Note: Descriptions are shown in the official language in which they were submitted.
rrhis lnvention relates to improvements in or relating
to boiling water dispensers which hea-t water to boiling point,
store the water at boiling temperatures and allow boiling
water to be periodically drawn off and replenished without
causing undue cooling of the remaining boiling water.
Conventional water heaters suffer from the disadvantage
that, as the wa-ter in the heater is removed, the heater has to
be replenished with cold water which then mixes with the
boiling water within the heater to cause a sudden drop in
temperature of the remaining water in the heater~ Liquid
storage and heating units have also been proposed in which a
cold water tank is separated from the area of the tank
con-taining the hot water so that addition of further cold
water does not have the e~fect of reducing the temperature
of all the water within the tank. However, a problem that
can be frequently encountered with such equipment is that the
interior of the e~uipment can become clogged with scale and
other contamlnants which ma.y enter with the watex supply.
It is an object of the present invention to provide an
~0 im~roved boiling water dispenser.
According to the present invention there is pr~videa
a boiling water dispenser comprising a tank for cold water
in fluid communication with a boiling chamber, said boiling
chamber being positioned within a tank for hot water and
having means to boil the water, the boiling chambex having an
upwardly extending expansion pipe which is arranged i.n use to
feed the boiling water to the hot tank only when the water
boils in the boiling chamber,- and an outlet positioned in the
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hot tank to ~llow boiling wa-ter to be dispensed from the
dispenser, the water within the hot tank being maintained
at boiling temperature due to conduction of hea-t from the
heating means through the boiling chamber~
Preferably the free end of the expansion pipe
terminates at a level above the normal static level of water
in the cold water tank so that water only escapes to the hot
water tank by percolating over the free end of the expansion
pipe due to boiling in the boiling chamber. The cold water
tank is preferably positioned above the hot water tank and
the boiling chamber comprises a glass enclosure fed at one
end by a conduit from the cold water tank and having the
e~pansion pipe extending upwardly from the opposite end.
In a preferred embodiment a primary heating elemen-t
and a pilot heating element are positioned within the boiling
chamber. A primary switching means is provided to sense the
level of boiling water in the hot tank so that at a predetermined
level the primary heating element is cut off leaving only the
pilot element to maintain the water within the hot tank at
boiling tem erature. A secondary switching means may also be
provided to switch off both hea-ting elements in the event of
water within the cold water tank ~alling below a predetermined
level.
Preferably a condenser is provided to condense steam
produced by the boiling chamber to water which is returned to
the hot or cold water tank. The condenser preferably comprises
a primary condenser formed in the lid of the dispenser and in
fluid communica-tion with an enclosure positioned adjacent the
free end of the expansion pipe, the steam condensing to water
in the lid, which water falls back into the enclosure
surrounding the expansion pipe and from there into the hot
water tank.
In a preferred embodiment the secondary condenser
comprises a conduit extending from the primary condenser
down onto a plate located slightly above the full level of
water in the cold water tank so that steam not condensed in
the primary condenser passes down -the conduit onto the plate
and is condensed to water which then falls into the cold
water tank.
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The present invention will now be described with
reference to the accompanying drawings in which:
Figure 1 is a perspec-tive view of a boiling water
dispenser in accordance with the present invention; and
Figure 2 is a perspective view of an upper part of
the dispenser illus-trated in Figure 1.
A boiling water dispenser as illustrated in Figures
1 and 2 comprises an ou-ter rectangular ca~ing 20 having a base
21 and enclosed by a rectangular lid 22. Within the upper
part of the casing 20 there is located a rectangular cold wa-ter
tank 23 which is fed with cold water viaan inlet pipe 24 and
controlled by a conventional float valve 25. A hot water tank
26 is located beneath the cold water tank 23 and is bordered
by the base of the outer casing 21 and insulating wall portions
27. An outlet pipe 28 which may be in the form of a ~ispensing
tap (not shown) is position2d in the base of the container to
allow hot water -to be released from the hot tan~ 26.
Within the lower part of the hot water tank 26 is
located a boiling chamber 31 which comprises a copper cylinder
32 mounted with its axis horizontal and arranged to contain a
pair of electrical heating elements 34 and 35 which are secured
at one end in one end face 37 of the cylinder. The end face
37 of the cylinder is connected to the base of the cold water
tank 33 via a conduit 38 which extends through the side wall
27 of the hot water tank. The opposi-te end 40 of the boiling
chamber 31 is provided with a vertically ex-tending expansion
pipe 42 which extends up through the hot water tank 26 and
terminates within an open ended cylindrical enclosure ~3 which
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is ].ocated in an inverted fashion over the end ~4 of the
expansion pipe 42. The end 44 of expansion pipe 42 is arranged
to be above -the full level of water in the cold water tank 23.
The level of water in the cold water tank is controlled by the
ball valve 25 and an overflow pipe 48 is also provided to ensure
against overfilling of the cold water tank due to breakdown of
the float valve.
To operate the dispenser the tank 23 is filled with
cold water via the inlet 24 and this cold water pours into
the boiling chamber 31 via the conduit 38 and up the expansion
pipe 42 to find a static level which is common with the level
in the cold water tank. At this stage the hot water tank is
effectively sealed from the boiling chamber 31 and is empty
because the free standing level of the water in the expansîon
pipe 42 is below the upper end 4a of the pipe. If the power
is then swi~ched on tne electrical heating elements 34 and 35
heat the water within the boiling chamber and the hot water
circulates to the top of the expansion pipe q2. Eventually the
water within the boiling chamber boils and this has the effect
of causing the level in the expansion pipe to rise until the
water cascades (arrowed in Figure 1) over the upper end ~4 ana
down within the enclosure 43 to fall into the base of the hot
water tank 26. The water which falls in the hot water tank
26 is maintained in a-boiling condition by heak from ~he heating
elements 34 and 35 which lS conducted through the brass walls
of the boiling chamber 31.
As boiling water percolates from the boiling chamber 31
via the expansion pipe 42 it is replenished with cold water at
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the opposite end 37 of ~he chamber 31 via the conduit 38
connected to the cold water tank 23. Eventually the hot water
tank becomes full of boilin~ water to a level at which the
boiling wa-ter enters a sealed cylindrical enclosure 50 positioned
in the cold water tank and fed via a conduit 51 ~hich extends
into the hot water tank 26 as shown in Figure 1. A float 53
is provided in this sealed chamber 50 so that as the hot water
enters this chamber the float is lifted to actuate by til~ing
a first mercury switch 54 via an arm and spring arrangement 55.
Actuation o the first mercury switch 54 causes the power to be
cut off from the primary heating element 35 thereby maintaining
the pilot element 34 to maintain the water in the hot ~ank at
boiling tempera-ture bu-t not causing boiling water to be
ejected from the expansion pipe 42~. When in this condition the
dispenser contains a full tank of boiling ~ater which can be
drawn ofE from the outlet 28 whilsl: at the same time contains
cold water in the cold water tank to replenish any boiling
water which may be periodically removed.
As boiliny water is dispensed via the outlet 28, the
: 20 level in the sealed enclosure 50 drops and accordingly the
float 53 re-actuates the mercury switch 54 to allow the heating
element 35 to operate thereby causin~ further percolation of
boiling water out of the expansion pipe to top up the hot water
tank.
The dispenser also includes a safety device to ensure
that neither heating element will operate in the event o~
failure of the cold water supply. A cylindrical enclosure 60
is located adjacent the inlet 2~ of the cold water tank and
is provided wi-th a float 61 connected via an arm and spring
arranyem2nt 62 to a second mercury switch 63. If the level
oE cold water within the scaled chamber 60 drops below a
predetermined level, the floa-t sinks to a level at which the
secondary mercury switch is closed cut-ting off all power to
both heating elements 34 and 35 and -therefore ensuriny against
damage to the heating elements. The enclosure 60 surrounding
the float 61 is provided to ensure that water entering the
cold water tank does not cause undue turbulence of the ~loat
61.
Another feature of the boiling water dispenser is
provision of primary and secondary condensers in the roo~ of
the unit to ensure that steam generated by the boiling chamber
31 is condensed into water which is returned to hot water and
cold water tanks. As shown in Figure 1 the enclosure 43 of
the expansion pipe 42 terminates a-t one end into an outlet
pipe 70 which is connec-ted to the lid 22 of the container via
a pipe 71~
~i~ure 2 is an illustrat:ion of the cold water tank and
lid assembly 22 and illustrates the primary and secondary
condensers. The rectangular lid 22 is constructed of copper
and has a metal base 81 which locates upon a ledge 82 provided
in the top of the cold water tank 23~ The pipe 71 ~eeds the
steam from the enclosure 43 into a chamber defined by the roo~
80 constituting the primary condenser within the space enclosed
within the lid 22. As the steam which escapes from the
expansion pipe ~2 passes up the pipe 70 and into the primary
condenser via the pipe 71, the majority of the steam condenses
into water droplets which collect on the base plate 81 and pour
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back down the pipe 71 into the enclosure 43 and from there
into the ho-t water -tank.
However, some steam may not condense into droplets
and this steam escapes from the primary condenser via a pipe
85 down onto a small brass plate 86 located in the side wall
of the cold water tank 23 adjacent the upper level of cold
water and constituting the secondary condenser. The cold
water has the effect of reducing the temperature o the brass
plate 86 so that any remaining steam which does descend the
pipe 85 immediately condenses into droplets which fall of~ the
plate 86 into the cold water tank.
The provision o:E dual condensers ensures that there
is no escape of steam from the dispenser and the secondary
condenser particularl~ ensures that the steam does not
circula-te within the cold water tank to a) raise the temperature
of the cold water; and b) affect the sensiti~e mercury switches~
The dispenser described above is capable of ~uickly
producing boiling water because a small quantity o water is
initially heated to boiling point in the comparatively small
boiling chamber. The dispenser is also capable of storing
boiling water in the hot water tank whils-t using only a pilot
element 34. As boiling water is drawn off the dispenser, cold
water does not enter the hot water chamber but enters the
boiling chamber and therefore the temperature in the hot water
tank should not drop below boiling point. Furthermore~ various
safety devices ensure that there is no dangex that the elements
will burn out due to water failure or that overflow of either
the hot or cold water tank can take place. The dual condensers
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ensure there is no escape of steam so that the device can be
used withln a room wi-thout danger of escaping steam damaging
room furnishlngs. Since -the cold water is fed into a cold
water tank any sedimen-t or scale that may enter via the cold
water inlet settles in the base of the tank and is unlike
to be fed into the boiling chamber and hot water tank.
If the dispenser is switched off with water in the
hot water tank and then switched on again when the water has
cooled, the cold water can be drained rom the hot tank thereby
causing the primary element to operate to quickly produce
boiling water.
The dispenser described above may simply be mounted on
a wall, plugged into a supply o-f electricity and mains water
to produce a completely automatic, economical and eficient
boiling water dispenser which is both clean, safe and very
hygenic. Not only can boiling water be quickly produced but
the hot water tank is sufficiently large to cater for a
substantial demand without a drop in temperature of the water
output. The dispenser is considered particularly useful for
schools, restaurants and hotels where boiling water is frequently
required in varying quantities at periodic intervals.
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