whenever electricity is the more economic fuel, for example during off-peak tariff periods. The boiler 20 may comprise four tubes (40, Figs. 2 and 3) connected in series and containing a respective immersion heater (43). <IMAGE>

Description

SPECIFICATION Central heating system This invention concerns a central heating system of the kind comprising an oil, gas or solid fuel fired boiler adapted to heat water for circulation through a heating circuit to supply heat exchangers such as radiators located at positions remote from the boiler.

The use of oil, gas or even solid fuel fired boilers is popular despite numerous disadvantages including high maintenance costs, provision of storage tanks for oil fired systems, hazard arising from leakage for a gas fired system and the necessary manual fuelling, ash removal and consequent dirt attendant upon a solid fuel system, since the cost per unit of heat is generally somewhat lower than that using electricity.

However, electricity is generally available during "off-peak" periods at reduced prices which compare favourably with the prices of certain other fuels especially oil. Thus various heating systems have evolved using "offpeak" electricity and based on storage of heat during the off-peak periods for dissipation during other periods. Such systems include free standing "night storage heaters", large water reservoirs and various types of underfloor heating. Many such systems, however, are difficult to control and are incapable of providing adequate heat on demand during say a particularly cold spell.

The present invention is based upon the possibility of using electricity as an alternative fuel in a central heating system of the kind referred to whenever its use provides economic advantage.

According to the present invention there is provided a central heating system comprising an oil, gas or solid fuel fired boiler adapted to heat water for circulation through a heating circuit to supply heat exchangers such as radiators located at positions remote from the boiler, characterised by the provision of an electrically powered flow boiler in the heating circuit and control means for automatically disenabling the main boiler and enabling the flow boiler at times when electricity is the more economic fuel.

The invention will be further apparent from the following description, with reference to the figures of the accompanying drawings, which show, by way of example only, one form of central heating system embodying the invention.

Of the drawings: Figure 1 shows a diagrammatic circuit for the central heating system; Figure 2 shows a side view of a preferred form of flow boiler for use in the system of Fig. land Figure 3 shows an end view of the flow boiler seen in the direction of the arrow X on Fig. 2.

Referring firstly to Fig. 1, it will be seen that the central heating system comprises, in known manner, an oil-fired boiler 10 adapted to feed a heat exchange coil 11 within a cylinder 1 2 for domestic hot water under the influence of gravity. The boiler 10 can also feed, through line 13, a plurality of radiators 14, the water then being returned to the boiler 10 through line 1 5. Line 1 5 includes a pump 1 6 adapted to be operated along with the boiler 10 when user settable control means (not shown) usually comprising a timeclock and room thermostat connected in series both call for heat. Separate thermostat (not shown) and valve means 1 8 are provided to control the temperature of the water in the cylinder 1 2.

In accordance with the invention an electrically powered flow boiler 20 is included in line 1 3 to provide an alternative heat source for the system. A motorised 2-way valve 21 is included in line 1 5 to divert water flowing from pump 1 6 through line 22 directly to the boiler 20 when it is operating to avoid wasteful heating of water in the jacket of the boiler 10.

Time-programmed control means 30-preferably provided by an electricity supply authority-act on switch means 31 to cut electrical supply from the boiler 10 thus disenabling it and supply the flow boiler 20 and valve 21 whenever cheap "off-peak" electricity is available.

The flow boiler 20 is also subject to switching with pump 1 6 in response to the user settable time clock and room thermostat.

Presently (January 1984) the cost of 1 KWH of "off-peak" electricity is 1.9p compared with 3.71p for the equivalent heat derived from oil at 23.8p/litre and assuming an oil boiler annual efficiency of 62.5% as suggested by the Chartered Institute of Building Service Engineers, thus illustrating the substantial savings possible for heating during the "off-peak" period-typically from 0030 to 0730 hrs.

Turning now to Figs. 2 and 3, it will be seen that the flow boiler 20 comprises a plurality of tubes 40 extending horizontally and located in spaced relationship above one another in a vertical plane and plumbed in series by interconnecting pipe sections 41.

One end of each tube 40 is closed by a cap 42 whilst the other end terminates in an internally threaded ring which receives a standard electric immersion heater 43 extending longitudinally with the tube and typically of 3 KW. The tubes 40 are carried by support plates 44.

It will be understood that the boiler 20 is of simple and compact construction, the dimensions of the tubes 40 being selected to accommodate whatever standard immersion heater it is desired to use. The boiler may have more or less tubes 40 with associated heaters 43 to provide whatever power is required.

A thermostat (not shown) is provided to sense water temperature in the boiler 20 and to cut supply to the heaters 43 should the sensed temperature exceed a safe operating level of say 82"C.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the scope thereof as defined in the appended claims

Claims

1. A central heating system comprising an oil, gas or solid fuel fired boiler adapted to heat water for circulation through a heating circuit to supply heat exchangers such as radiators located at positions remote from the boiler, characterised by the provision of an electrically powered flow boiler in the heating circuit and control means for automatically disenabling the main boiler and enabling the flow boiler at times when electricity is the more economic fuel.

2. A central heating system according to claim 1 wherein motorised valve means is provided to isolate the main boiler from the heating circuit when the flow boiler is enabled.

3. A central heating system according to either claim 1 or claim 2 wherein both the main boiler and flow boiler are subject to control by user settable time clock and room thermostat means.

4. A central heating system according to any preceding claim wherein said flow boiler comprises a plurality of tubes plumbed in series by interconnecting pipe sections, each said tube being capped at one of its ends and having an internally threaded ring at its other end carrying a standard electric immersion heater extending longitudinally within the tube.

5. A central heating system according to claim 4 wherein said tubes extend horizontally and are located in spaced relationship above one another in a vertical plane.

6. A central heating system according to any preceding claim wherein thermostat means senses water temperature in the flow boiler and cuts supply to the flow boiler if the sensed temperature exceeds a safe operating level.