IE880065L

IE880065L - Shower

Info

Publication number: IE880065L
Application number: IE880065A
Authority: IE
Inventors: Nicholas John Beck
Original assignee: Caradon Mira Ltd
Priority date: 1987-01-21
Filing date: 1988-01-11
Publication date: 1988-07-21
Also published as: IE61037B1; GB2200439B; GB2200439A; GB8701278D0

Abstract

The water supplied to an instantaneous electric water heater 7 is preheated by mixing cold water with hot water from a cylinder 1. The pre-heat apparatus 8 comprises a mixing valve 16 having separate inlets connected via respective non-return valves 19,20 to supplies of hot and cold water and an outlet connected via an on/ off solenoid valve 21 to a supply pipe 12 to the electric water heater 7. The pre-heat apparatus 8 further includes a cold water branch pipe 23 by-passing the mixing valve 16 and connected via an on/off solenoid valve 24 to the supply pipe 12. The on/off solenoid valves 21,24 are selectively operable by switching means for controlling flow through either the mixing valve 16 or the branch pipe 23 as required. <IMAGE>

Description

61 037 01 This invention concerns improvements in or relating to showers and in particular to a shower installation having an instantaneous electric water heater for heating a cold water supply to provide a 05 source of hot water.

Such heaters provide a source of hot water on demand by heating cold water flowing continuously through a heat exchanger containing one or more electric heating elements and the final temperature of 10 the hot water is controlled by adjusting the flow rate of the supply for any given power input to the heat ■ exchanger A disadvantage of this type of heater is that using mains cold water the required final temperature 15 of the hot water can often only be obtained at low flow rates even when using the maximum power input and this can lead to sb unsatisfactory spray pattern.

It is an object of this present invention to provide a solution to the above disadvantage. 20 According to the present invention we provide a shower installation comprising an instantaneous electric water heater- for heating a supply of cold water to provide a, source of hot water, means for preheating the cold water supply to the water heater, and 25 valve means for controlling the flow of cold water through either the pre-heat means or & branch pipe bypassing the pre-heat means for supply to the water heater.

By the present invention, pre-heat means for the cold water supply to the water heater enables a higher flow rate to be used for given power input to the water heater to obtain the required final water temperature or the pre-heat means may be by-passed for direct supply of the cold water to the water heater. 01 Any suitable pre-heat means may be used but where there is a source of hot water available, for example in a domestic hot water systeia having a hot water storage cylinder, the pre-heat means conveniently 05 comprises a missing valve for nixing the cold water' with hot. water fro® the storage cylinder.

The mixing valve nay comprise a non-compensating blender unit or a thermostatic control valve and is preferably pre-set to raise the cold water teimserature 10 to a predetermined temperature.

The mixing valve and electric water heater may be combined in a single unit but more preferably they are separate from one another and connected by a single supply pipe* la this way the amount of pipework is 15 reduced and the mixing valve can be located close to the storage cylinder- Is addition, an existing shower using an instantaneous electric water heater can be modified by the addition of pre-heat means according to the invention.

Advantageously, the valve means comprises separate on/off valves for each of the pre-heat m%an.s aad the cold water by-pass. Preferably, the on/off valves are solenoid valves controlled by switch means.

For some applications# for example is as 25 unpres3urised hot water system, a pump may be provided between the pre-heat Means and the water heater to boost the pressure of the water delivered to the water heater.

One embodiment of the invention will now be 30 described in sore detail by way of example only with reference to the accompanying drawing in which the single figure shows the installation of a shower according to the present invention in a vented domestic hot water system.

Referring to the accompanying drawing, a shower according to the present invention is shown installed in. a vented domestic hot water system including a hot water storage cylinder 1 having a thermostatically controlled electric immersion heater (not showaj for heating water in the cylinder 1 to & pre-set temperature, typically B5°C« The cylinder 1 has a:a inlet at the lower end connected by a pipa 2 to a cold water feed tank 3 connected to the mains cold water'supply by a ball float valve 4 for controlling the water level in the feed tank 3* la use,, hot water is dram off fro® the cylinder 1 via a pipe 5 connected to an outlet at the upper end of the cylinder 1 and is replaced by cold water from the feed tank 3- Expansion of water in the cylinder 1 is acconisnodated by a veat pipe 6 extending froa the pipe 5 termin&ting above the feed tank 3- The shower includes an instantaneous electric water heater 7 and apparatus 8 for prfe-heati'mg the cold water supply to the heater 7.

The heater 1 comprises a .casing $ housing a heat exchanger 10 having an' inlet connected through a. flow control valve 11 to a pipe 12 from the pre-heat apparatus 8 end an outlet connected to a shower head 13 by a flexible_plj3eL_i4.

The heat exchanger 10 contains two 4.2 kilowatt electric heating elements Coot shown) for heating water delivered fro® the pre-heat apparatus 8 and the easing 9 mounts respective manually operable control knobs Cnot shown) for selecting a power lapet to the heat exchanger of 0 kilowatts, 4-2 kilowatts or 3.4 kilowatts and for adjusting the flow control \ valve 11 to provide the required flow rate through the heat exchanger 10 to obtain the desired final water temperature for the selected power input.

The pre-heat apparatus 8 comprises a easing IS housing a mixing valve 16 having separate inlets connected to hot and cold water supply pipes 17 and 18 respectively through respective non-return valves 19,20 and an outlet connected to the pips 12 through as, on/off solenoid valve 21 'for controlling • flow of water through the mixing valve 16 and a pump 22 for boosting the pressure of water delivered to the heater 7.

The mixing valve 16 which may be a non-compensating blender unit or a thermostatic control valve is pre-set on installation to mix the hot and cold water in the relative proportions required to heat the cold '^ater to any desired temperature, for example 25°C as compared with a typical mains cold water temperature of 12'^C.

Ib addition, the pre-heat apparatus 8 includes a branch pipe 23 by-passing the mixing valve 16 between the cold water inlet afc one end and the outlet at the other end where the branch pipe 23 is connected between the solenoid valve 21 asfi the pump 22 „ For controlling flow of water through the branch pipe, there is provided an on/off solenoid valve 74 similar., to the valve 21 and both valves are controlled by a switch Cnot shown) mounted on the casing 9 of the electric heater which enables the user to actuate • selectively the valves to direct the flow of cold water through either the mixing valve 16 or the branch pipe 23. in this way# the user can decide whether or not. to use the hot water from the storage cylinder 1 to pre-heat the cold vater supply to the electric heater 7„ ~s~ 02 In operation of the shower above-described, with a typical cold water temperature of 12°e# then using a power input to the heat exchanger of 8-4 kilowatts and no pre-heat of the cold water supply, a final water 05 temperature of 40°C can be obtained with a flow rate of ] 4,4 litres per minute.. However, by pre-heating the cold water supply to 25 C by mixing with hot water from the storage cylinder, the same final ?^ater temperature can be obtained with a flow rate of 8 litres per 2.0 minute.

As will now be appreciated the present invention enables an increase in the flow rate and hence an improved spray pattern to be obtained for a given final water temperature using an instantaneous electric 15 heater without increasing the power input simply by pre~heating the cold water supply.

This is particularly beneficial where a large volume of stored hot water is available at low eost# for example when using Economy 7 electricity to heat 20 the water in the storage cylinder.

Additionally, as the hot water is only used! to pre-heat the cold water supply, the consumption of stored hot water is relatively low. Thus, in the above example, the increased flow rate obtained by pre-25 heating the cold, water supply only consumes hot water at the rate of 2 litres per minute.

Accordingly by providing a large volume storage cylinder and heating by low cost electricity, high flow rate shower® can be obtained using an instaneous 30 electric heater relatively economically.

The invention is not limited to the above embodiment, for example the heat exchanger could have * amy combination of one or more heating .elements to provide any desired heat input.

The pre-heat apparatus may be combined with the electric heater in a single unit but is preferably a ss'oarate unit having the appropriate fittings for connection to the hot and cold water supplies and to the instantaneous electric heater for plumbing in both as original equipment and as an addition to an existing shower.

The shower may be installed in a pressurised hot water system in which case the pump may be omitted and a flow regulator fitted to regulate the flow irrespective of supply pressure changes.

Additionally the hot water system may utilise any suitable means for heating water in the storage cylinder# for example gas, oil or solid fuel boilers.

Finally, although the invention has been particularly described with reference to the use of stored hot water as the means for pre-heating the cold water supply,, it will be appreciated that other preheat means may be used, for example waste or reject heat or low cost recovered heat.

Claims

01 Claims:

1„ A shower installation comprising an instantaneous electric water heater for heating a supply of cold water to provide a source of hot water,, means for pre-05 heating the cold water supply to the water heater., and valve means for controlling the flow of cold water ' • through either the pre-heat means or a branch pipe bypassing the pre-heat xaeans for supply to -the water heater. 10

2. A shower installation according to Claim 1 wherein the pre-heat means coaprises a mixing valve having separate inlets for connection to the cold water supply and to a supply of hot water and a common outlet for connection to the electric water heater. 15

3. A shower installation according to Claim 2 wherein the mixing valve is a non-compensating blender unit,.

4. A shower installation according to Claim 2 wherein the mixing valve is a thermostatic control valve,.,

5. A shower installation according to any one of 20 Claims 2 to 4 wherein the mixing valve is pre~set on installation.

6„ A shower installation according to any one of the preceding Claims wherein the valve means comprises separate on/off valves for each of the pre-heat means 25 and the cold water by-pass-

7. A shower installation according to Claim 6 wherein the on/off valves are solenoid valves controlled by switch means.

8. A shower installation according to any one of the 30 preceding Claims including a pomp positioned between the pre-heat means and the electric water heater.

9. A shower installation according to any one of the preceding Claims wherein the electric water heater includes a heat exchanger having one or more heating -9- 01 elementse a flow control valve for controlling the water flow rate through the heat exchanger and means for selecting the power input to the heat exchanger. (, 10« A shower installation according to any one of the 05 preceding claims substantially as hereinbefore described with reference to the accompanying drawing. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS. \ J