FIELD OF THE INVENTION
The present invention relates to a plastic electric water geyser which is also corrosion resistant. More particularly, the present invention relates to a light weight multi-function geyser having two-piece, injection-molded polymer inner tank and cover/ flange assembly. The present invention also relates to a method of manufacturing a plastic electric water geyser.
BACKGROUND OF THE INVENTION
Various different types of water geyser assemblies are known. Such assemblies are
predominantly formed from metal, and are prone to rust. Sacrificial anodes merely serve to
delay rather than to solve the rust problem.
Various fibre reinforced plastics material, and in particular glass fibre reinforced plastics materials have in the past been used with a view to overcoming the rust problem, such as the geyser disclosed in South African patent 82/6865. A problem associated with pressurized geysers of this type is that zones of weakness tend to develop, in particular at the interface between the geyser and the geyser fittings.
A water geyser assembly with an inner pressurizable container, and an outer shell both formed from a glass fibre reinforced plastics material disclosed in US patent 6070807. A polyurethane foam material fills the void defined between the inner container and the shell. A fitting mounting land formed with a number of apertures is provided at one end of the inner container for receiving fittings in the form of a pair of flanged spigot portions which are externally threaded and which are bridged at the flange. The flange locates against an inner surface of the fitting mounting land via sealing rings, and lock nuts are screwed down over each of the threaded spigot portions which project through the apertures so as to form a pressure tight fit. The fittings are thus locked mechanically to the mounting land without being laid in glass fibre during manufacture. Water inlet and outlet conduits, a heating
element assembly and a pressure relief valve are in turn mounted in communication with the spigot portions.
Prior to invention the inner assembly of water heaters for storing and heating water are made of corrosion resistant non-ferrous metals like copper, stainless steel and brass. In the conventional water geysers with metallic inner assembly, metal being good conductors of heat and electricity, additional insulations like glass wool or PUF (poly urethane foam) to minimize the heat loss has to be used. Moreover metals being good conductors of electricity, there are chance of electric leakage in hot water from conventional water geysers.
In hard water or water with salts, when water is heated in the conventional water geysers, scale formation occurs in the storage containers and in-out metallic pipes causing choking and thus increasing the risk of high pressure development in the internal assembly of the water heater which may cause bursting of the metallic tanks of the conventional water geysers. To minimize this risk safety devices like pressure release valve and drain pipe are fitted but being metallic they also usually fail due to choking caused by scaling deposits after a few years of usage.
Typically the conventional metal water geysers are manufactured by sheet metal processing which is cumbersome and time consuming. Presently polymers are being used to make the outer casing of the conventional metal water heaters but not for the inner tank assemblies so far because most polymers have a melting point around 70-80°C whereas temperature inside the water heater can go upto100°C. So if a container made of such polymer is used, it would melt down when water is heated beyond 70-80°C.
SUMMARY OF THE INVENTION
The present polymer electric geysers have two-piece, plastic injection-molded poly-
phenylene oxide inner tanks that never rust. The inner container of present polymer geyser
can stand a temperature of more than 120°C, is non-conductive and seals heat almost
much longer as compared to metallic containers. Even the mounting of heating element and
water inlet and outlet pipes are made of strong engineering-plastic which in addition to conserving heat are shock-proof too. The present polymer geyser is light but very strong and tough. It has a unique installation system due to which in spite of being fixed at one location it can be moved to another location where there is need for hot water.
The main properties and advantages of the end product over the available prior arts are as follows:-
Polymers being good insulators of heat, even if no separate insulation on the inner polymer assembly is used, the heat loss from the water heater is minimal.
Polymers are bad conductors of electricity. Consequently, use of polymer for the internal assembly of water heaters makes them very safe from electric leakage, almost shock-proof.
Polymers are resistant to scale formation and when used for internal assemblies of water heaters, problem of scaling is considerably reduced thus avoiding choking of pipes and making the water heater safer, longer lasting and more efficient.
A polymer container would not burst like a metallic container when the auto cut-off thermostat fails. It would only get ruptured after melting down when the temperature inside the container increases beyond the melting point of the polymer and the steam formed inside would escape gently without causing any accident.
Polymers being 6-8 times lighter than metals, the inner assembly made in polymer is lighter in weight than metallic one, thus it makes the water heater light and handy.
Process of polymer molding is faster and less cumbersome than sheet metal fabrication and hence large quantities of polymer inner assembly and hence the water heaters can be produced quickly saving time and labour.
OBJECTIVES OF THE INVENTION
It is an object of the present invention to overcome the drawbacks of the prior art.
It is an object of the present invention to provide an all-polymer, light weight multi-function geyser which is also corrosion resistant.
It is an object of the present invention to provide an all-polymer geyser which can be easily converted into storage water heater.
It is an object of the present invention to provide an all-polymer geyser which can provide instant supply of hot water.
It is an object of the present invention to provide an all polymer geyser that is energy efficient as well as safe from electric leakage, almost shock-proof.
It is an object of the present invention to provide a method for manufacturing an all-polymer geyser.
It is an object of the present invention to provide a method for replacing metallic (copper or stainless steel) inner container assembly used in the conventional electric water heaters with a polymer inner container assembly.
It is an object of the present invention to provide a plastic electric geyser with two-piece inner container assembly made of a special polymer compound which can stand a temperature of more than 120°C.
It is yet another object to provide a method for making polymer inner tanks of the plastic electric geyser by moulding a special polymer compound into the shapes of the water heater inner container and its cover/ flange with pipes by the process of injection moulding using moulds for the same.
It is yet another object of the present invention to provide a plastic electric geyser in which the special polymer used for making inner container assembly is poly-phenylene oxide.
A further object of the present invention is to provide a plastic electric geyser which can seal heat of hot water even without additional insulating layers of insulating materials like glass wool or PUF (poly urethane foam) to surround the inner container assembly of the electric water heater.
A still further object is to provide a plastic electric geyser in which the problem of scaling is considerably reduced thus avoiding choking of pipes and making the water heater safer, long lasting and more efficient.
A still further object of the present invention is to provide a plastic electric geyser which is less expensive, time saving and labor efficient to manufacture than the previous similar constructions.
Further objects and advantages of the present invention would be apparent from the following description and appended claims, reference being made to accompanying drawings forming a part of the specification which shall be accompanied with the complete specification.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of a plastic electric geyser assembly of the invention and the polymers used therein contains the properties of the descriptions mentioned below in tables.
Table: 1
(Table Removed)

We claim:
1. Aplastic electric water geyser comprising:
(a) two-piece inner container assembly made of a special polymer compound which can stand a temperature of more than 120°C and
(b) the accessories including a water inlet conduit, a water outlet pipe, and a heating element assembly.

2. A geyser as claimed in claim 1 wherein the special polymer used for making inner container assembly is poly-phenylene oxide.
3. A method of manufacturing a plastic electric water geyser assembly comprising the steps of:

(a) replacing metallic inner container assembly used in the conventional electric water heaters with a polymer inner container assembly,
(b) two-piece inner container assembly made of a special polymer compound which can stand a temperature of more than 120°C ,
(c) wherein making polymer inner tanks of the plastic electric geyser by moulding a
special polymer compound into the shapes of the water heater inner container and its
cover/ flange with pipes by the process of injection moulding using moulds for the
same,
(d) the special polymer used for making inner container assembly is poly-phenylene
oxide,
(e) wherein seal heat of hot water even without additional insulating layers of insulating materials like glass wool or PUF (poly urethane foam) to surround the inner container assembly of the electric water heater.
4. A method as claimed in claim 3 wherein plastic electric geyser easily converted into
storage water heater and provide instant supply of hot water.
5. A geyser as claimed in claim 1 wherein an all-polymer, light weight multi-function geyser which is also corrosion resistant, energy efficient as well as safe from electric leakage, almost shock-proof and the problem of scaling is considerably reduced thus avoiding choking of pipes and making the water heater safer, long lasting and more efficient.