GB2230329A

GB2230329A - Water heating installations

Info

Publication number: GB2230329A
Application number: GB9008066A
Authority: GB
Inventors: George Hanson-Graville
Original assignee: HYDRO SPARTAN Ltd
Current assignee: HYDRO SPARTAN Ltd
Priority date: 1989-04-11
Filing date: 1990-04-10
Publication date: 1990-10-17
Also published as: GB8908136D0; GB9008066D0

Abstract

A water heating installation comprises a water heating cylinder having a main volume B therein, and a separate upper primary heating space A above the main volume. An outlet from space A passes water through a coil 2 in volume B to an external heating circuit including a circulating pump 17, a boiler, and a control valve 16. The space A has an inlet from valve 16, a heat sensor 15 in the inlet 7 controlling the valve 16 to either circulate the hot water from the coil 2 back to space A, or through the external circuit. The volume B has a cold water inlet 4 and a heated water outlet 5. The space A has a heat exchange coil 8 in it with an inlet 7 connected to mains pressure water and an outlet 6 for hot water, and heating of water in the coil 8 is largely unaffected by withdrawal of water from the main volume outlet 5. <IMAGE>

Description

Improvements in Water Heating Installations This invention relates to improvements in water heating installations, particularly for the supply of hot water for domestic purposes.

At present, it is customary practice to provide hot water either by a primary heating coil, which heats the main body of water by heat transfer from preheated water circulated through the coil from a primary heater such as a back boiler in a fire place for example, or by an electrical immersion heater. The water pressure in the cylinder in a vented system is governed by the static head of the cold water feed above the cylinder. This can result in poor flow to baths basins and showers where the cold storage tank is situated at low level, as in flats for example.

To overcome this, unvented pressurised cylinders are now used which are very expensive and require safety valves regulators, expansion vessels and other equipment with which to regulate the pressure to the cylinder and also to accomodate the thermal expansion of the heated water. To try to keep down running costs, sometimes a heating coil is fitted into the top of the cylinder, and fed from the mains direct to taps and showers.

To enable these to operate succesfully, the main body of water must be preheated by either a primary coil from a boiler, or by an electrical immersion heater. This main body serves as a heat bank from which the mains fed coil extracts heat during the passage of cold water from the mains through the coil. Heat extraction is slow and requires that the water is heated quickly by the coil and kept hot.

A major disadvantage is that if water from the main volume of the cylinder should be drawn off, by using taps in the appropriate circuit, heat is lost from the main volume of water as the hot water is replaced by unheated water and heat transfer to the mains fed coil is reduced.

An object of the invention is to provide an improved water heating installation which can overcome some of these disadvantages while retaining simplicity and economy of construction and operation.

The invention provides an improved water heating installation comprising a water heating cylinder, having a main volume therein, through which a primary heating coil passes, said coil communicating with a primary heating space in said cylinder which is separated from said main volume, and a further heat transfer coil for circulating a yet further supply of water through said primary heating space.

The primary heating coil may form a closed circuit, via an external connection from the primary heating space, which includes a circulating pump.

A preferred embodiment of water heating installation according to the invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 is a vertical cross-sectional view of a water heating installation according to the invention; Fig. 2 is a partial external view from the right in Fig. 1 of the upper part of the installation; and Fig. 3 is a view from above of the interior of the upper part of the installation, as seen with the top wall removed.

Referring to the drawings, in Fig. 1, a water heating installation according to the invention comprises a water heating cylinder 1, divided into a main portion B containing a body of secondary hot water, and an upper compartment A, separated from the main portion B by an inverted domed wall.

The upper compartment constitutes a primary heat bank. The main portion has a cold water inlet 4 at the bottom and a hot water draw-off connection 5 near the top. A primary coil 2, communicating with the upper compartment A is located in the main portion, and is connected via an

islet 12, through a circulating pump 17 to an

outlet 11 from the upper compartment A. Upper compartment A also has a heating coil 8 therein which is in the form of a conical spiral, and has a cold water inlet 7 and hot water outlet 6.

The main part B is provided with a drain plug 13, and a vent pipe 9, whilst the upper compartment A has an automatic air vent 10. A thermostat 15 in the cold water inlet pipe 7 is connected to a valve 16 controlling the circulation of water from compartment A through the main part B, to coordinate this circulation with the water in the circuit of coil 8.

If the latter is hot enough, the water from compartment A is diverted via a pipe 18 to a respective heating circuit.

In use, during the initial heating of the main body of water in the lower part B. hot water first passes into the heat bank formed by compartment A' having perhaps been pre heated by an immersion heater or back boiler; this rapidly heats the water in space A, thereby heating the water in coil 8, supplied from the mains. Heat is also passed through the wall dividing the parts A and B, heating the upper part of the main body of water. The heated water from compartment A then flows through the secondary coil 2, returnimg to the compartment A in a closed circuit. The main body of water is thus heated, and this provides a secondary heat bank, with a large thermal inertia becAuse of its large volume.

As water is drawn from the top coil 8, via pipe 6, fresh mains water enters via pipe 7. This water passes through a series of loops, contained in compartment A, extracing heat from the water therein. A thermostat 15 senses the change in the water temparature entering the coil, and controls a valve 16 to divert the full output from the main part B to the

compartment A, instead of circulating it in 9 host water circuitL keeping the water in compartment A hot to enable the maximum heat exchange between the coil 8 and the water in compartment A.

The water cooled by this heat exchange will pass through the coil 2 in turn extracting heat from the main body of water prior to returning to the boiler to be super heated and returned to compartment A. At the same time any residual heat in the main body of water will be conducted through the wall separating the parts, This method of heating a larger volume of water maintains a heat bank capable of heating a mains circuit.

Claims

1. A water heating installation, comprising a water heating cylinder having a main volume therein, through which a primary heating coil passes, said coil communicating with a smaller primary heating space in said cylinder which is separated from said main volume, and a further heat transfer coil for circulating a yet further supply of water through said primary heating space.

2. An installation according to Claim 1, wherein the primary heating space and the primary heating coil are connected in a closed circuit which passes outside the cylinder, and includes a circulating pump.

3. An installation according to Claim 2, wherein the closed circuit has a connection via a control valve to heat utilising devices.

4. An installation according to Claim 3 wherein the control valve is operated by means responsive to a temparature sensor in the inlet connection of the further heat transfer coil.

5. An installation according to any preceding Claim, wherein the main volume has a cold water inlet near the base thereof and a heated water outlet near its top, the primary heating space has an inlet from a closed circuit, and an outlet via the primary heating coil into the circuit, and the further heat transfer coil has a cold water inlet and an outlet for heated water.

6. An installation accorcing to any preceding Claim, wherein the main volume and the primary heating space are separated by an inverted domed wall, the primary heating space being of eliptical vertical cross-section.

7. An installation according to Claim 6 wherein the further heat transfer coil is a conical spiral.

8. An installation according to Claim 7 wherein the primary heating space has an automatic air vent.

9. An installation according to Claim 1, comprising a water heating cylinder having a main volume and a separate upper primary heating space above the main volume, an outlet from the upper space passing through a coil in the main volume to an external circuit including a circulating pump and a control valve, the upper space having an inlet from the control valve, and containing a heat exhange coil with an inlet for unheated water and an outlet for heated water, a heat sensor in the inlet controling the control valve to either circulate water from the coil in the main volume to the upper space, or through the external circuit.

10. A water heating installation, substantially as herein before described with reference to and as illustrated in the accompanying drawings.