GB2375594A

GB2375594A - Water heater pipe insulation

Info

Publication number: GB2375594A
Application number: GB0217719A
Authority: GB
Inventors: John Edward Vallis
Original assignee: ZIP HEATERS
Current assignee: ZIP HEATERS
Priority date: 2000-07-18
Filing date: 2001-07-11
Publication date: 2002-11-20
Anticipated expiration: 2021-07-11
Also published as: GB0217719D0; GB2375595B; GB0217720D0; GB2375594B; GB2375595A

Abstract

A sleeve 18 of thermally-insulating material is in contact with an expansion pipe 16 that connects a hot water reservoir 10 with a cold water reservoir 12. The sleeve extends to at least the depth of water in the cold water reservoir and thermally separates the water from the expansion pipe. A feed pipe 14 supplies cold water to the lower reservoir 10 which contains a water heating means. The pipes may be surrounded by collars 26 and 28 of low thermal conductivity plastics at the point of entry into the cold water reservoir to further impede heat transfer. The expansion pipe permits heated water forced out of the hot water reservoir by expansion to return to the cold water reservoir.

Description

Improvements relating to water heaters Field of invention This invention concerns water heaters of the type in which cold water is stored in a reservoir above a second lower reservoir of heated water, for maintaining the level in the second reservoir.

Background to the invention In water heaters of this type the heat from the lower reservoir has been found to raise the temperature of the volume of cold water to unacceptable levels and it is an object of the present invention to overcome this problem.

Summary of the invention According to one aspect of the present invention there is provided a water heater comprising upper and lower reservoirs in which cold water is stored in the upper reservoir for feeding the lower reservoir which contains water heating means, with an interconnecting passage for transferring cold water from the upper reservoir to the lower to maintain the level therein and an expansion pipe to permit heated water forced out of the lower reservoir by expansion to return to the upper reservoir, wherein the expansion pipe extends into and upwardly through the upper reservoir and means is provided to thermally separate the body of water in the upper reservoir from the expansion pipe extending upwardly through the upper reservoir, thereby to reduce the transfer of heat from the expansion pipe to the water in the upper reservoir, said means comprising a sleeve which surrounds the expansion pipe to at least the depth of the water in the upper reservoir and wherein the sleeve is formed from thermally insulating materialand is in contact with the expansion pipe.

Preferably a collar of material having low thermal conductivity relative to copper (such as a suitable plastics material) surrounds the expansion pipe where it passes through a wall of the upper reservoir so as to reduce the conduction of heat from the pipe to the upper reservoir.

Preferably a similar collar of low thermal conductivity material surrounds the feed pipe (from the upper reservoir to the lower) where it passes through a wall of the upper reservoir to inhibit the transfer of heat from the feed pipe to the upper reservoir.

By wall is meant any wall of the reservoir including the base thereof.

Typically the upper end of the expansion pipe is bent to form an inverted U-bend so if that water is forced up the expansion tube due to excess temperature in the lower reservoir, it will be discharged in a generally downward direction.

Preferably the level of cold water in the upper reservoir is maintained at a predetermined level by water level responsive valve means which permits the inflow of cold water into the upper reservoir only if the level of water therein is below the said predetermined level.

Conveniently the valve means is a float operated valve such as is commonly employed in water cisterns and cold water storage tanks which have to be kept topped up by water from a water supply main.

The invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1 is a side elevation partly in section of a dual reservoir arrangement to which the invention may be applied,

Fig 2 is a similar view of another dual reservoir arrangement to which the invention may be applied, and Fig 3 is a similar view of a further dual reservoir arrangement to which the invention may be applied.

In Fig 1 a lower hot water reservoir 10 is supplied with water from an upper cold water reservoir 12 via a pipe 14. The reservoir 12 is kept topped up in a conventional manner from a cold water supply eg the cold water supply mains.

Heating means such as an electric powered immersion heater (not shown in Figs 1 & 2) heats the water in 10 and in the event of overheating and expansion occurring in 10, hot water is forced up vent pipe 16. A sleeve 18 surrounds the pipe 16 and as shown is spaced therefrom to create an annular air gap 20 to impede the transfer of heat from any hot water in 16 to the cold water in 12. Thermal insulation material 22 separates the two reservoirs. The lower end of the annular air gap 20 is closed off by the base wall of the upper reservoir 12.

The pipes 14 and 16 may be formed from metal or a plastics material which is resistant to the flow of heat therealong so as to further limit the transfer of heat from 10 to 12.

In accordance with the invention, although not shown, the sleeve 18 is formed from thermally insulating material and is in contact with the expansion pipe 16.

In Fig 2 an air gap 24 exists between the two reservoirs to impede the transfer of heat therebetween and the pipes 14 and 16 are secured to the upper reservoir by means of thermally insulating plastics material collars 26,28 respectively to impede transfer therebetween. In other respects Fig 2 is similar to Fig 1 and the same reference numerals have been employed.

Again although not shown, the sleeve 18 is formed from thermally insulating material and is in contact with the expansion pipe 16.

Fig 3 shows a different arrangement in which expansion pipe 16 is bent over at 30 to form an inverted U-bend to bring the discharge end beyond the sleeve 18. A float operated valve 32 and float 34 on an arm 36 is shown for controlling the flow of cold water from a supply main feed 38, and an immersion heater 40 is shown in the lower reservoir 10. The two reservoirs are separated by insulating material 42 although they may be separated alternatively by an air gap.

Heat transfer is further reduced by forming the pipe 14 from a plastics material.

A lid 44 covers the open end of the reservoir 12.

A temperature sensor is shown at 46 for connecting to an electrical circuit (not shown) for generating a control signal if the temperature of the water in 10 exceeds a given temperature and for controlling the current to the heater 40.

A second temperature sensor is shown at 48 detecting the if temperature of the water in 12 exceeds a different threshold such as 39 C, above which microbiological growth can occur of harmful organisms which can promote disease.

Claims

Claims 1. A water heater comprising upper and lower reservoirs in which cold water is stored in the upper reservoir for feeding the lower reservoir which contains water heating means, with an interconnecting passage for transferring cold water from the upper reservoir to the lower to maintain the level therein and an expansion pipe to permit heated water forced out of the lower reservoir by expansion to return to the upper reservoir, wherein the expansion pipe extends into and upwardly through the upper reservoir and means is provided to thermally separate the body of water in the upper reservoir from the expansion pipe extending upwardly through the upper reservoir, thereby to reduce the transfer of heat from the expansion pipe to the water in the upper reservoir, said means comprising a sleeve which surrounds the expansion pipe to at least the depth of the water in the upper reservoir and wherein the sleeve is formed from thermally insulating material and is in contact with the expansion pipe.
2. A water heater as claimed in claim 1 wherein the expansion pipe at least where it extends into the upper reservoir is formed from a material having low thermal conductivity relative to that of copper.
3. A water heater as claimed in claim I wherein a collar of a material having a low thermal conductivity relative to that of copper surrounds the expansion pipe where it extends through a wall of the upper reservoir, to separate the pipe from the wall.
4. A water heater as claimed in claim 3 wherein a similar collar of a similar low thermal conductivity material surrounds the feed pipe from the upper reservoir to the lower reservoir, around the pipe where it extends through a wall of the upper reservoir, to separate the pipe from the wall.

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5. A water heater as claimed in any of the preceding claims wherein the upper end of the expansion pipe is bent over to form an inverted U-bend, or is otherwise extended, so that if water is forced up the expansion pipe due to excess temperature in the lower reservoir, it will be discharged in a generally downward direction, clear of the sleeve.
6. A water heater as claimed in any of claims 1 to 5 wherein the level of cold water in the upper reservoir is maintained at a predetermined level by water level responsive valve means which permits the inflow of cold water into the upper reservoir only if the level of water therein is below the said predetermined level.
7. A water heater as claimed in claim 6 wherein the valve means is a float operated valve.
8. A water heater as claimed in claim 1 constructed arranged and adapted to operate substantially as herein described with reference to the accompanying drawings.