U.S. patent application number 10/828228 was filed with the patent office on 2005-10-27 for convection loop hot tub system.
Invention is credited to August, Stephen David.
Application Number | 20050235406 10/828228 |
Document ID | / |
Family ID | 35134895 |
Filed Date | 2005-10-27 |
United States Patent
Application |
20050235406 |
Kind Code |
A1 |
August, Stephen David |
October 27, 2005 |
Convection loop hot tub system
Abstract
There is provided a portable spa pool or hot tub system which
includes a tub suitable for human bathing, and a water heating unit
capable of burning one or more fuels. The water heating unit is
situated adjacent to the tub and connected to the tub through an
upper and a lower piping means, the arrangement forming a
convection circulation loop. The tub is optionally circular, and
when empty capable of being lifted and carried by two persons.
Optionally the tub is double skinned and of a rigid plastics
material with insulation between the two layers of plastic.
Inventors: |
August, Stephen David;
(Dunedin, NZ) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Family ID: |
35134895 |
Appl. No.: |
10/828228 |
Filed: |
April 21, 2004 |
Current U.S.
Class: |
4/493 |
Current CPC
Class: |
A61H 2201/0161 20130101;
A61H 2201/0157 20130101; A61H 33/0095 20130101; A61H 33/0087
20130101 |
Class at
Publication: |
004/493 |
International
Class: |
E04H 004/00 |
Claims
What is claimed is:
1. A portable spa pool or hot tub system comprising: a tub suitable
for human bathing, and a water heating unit capable of burning a
fuel selected from the group consisting of: solid fuel, diesel,
other petroleum product, and gas; said unit being situated and
adjacent to said tub and connected to said tub through an upper and
a lower piping means arranged such that water heated in the water
heating unit rises into the tub via the upper piping means and is
replaced by cooler water from the tub via the lower piping means,
the arrangement forming a convection circulation loop.
2. A system as claimed in claim 1 wherein said tub has a circular
side wall.
3. A system as claimed in either claim 1 wherein said tub is
constructed as a double skinned tub, with an insulating material
between the skins.
4. A system as claimed in claim 3 wherein the skins of the tub are
of a plastic material.
5. A system as claimed in claim 4 wherein the plastic material is
polyethylene.
6. A system as claimed in claim 3 wherein the insulating material
is a foamed polyurethane.
7. The system as claimed in claim 1 wherein the weight of the tub
is such that two persons of average strength can lift and carry
said tub, when empty.
8. The system as claimed in claim 1 wherein the rigidity of the tub
is imparted to the tub by use of a water-impermeable material and
the tub constructed in compartments which are capable of being
inflated.
9. A portable spa pool or hot tub system as claimed in claim 1
wherein the water heater comprises a water jacket and a combustion
chamber, the combustion chamber comprising a flame baffle plate and
an ancillary air delivery means providing oxygenated heated air to
the rear of the combustion chamber.
10. A portable spa pool or hot tub system as claimed in claim 1
wherein the water heater further comprises a primary access door
and a secondary access door, the secondary door being rotatable
about the longitudinal axis of the water heater.
11 A portable spa pool or hot tub system as claimed in claim 9
wherein the ancillary air delivery means comprises a tube located
through a hole in the primary access door.
12. A portable spa pool or hot tub system as claimed in claim 1
wherein said water heater further comprises a flue, said flue
having an outer guard and a fly ash screen within a cowl at the
upper end of the flue.
13. A portable spa pool or hot tub system as claimed in any one of
claims 9 wherein the inner surface of the combustion chamber is
corrugated.
14. A tub when used in a portable spa pool or hot tub system
wherein the system comprises a water heating unit capable of
burning a fuel selected from the group consisting of: solid fuel,
diesel, other petroleum product, and gas; said unit being situated
and adjacent to said tub and connected to said tub through an upper
and a lower piping means arranged such that water heated in the
water heating unit rises into the tub via the upper piping means
and is replaced by cooler water from the tub via the lower piping
means, the arrangement forming a convection circulation loop.
Description
TECHNICAL FIELD
[0001] This invention relates to hot tubs and spa pools.
BACKGROUND ART
[0002] Conventional spa pools or hot tubs work by continually
heating and recirculating water from the heating unit to the tub or
pool. In order to achieve adequate circulation, pumps are almost
invariably used to convey water from the heating unit to the pool
and back again--a forced loop circulation system. In almost all
designs, the pumps run on electrical power. Further, because pumps
continuously recirculate the same water for periods of weeks or
months, build-up of algae and bacteria needs to be stopped or
inhibited, usually by adding to the water chemical agents, e.g.
chlorine.
[0003] Additionally, conventional spa pools take many hours to heat
up to a usable temperature, and they are designed to be left filled
and heated for weeks. Therefore such pools have ongoing costs in
electricity and chemicals and ongoing time requirements from
monitoring chemical levels and changing filters, whether they are
being used or not. Also, the most commonly used disinfectant
chemical, chlorine, can irritate a range of skin conditions,
particularly eczema and psoriasis.
[0004] There are available freestanding conventional spa pools
which fill from a hose, and plug into a domestic electrical socket.
These are more portable than the built-in designs described above,
but are still heavy to shift manually and not robust due to their
complex electrical machinery. They are of course restricted to
sites with electrical outlets.
[0005] Although the word "portable" is commonly applied to patented
systems and/or selling descriptions of such units, the need for
electrical connections and motors means that the use of the word
`portable` in those contexts has definite limits. For example, an
electrically-dependant unit cannot be used in a remote outdoor
location without an electric power supply being provided. Further,
the weight and relatively fragile construction of such
electrically-dependant systems realistically precludes them from
being moved to such sites.
[0006] So called `portable` spas or tubs have been developed around
a number of differing but related principles. In U.S. Pat. No.
5,408,707 which describes a "portable" spa, the tub itself is
collapsible and has a pump with jets. This spa is described as
"portable" because the tub itself is "portable". However, the unit
utilizes a pump and therefore cannot be used without an
[electrical] power source. U.S. Pat. Nos. 6,108,829, 5,815,854,
4,843,659, 6,357,059, 6,003,166, 6,058,521, 4,744,112, 5,791,106,
and 6,412,123 all similarly describe a range of different spas and
tubs all of which utilize pumps and other electrical fittings for
pumped circulation and heating.
[0007] U.S. Pat. No. 4,621,613 describes a system for pool and spa
heating and attempts to incorporate the advantages of convection
loop flow into a complex heat exchange system whereby water is
heated in a heat exchanger and is then introduced near the bottom
of the pool or spa whereupon it rises to the surface.
[0008] All of the above patents employ the use of pumps and
therefore electricity. In the strict sense they are not truly
portable" units, as power is required at every location any prior
art unit is moved to. In some of the above cases the spas are
collapsible, and this then defines or limits the extent of their
"portability."
[0009] U.S. Pat. No. 4,455,997 (assignee Snorkel Stove Company)
does describe a different design, with an underwater burner heating
the water in a tub, which would not necessarily require an
electrical connection. However, this style of hot tubs has an
internal partition to separate off the underwater stove from the
bathers, which means they must be bigger than the earlier described
systems to fit the same number of bathers. Also the tubs are
disclosed as being made of wood, so that for the same number of
bathers they are heavy. In addition to these disadvantages their
wood construction makes them less robust. They would not survive,
for instance, being dropped on or rolled over rocky terrain.
Furthermore the Snorkel Stove Company website quotes "about 4
hours, honest!" as the time necessary to assemble their kitset
tub.
[0010] An additional disadvantage with wooden tubs, unless an
internal liner is added, is that they rely on the expansion of
water-absorbing wood against the restraining metal cooping bands to
force the staves tightly together to achieve water-tightness, which
can take days to fully occur.
[0011] Lastly, the water heating unit burns only wood, without the
capability to use gas or other fuels. This has obvious
disadvantages with respect to safety in, for instance, fire risk
conditions or environments.
[0012] All references, including any patents or patent applications
cited in this specification are hereby incorporated by reference.
No admission is made that any reference constitutes prior art. The
discussion of the references states what their authors assert, and
the applicants reserve the right to challenge the accuracy and
pertinency of the cited documents. It will be clearly understood
that, although a number of prior art publications are referred to
herein, this reference does not constitute an admission that any of
these documents form part of the common general knowledge in the
art, in New Zealand or in any other country.
[0013] It is acknowledged that the term `comprise` may, under
varying jurisdictions, be attributed with either an exclusive or an
inclusive meaning. For the purpose of this specification, and
unless otherwise noted, the term `comprise` shall have an inclusive
meaning--i.e. that it will be taken to mean an inclusion of not
only the listed components it directly references, but also other
non-specified components or elements. This rationale will also be
used when the term `comprised` or `comprising` is used in relation
to one or more steps in a method or process.
[0014] It is an object of the present invention to address the
foregoing problems or at least to provide the public with a useful
choice.
[0015] Further aspects and advantages of the present invention will
become apparent from the ensuing description which is given by way
of example only.
DISCLOSURE OF INVENTION
[0016] According to one aspect of the present invention there is
provided a portable spa pool or hot tub system including:
[0017] a tub suitable for human bathing, and
[0018] a water heating unit capable of burning a fuel selected from
the group consisting of: solid fuel, diesel, other petroleum
product, and gas; said unit being situated and adjacent to said tub
and connected to said tub through an upper and a lower piping means
arranged such that water heated in the water heating unit rises
into the tub via the upper piping means and is replaced by cooler
water from the tub via the lower piping means, the arrangement
forming a convection circulation loop.
[0019] According to another aspect of the present invention there
is provided a tub when used in a portable spa pool or hot tub
system wherein the system further includes a water heating unit
capable of burning capable of burning a fuel selected from the
group consisting of: solid fuel, diesel, other petroleum product,
and gas; said unit being situated and adjacent to said tub and
connected to said tub through an upper and a lower piping means
arranged such that water heated in the water heating unit rises
into the tub via the upper piping means and is replaced by cooler
water from the tub via the lower piping means, the arrangement
forming a convection circulation loop.
[0020] The tub is of a size and form able to hold up to several
human bathers. It may take the form of a rounded-edged double
skinned insulated cylinder wider than it is high. The convection
loop system employed also applies to more rectangular or convoluted
shapes of tubs. The tub may be constructed of a range of materials
but a preferred construction uses a foam spun plastic sandwich
which is extremely robust and allows the vessel to be rolled or
roughly handled.
[0021] The water heater/burner sits adjacent to the tub. It
incorporates a water jacket and is connected to the tub by two
hoses, the upper of which must rise at an incline from the burner
to the tub. When firewood or other solid fuel or diesel or other
suitable petroleum product or gas fire is lit in the burner, the
water in the water jacket is heated and rises through the upper
hose to the tub, being replaced by cooler water from the tub
running back to the burner via the lower hose. This forms a
convection loop which heats the tub water as the water continuously
circulates through the lit burner. It does not require a pump, nor,
therefore, electricity.
[0022] In the invention the traditional use of pumps is obviated by
achieving a relatively high rate of `convection circulation`. This
has been achieved by providing a reasonable circulation rate. The
rate of heating is related in part to the vertical distance between
the in and out ports to the hot tub, the insulation rating of the
tub itself, and heater features which include but are not limited
to corrugating the internal combustion chamber, which increases the
surface area available for heat exchange, and an internal baffle to
lengthen the flame trail for the same reason.
[0023] A very simple but efficient water heater design is used
which is able to burn smoklessly and which does away with the
complicated designs described in, for example, U.S. Pat. Nos.
4,501,232, 4,190,199 and 5,201,307, these designs being unsuitable
for truly portable systems as they are too heavy to move. The same
applies to any of the wooden tub designs. Invariably wooden
construction results in designs that are not light enough to be
moved by one person and which also lack the robustness necessary if
they are to withstand routine or regular transportation to
different sites.
[0024] In a preferred embodiment the system of the current
invention the tub comprises a rigid structure of spun plastic foam
core construction providing sufficient rigidity, lightness and
strength for the unit to be rolled or moved by one person, or
lifted and carried by two. The water heater is gas- or solid
fuel-heated and is a separate module, which can be carried
separately or stored for transport inside the tub.
[0025] As a result the tub/heater system is ideally suited for
domestic houses, holiday cabins or cribs, weekend use, back country
huts, beaches, boats, outdoor, and adventure use because no set-up
ancillary requirements are needed at the (remote) site. The tub is
adapted to be rolled along the ground by a single person, robust
enough to sustain being bounced over rocky terrain or dropped from
at least half a meter onto concrete without suffering structural
damage. It can also be lifted and carried by two persons, or even
floated and towed behind a boat. Assembling the system on site
takes less than two minutes.
BRIEF DESCRIPTION OF DRAWINGS
[0026] Further aspects of the present invention will become
apparent from the following description which is given by way of
example only and with reference to the accompanying drawings in
which:
[0027] FIG. 1: is an isometric view of the hot tub of the present
invention showing the water heater and a gas fuel supply.
[0028] FIG. 2 is an isometric view of the hot tub of the present
invention showing the heater, a gas fuel supply and burner
nozzle.
[0029] FIG. 3 is an isometric view of the hot tub of a preferred
embodiment of the present invention with the water heater part cut
away showing the inside of the burner, air supply and flame
baffle.
[0030] FIG. 4 is a cross sectional isometric of the hot tub of the
present invention; and
[0031] FIG. 5 is an isometric view of the upper port of the present
invention.
BEST MODES FOR CARRYING OUT THE INVENTION
[0032] FIG. 1 shows all of the basic components of a fully portable
hot tub system of the present invention. The `hot tub` comprises
the tub (1), a water heater (2), and a fuel supply. In FIG. 1 the
fuel supply is a 9 kg LPG gas bottle (3). However, it will be
appreciated by those skilled in the art that the fuel supply can be
selected from a range of solid fuels, with modifications to the
water heater (2), for example as described below.
[0033] The water heater (2) is shown with an exhaust flue (4) which
has an external perforated guard (5). Stabilizing legs (6) and (7),
screwed onto the rear of the water heater (2) ensure that the water
heater (2) remains upright when placed on the ground. The exhaust
flue (4) may be free standing in the sense that no external support
is required to stabilize the flue (4) other than the connection to
the water heater (2).
[0034] A convection loop is created between the tub (1) and the
water heater (2) by the interconnecting pipes (8) and (9). The
pipes (8) and (9) may be removed to permit transportation of the
system.
[0035] Large, easy to grasp handles (30, 31) are fixed on opposite
sides of the water heater (2) to enable it to be easily transported
by one or two persons.
[0036] A cowl (25) at the top of the exhaust flue (24) encloses a
fly ash screen (not shown) upon which a place (26) (dotted outline)
can be placed. The plate (26) may be used for cooking or heating
purposes, for example, by the use of a pot (27).
[0037] FIG. 2 shows a secondary access door (10) to the water
heater (2) in the open position. This allows a slotted gas burner
head (11) to be inserted into the heating compartment of the water
heater (2). The access door (10), which is mounted to a primary
access door (12), is fixed by a pivot pin (13) and is rotatable
with respect to the longitudinal axis of the water heater (2). The
pivot pin (13) allows the access door (10) to be rotated to expose
an opening in the primary access door (12). The primary access door
(12) is able to opened, with the use of hinges (14, 15) and has a
catch (16) for releasably securing the door (12) in a closed
position. The use of the primary and secondary access doors (10,
12) permits the use of more than one fuel.
[0038] FIG. 3 shows the water heater (3) part cutaway, revealing
inside a combustion chamber a gas burner head (11), a flame baffle
plate (17) and an ancillary air supply (18). The ancillary air
supply (18) provides fully oxygenated heated air to the rear
portion of the heating compartment of the water heater (2). An
outer water jacket (19) of the water heater (2) is also shown. The
flame baffle plate (17) optionally extends to the sides, and along
the bulk of the length, of the water burner (2). This arrangement
assists with heat transfer to the water in the water jacket, and in
reducing the flame length in the exhaust flue (4).
[0039] In a second embodiment, if a solid fuel (for example, wood,
coal) is to be burnt in the water heater (2), a grate (not shown)
can be inserted into the base of the water heater (2) in known
manner.
[0040] Optionally, for both embodiments, the interior of the water
heater (2), within the combustion chamber, is corrugated to assist
in heat transfer to the water.
[0041] FIG. 4 shows a cut away view of the tub (1) revealing upper
and lower access ports (20, 21) to the interconnecting pipes (8, 9)
respectively. The upper port (20) is covered with a grill (22)
which includes a floating disc (23). Referring to FIG. 5, the disc
(23) moves up and down with the variation of the water level in the
tub (1). The disc (23) moves over the port (20) when steam starts
to enter the tub (1), deflecting the steam laterally to the
interior of the tub wall. A stop (24) ensures the disc (23) settles
in the correct position after the tub (1) has been moved.
[0042] The tub (1) is preferably cylindrical in shape, with a
contiguous base. Optionally the cylindrical diameter is greater
than the height of the tub (1). The tub (1) can be made of a
plastics material, with the selection of the plastics being for
appropriate rigidity and robustness of the tub (1) when used or
moved. Optionally, the tub (1) is a double skin arrangement with an
insulating layer of material between the two skins. The tub (1) may
be of molded polyethylene, and the insulation a foamed core of a
second plastics material. Optionally, the second plastics material
is foamed polyurethane.
[0043] In an alternative embodiment, the necessary rigidity of the
tub (1) can be imparted to the tub (1) by use of water-impermeable
material and the tub (1) constructed in compartments which are
capable of being inflated to provide the required rigidity. A
suitable material for use in this embodiment is a polyvinylchloride
plastic.
[0044] The material, shape and core (if present) of the tub (1) are
sufficiently robust, and the tub (1) is sized so that the tub (1),
when empty, can be lifted and carried by two persons or rolled on
its side, by at least one person.
[0045] Whilst not shown in the drawings, it will be appreciated by
those skilled in the art that the tub (1) may be supplied with a
lid which fits over the tub (1) and be releasably secured to the
tub (1), when the tub (1) is not in use.
[0046] Aspects of the present invention have been described by way
of example only and it should be appreciated that modifications and
additions may be made thereto without departing from the scope
thereof.
* * * * *