ENDOTHERMIC BASE-MOUNTED HEAT PUMP WATER HEATER

CHAUFFE-EAU A POMPE A CHALEUR MONTE SUR UNE BASE ENDOTHERMIQUE

English Abstract

An endothermic heat pump water heater has a water tank supported atop a hollow base, a heat pump circuit operable to provide primary heat to water in the tank, and an electric resistance heating element operable to provide secondary heat to the water. The heat pump circuit includes refrigerant tubing in which a compressor disposed within the base, a condenser in heat exchange external contact with the tank, a refrigerant expansion device, and an evaporator disposed within the base are connected in series. A vertical duct, external to the tank, has an inlet adjacent the upper tank end, and a fan is operative to sequentially flow air inwardly through the inlet, downwardly through the duct into the base, across the compressor, across the evaporator, and then outwardly from the base.

French Abstract

Chauffe-eau à pompe à chaleur endothermique constitué dun réservoir deau soutenu au haut dune base creuse, dun circuit de pompe à chaleur fonctionnant de façon à acheminer une chaleur principale vers leau du réservoir et dun élément chauffant à résistance électrique fonctionnant de façon à acheminer une chaleur secondaire vers leau. Le circuit de pompe à chaleur comprend un tube réfrigérant dans lequel un compresseur disposé dans la base, un condenseur en contact externe pour léchange de chaleur avec le réservoir, un dispositif dexpansion du réfrigérant et un évaporateur disposé dans la base sont branchés en série. Une conduite verticale, externe au réservoir, comporte une entrée adjacente à lextrémité supérieure du réservoir. De plus, un ventilateur fonctionne de façon à acheminer de façon séquentielle lair vers lintérieur, par lorifice dentrée, puis vers le bas à travers la conduite et jusquà la base en passant par le compresseur et lévaporateur, pour finalement sécouler vers lextérieur à partir de la base.

Claims

WHAT IS CLAIMED IS:
1. A water heater comprising:
a hollow base;
a tank adapted to hold a quantity of water to be heated, said tank having
upper and lower
ends and being supported atop said base;
a heat pump circuit operable to provide primary heat to water in said tank,
said heat pump
circuit comprising refrigerant tubing in which (1) a compressor disposed
within said base, (2) a
condenser in heat exchange contact with said tank, (3) a refrigerant expansion
device, and (4) an
evaporator disposed within said base are connected in series in a manner such
that said
compressor is operative to flow refrigerant sequentially through said
condenser, said expansion
device, and said evaporator and then back to said compressor via said
refrigerant tubing;
a duct, external to said tank, through which air flows into said base;
a fan operative to sequentially flow air through said duct into said base,
across said
compressor, across said evaporator, and then outwardly from said base and
secondary heating apparatus operable to heat water in said tank.
2. The water heater of Claim 1 wherein:
said secondary heating apparatus includes a resistance type electric heating
element
extending through the interior of said tank.
3. The water heater of Claim I wherein:
said condenser is disposed externally of said tank.
4. The water heater of Claim 3 wherein:
said condenser is a condenser coil defined by a length of said refrigerant
tubing coiled
externally around said tank.
5. The water heater of Claim 4 wherein:
said condenser coil extends around only a lower portion of said tank.

6. The water heater of Claim 1 wherein:
said duct has an air inlet opening disposed at an elevation substantially
greater than that
of said lower end of said tank.
7. The water heater of Claim 6 wherein:
said duct is vertically elongated, with said air inlet opening being adjacent
said upper end
of said tank, and has a lower end, adjacent said base, through which the
interiors of said duct and
said base communicate.
S. The water heater of Claim 7 wherein:
said base has an air outlet opening therein which is generally opposite from
said lower
end of said duct, with said evaporator being inwardly adjacent said outlet
opening of said base,
and said compressor being inwardly adjacent said lower end of said duct.
9. The water heater of Claim 1 wherein:
said fan is an evaporator fan disposed within said base.
10. The water heater of Claim 1 wherein:
said refrigerant expansion device is disposed within said base.
11. The water heater of Claim 1 wherein:
said evaporator is a vertically oriented panel type evaporator coil.
12. The water heater of Claim 1 further comprising:
a control system operative to selectively energize said secondary heating
apparatus and/or
said heat pump circuit.
6

13. A water heater comprising:
a hollow base having a top side and a periphery extending downwardly from said
top
side, said periphery having horizontally oppositely disposed air inlet and air
outlet openings
extending therethrough;
a tank adapted to hold a quantity of water to be heated, said tank having
upper and lower
ends and being supported atop said base;
a heat pump circuit operable to provide primary heat to water in said tank,
said heat pump
circuit comprising refrigerant tubing in which (1) a compressor disposed
within said base
inwardly adjacent said air inlet opening therein, (2) a condenser coil defined
by a length of said
refrigerant tubing externally wrapped around a lower portion of said tank in a
heat exchange
relationship therewith, (3) a refrigerant expansion device, and (4) an
evaporator coil disposed
within said base inwardly adjacent said air outlet opening therein are
connected in series in a
manner such that said compressor is operative to flow refrigerant sequentially
through said
condenser, said refrigerant expansion device. and said evaporator and then
back to said
compressor via said refrigerant tubing;
a vertically elongated duct disposed externally adjacent said tank, said duct
having an
upper end portion disposed adjacent said upper end of said tank and having an
air inlet opening,
and a lower end portion disposed adjacent said air inlet opening of said base
and communicating
the interior of said duct with the interior of said base through said air
inlet opening of said base;
an evaporator fan disposed within said base between said compressor and said
evaporator
and being operative to sequentially flow air into said air inlet opening of
said duct, downwardly
through said duct into said base, across said compressor, across said
evaporator, and then
outwardly from said base through said outlet opening therein;
a resistance type electric element extending through the interior of said tank
and being
energizable to provide secondary heat to water in said tank; and
a control system operative to selectively energize said electric heating
element and/or
said heat pump circuit.
7

14. A method of heating water comprising the steps of:
providing a hollow base;
positioning a tank atop said base, said tank having upper and lower ends;
providing a heat pump circuit having refrigerant tubing in which a compressor
,
condenser, refrigerant expansion device and evaporator are connected in
series;
disposing said compressor and said evaporator in said base;
placing said condenser in external, heat transfer contact with said tank;
energizing said heat pump circuit to cause said compressor to sequentially
flow
refrigerant to said condenser, said refrigerant expansion device and said
evaporator and then
back to said compressor; and
flowing air, via a path external to said tank, from an elevation substantially
higher than
that of said lower end of said tank sequentially into said base across said
compressor, across said
evaporator, and then outwardly from said base.
15. The method of Claim 14 wherein:
said condenser is a condenser coil, and said placing step is performed by
coiling a length
of said refrigerant tubing externally around said tank to form said condenser
coil.
16. The method of Claim 15 wherein:
said placing step is performed by coiling a length of said refrigerant tubing
externally
around only a lower portion of said tank to form said condenser coil.
17. The method of Claim 14 wherein:
said flowing air step includes positioning a vertically elongated duct
adjacent a vertical
side portion of said tank and flowing the air downwardly through an upper end
portion of the
duct into said base.
8

Description

CA 02815500 2013-04-25
ENDOTHERMIC BASE-MOUNTED HEAT PUMP WATER HEATER
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to water heaters and, in a
representatively
illustrated embodiment thereof, more particularly provides a specially
designed endothermic heat
pump water heater.
[0002] Water heaters incorporating, as a heat source, a heat pump circuit in
addition to a fuel-
fired or electric resistance type water heating system are known in the water
heating art. While
the heat pump circuit, due to its high thermal efficiency, has typically been
viewed as a useful
addition to conventional water heating apparatus such as electrical resistance
heating elements, it
has been seen as desirable design goal to improve in water heating
applications various
characteristics of conventionally constructed heat pump circuits. Such desired
improvements
include increasing the reliability and thermal efficiency of such heat pump
circuits, reducing
their noise generation, and reducing undesirable heat transfer from the water
heater tank to
cooled air flow created by operation of the heat pump circuit. It is to this
design goal that the
present invention is primarily directed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 is a perspective view of the water heater;
[0004] FIG. 2 is a partially cut away perspective view of the water heater;
[0005] FIG. 3 is a schematic circuit diagram of a heat pump circuit portion of
the water heater;
[0006] FIG. 4 is an enlarged scale, partially cut away schematic side
elevational view of the
water heater; and
[0007] FIG. 5 is a schematic block diagram of a representative control system
for the water
heater.
DETAILED DESCRIPTION
[0008] With reference initially to FIGS. 1, 2 and 4, the present invention
provides a specially
designed endothermic base-mounted heat pump water heater 10 having a
vertically elongated
cylindrical metal tank 12 enclosed within an insulated metal jacket structure
13 and mounted
atop a hollow cylindrical base 14 having a circumferentially spaced plurality
of support members
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CA 02815500 2013-04-25
16 spaced around its periphery. A quantity of pressurized water 18 to be
heated is stored within
the interior of the tank 12 for on-demand delivery to a variety of hot water-
utilizing plumbing
fixtures such as sinks, tubs, dishwashers, showers and the like, via a hot
water outlet 20 from the
upper end of the tank 12 (see FIG. 4) or a hot water outlet (not shown) from
an upper side
portion of the tank 12. Hot water withdrawn from the tank in this manner is
automatically
replaced by pressurized cold water received from a suitable source, such as a
municipal water
supply, via a cold water inlet 22 on the upper end of the tank 12 (see FIG. 4)
or a cold water
inlet (not shown) at a bottom side portion of the tank 12.
[0009] In addition to a subsequently described specially designed heat pump-
based primary
water heating source, to heat the water 18 the water heater 10 is provided
with a secondary
source of heat - illustratively electric heat - via one or more immersion type
electric heating
elements 24 extending as shown through the interior of the tank 12.
Alternatively, the secondary
heating source could be a fuel-fired source or another type of non-heat pump
based secondary
water heating source. A suitable temperature sensor, such as a thermostat 26,
is utilized to
control the heating element 24.
[0010] For purposes later described herein, a vertically elongated duct 28
extends externally
along the tank jacket 13 and has a closed upper end 30 adjacent the upper end
of the water heater
10, and a closed lower end 32 adjacent the bottom end of the water heater 10.
Air intake grilles
34 are positioned on opposite sides of the upper duct end 30, an outlet
opening 36 in the lower
duct end 32 communicates with the interior of the base 14, and an air outlet
grille 38 is disposed
in a side wall portion of the base 14 opposite the duct opening 36.
[0011] Turning now to FIG. 3, a refrigerant-based heat pump circuit 40 is
uniquely
incorporated into the water heater 10 to provide it with an energy efficient
primary source of
water heating. Circuit 40 includes a compressor 42, a condenser coil 44, a
refrigerant expansion
device 46 (representatively in the form of an expansion valve) and a flat
panel evaporator coil 48
with an associated motor-driven evaporator fan 50, connected in series as
shown in refrigerant
tubing 52. During operation of the circuit 40, refrigerant flows through the
tubing 52 in the
direction indicated by the tubing flow arrows in FIG. 3.
[0012] Returning to the FIG. 4 schematic view of the water heater 10, the
compressor 42 is
disposed within the hollow base 14 inwardly adjacent the duct outlet opening
36, and the
expansion device 46 and evaporator coil 48 are positioned inwardly of the base
outlet grille 38
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CA 02815500 2013-04-25
across from the compressor 42. As illustrated, the condenser coil 44 is
defined by tubing 52
wrapped around and contacting the tank 12, illustratively a lower end portion
thereof, underneath
the jacket structure 13.
[0013] During operation of the heat pump circuit 40, the evaporator fan 50
sequentially draws
ambient air 54 adjacent the water heater 10 sequentially into the air intake
grilles 34,
downwardly through the external duct 28, into the interior of the base 14
through the duct outlet
opening 36, and across the compressor 42 to cool it. The evaporator fan 50
then sequentially
forces the air 54 across the evaporator coil 48 and outwardly through the
outlet grille 38 at the
bottom of the water heater 10. Another suitable type of fan could be utilized
to move the air 54
from the top of the water heater 10 through the interior of the base 14 if
desired. Refrigerant heat
from the condenser coil 44 is transferred to the tank water 18 through the
tank 12, and the air 54
is cooled by the evaporator coil 48 before being flowed out of the interior of
the base 14 through
the grille 38. Heat transfer from the condenser coil 44 to the tank 12 may be
enhanced by
suitably flattening the portion of the tubing 52 forming the coil 44 and/or
utilizing a suitable
thermal paste between the coil 44 and the tank 12.
[0014] Operation of the electric heating element 24 (see FIG. 4) and the heat
pump system 40
(see FIG. 3) is regulated as a function of the tank water temperature, as
illustratively sensed by
the thermostat 26, by a schematically depicted control system 56 shown in FIG.
5. Control
system 56 is respectively connected to the electric heating element 24, the
thermostat 26 and the
heat pump system 40 by control leads 58, 60 and 62. The control system 56,
which forms no
part of the present invention, automatically energizes the heating element 24
and/or the heat
pump system 40, in a suitable manner as needed to maintain the tank water 18
at a predetermined
temperature.
[0015] The unique design of the water heater 10 provides a variety of
advantages over
conventionally configured heat pump-enhanced water heaters. For example, since
the condenser
coil 44 is disposed at a higher elevation than the compressor 42, oil return
to the compressor
from the condenser coil 44 is gravity-driven, thereby improving compressor
reliability and heat
exchange. Additionally, the elevation of the air intakes 34 to adjacent the
top of the water heater
desirably provides the ability to remove more heat from the air 54 traversing
the heat pump
system compared to, for example, taking the air 54 from floor level. The
evaporator fan-driven
air flow through the water heater base 14 cools the compressor 42 and supplies
even warmer air
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CA 02815500 2014-10-22
to the evaporator coil 48. Further, the raised tank orientation reduces
undesirable heat transfer
from the tank to the cooled air 54 discharged from the water heater base 14.
Moreover, the
noise-generating heat pump components 42,50 are isolated within the base 14,
thereby reducing
the operating noise of the water heater 10 when the heat pump circuit 40 is
operating.
10016] Although the above has been described with reference to certain
specific embodiments,
various modifications thereof will be apparent to those skilled in the art
without departing from
the scope of the claims appended hereto.
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Representative Drawing