U.S. patent application number 13/211890 was filed with the patent office on 2013-02-21 for heat pump water heater in conjunction with gas water heater.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is Michael Thomas Beyerle, Susan Elizabeth Gregory, Michelle Gross, Jonathan D. Nelson. Invention is credited to Michael Thomas Beyerle, Susan Elizabeth Gregory, Michelle Gross, Jonathan D. Nelson.
Application Number | 20130042635 13/211890 |
Document ID | / |
Family ID | 47711645 |
Filed Date | 2013-02-21 |
United States Patent
Application |
20130042635 |
Kind Code |
A1 |
Nelson; Jonathan D. ; et
al. |
February 21, 2013 |
HEAT PUMP WATER HEATER IN CONJUNCTION WITH GAS WATER HEATER
Abstract
A method for heating water delivered and stored in a water
heater storage tank includes activating at least one of dual fuel
heater types in response to various modes of operation. The water
heater is preferably a dual fuel or hybrid heat pump gas water
heater that includes a heat pump as the first type of heater for
heating the water, and a gas burner as the second type of heater
that transfer heat to the water. One or more sensors monitor water
temperature and communicate with a controller to activate one of,
or both of, the first and second types of heaters. If there is an
electrical power outage, the hybrid heat pump gas water heater is
still able to heat the water.
Inventors: |
Nelson; Jonathan D.;
(Louisville, KY) ; Beyerle; Michael Thomas;
(Peewee Valley, KY) ; Gregory; Susan Elizabeth;
(Louisville, KY) ; Gross; Michelle; (Louisville,
KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nelson; Jonathan D.
Beyerle; Michael Thomas
Gregory; Susan Elizabeth
Gross; Michelle |
Louisville
Peewee Valley
Louisville
Louisville |
KY
KY
KY
KY |
US
US
US
US |
|
|
Assignee: |
General Electric Company
|
Family ID: |
47711645 |
Appl. No.: |
13/211890 |
Filed: |
August 17, 2011 |
Current U.S.
Class: |
62/79 ;
62/238.7 |
Current CPC
Class: |
F24H 4/04 20130101; F24H
9/2021 20130101; F24H 9/2035 20130101; F24H 1/205 20130101 |
Class at
Publication: |
62/79 ;
62/238.7 |
International
Class: |
F25B 29/00 20060101
F25B029/00 |
Claims
1. A water heater, comprising: a tank body for storing a volume of
associated water, including: a cold water supply line for
delivering associated water to the tank body, and, a water
discharge line for egress of heated associated water from the tank
body; a first type of heater for heating the associated water in
the tank body; and, a second type of heater having a different
energy/fuel source than the first heater type for heating the
associated water.
2. The water heater of claim 1, wherein the first heater type
includes a heat pump.
3. The water heater of claim 2, wherein the heat pump includes: an
evaporator; a compressor operatively associated with the
evaporator; a condenser for transferring heat thereto; a
restriction, and a fan operatively associated with the evaporator
for directing ambient air over the evaporator and transferring heat
thereto.
4. The water heater of claim 3, wherein the condenser is wrapped
around an outer surface of the tank body.
5. The water heater of claim 1, wherein the second heater type is a
gas burner.
6. The water heater of claim 5, wherein the gas burner assembly is
situated at and heats a base portion of the tank body.
7. The water heater of claim 5, wherein the gas burner assembly is
situated proximate to the tank body.
8. The water heater of claim 1, further including: at least one
sensor for measuring a temperature of the associated water stored
in the tank body; and, a controller receiving a signal from the at
least one sensor indicative of associated water temperature; and,
the controller actuates at least one of the first and second
heaters in response to the sensed temperature.
9. The water heater of claim 1 wherein one of the first and second
heater types is operational in the event of an electrical power
outage.
10. A method of heating water, comprising: delivering water to a
tank body through a water supply line; storing a volume of the
water in the tank body; heating the water in the tank body with a
first type of heater; and, selectively using a second type of
heater having a different energy/fuel source than the first heater
type to heat the water when a threshold is met.
11. The method of claim 10, further including using a heat pump
assembly for the first heater type.
12. The method of claim 11, further including using a gas burner
assembly for the second heater type.
13. The method of claim 10, wherein a first heater type heats the
water to a preselect temperature, and a second heater type
supplements heating of the water.
14. The method of claim 10, wherein the first heater type is a heat
pump and the second heater type is a gas burner assembly.
15. A water heater, comprising: a tank body for storing a volume of
associated water, including: a cold water supply line for
delivering associated water to the tank body, and, a water
discharge line for egress of heated associated water from the tank
body; a heat pump for heating the associated water in the tank body
with an associated working fluid that circulates through the heat
pump, including: an evaporator, a compressor, a condenser for
transferring heat to the associated water stored in the tank body,
a throttling device, and, a fan for directing air over the
evaporator and transferring heat from the air to the associated
working fluid in the evaporator; and, a gas burner assembly for
heating the associated water; at least one sensor for measuring a
temperature of associated water stored in the tank body; and, a
controller receiving a signal indicative of the temperature of the
associated water and selectively using the heat pump and/or gas
burner.
16. The water heater of claim 15, wherein the controller actuates
the gas burner assembly if a relative temperature change over a
preselect time period exceeds a threshold value.
17. The water heater of claim 15, wherein the condenser is received
around an outer surface of the tank body.
18. The water heater of claim 15, wherein the gas burner assembly
is situated at and heats a base portion of the tank body.
19. The water heater of claim 15, wherein the gas burner assembly
is situated proximate to a surface of the tank body.
20. The water heater of claim 15 further comprising a demand
response module for communicating with an associated utility, and a
controller that receives data input from the water heater and the
utility to determine a desired operation of the water heater.
21. The water heater of claim 15 wherein the condenser is either
located remotely and water from the tank body is recirculated via a
pump or via natural convection to the condenser and back to the
tank body, or the condenser is in direct contact with water in the
tank body.
Description
BACKGROUND OF THE DISCLOSURE
[0001] This disclosure is directed to water heaters, and is more
particularly directed to a hybrid water heater that is also
referred to as a dual fuel water heater or hybrid heat pump gas
water heater.
[0002] One skilled in the art understands that different heat
sources offer different advantages, and likewise have different
disadvantages. For example, full-sized tank water heaters usually
require either an electrical connection in which the circuit is a
220/240 V and 30 amp circuit or a gas connection capable of
supplying 40 to 100 K BTUs per hour. Typically, the tank water
heater relies upon a single energy source--either electric or gas.
Thus, installations in the home are made based upon the energy
requirements of the water heater. That is, either a 30 amp
connection or a gas connection is provided in order to connect with
an electric or gas water heater, respectively, in the home.
[0003] As will be appreciated, replacement water heater units for
the home are usually based upon the previous type of installation.
For example, if the homeowner wants to replace a gas water heater,
then a similar sized gas water heater is purchased to "drop-in" as
a replacement. Preferably, the gas and flue connections are
substantially identical, the electrical connection for the gas
water heater is similar, and the inlet and outlet water connections
are likewise similar to facilitate ease of replacement.
[0004] On the other hand, rather than merely replacing an electric
water heater with a new electric water heater, some consumers have
opted to switch to a hybrid water heater that uses a highly
efficient heat pump water heater available as a "drop-in"
replacement for the electric water heater market. Typically, the
heat pump water heater is operated at 240 V and 30 amps so that the
replacement hybrid heat pump water heater is direct wired in the
same fashion as a standard electric water heater. Likewise, the
same water inlet and outlet configurations are used in the new heat
pump water heater to facilitate replacement. One commercially
available hybrid-type water heater includes multiple resistor type
heaters and a heat pump type heat source used to heat the water in
the tank. A controller energizes one or more of these heat sources
in response to various temperature data inputs. The water
temperature and the rate of temperature change are monitored, and
the data input to a controller which then determines which heat
source to use, i.e., the compressor of the heat pump, the upper
electric resistance heater, and/or the lower resistance heater.
[0005] Heat pumps are highly efficient but take a longer period of
time to raise the temperature of the water in the tank. Gas
burners, on the other hand, can quickly raise the temperature of
the water in the tank. Nevertheless, no hybrid, heat pump water
heater offering is available as a replacement in the gas water
heater market. Gas fuel costs versus electrical costs in some areas
make the electrical heat pump water heaters less attractive in
terms of payback. Further, higher installation costs are required
if a heat pump water heater is installed as a replacement and
particularly if the replacement water heater requires a 240 volt,
30 amp dedicated circuit. That is, tank gas water heaters do not
require the elevated voltage or amperage in a dedicated circuit and
therefore a homeowner would have to update the electrical service
if a hybrid heat pump electrical water heater were used to replace
the gas water heater. Likewise, utilities may resist fuel switching
from gas to electric. Hence, a 240 V heat pump water heater may not
be as attractive to a consumer/homeowner or may encounter other
resistance as a replacement to a gas water heater.
[0006] Another obstacle to replacing a gas water heater, and
particularly one that is at least partially electric such as a gas
heat pump water heater, is that installation costs are a big
factor. Electrical connections, gas line connections, and the
associated flue all contribute to the potential cost to the
homeowner who is considering a change to a gas heat pump water
heater as a substitute for the gas water heater.
[0007] Utilities also become a factor. There are times when a
utility wants to encourage electrical use, and still other times
such as peak demand when the utility would prefer that the consumer
not use electricity for the water heater. Therefore, if a homeowner
is considering moving away from a gas water heater to electric
water heater, for example one that uses 240 V, a utility may offer
some resistance to such change.
[0008] Thus, a need exists for a high-efficiency, hybrid heat pump
water heater, and more specifically a gas heat pump water heater or
dual fuel water heater, replacement to a gas water heater where the
heat pump portion of the hybrid water heater can maintain the hot
water temperature at a lower cost than using a high-powered gas
burner when water is not being used or when the draw is low.
Further, the high-efficiency hybrid heat pump water heater is
capable of using the voltage and current level that is readily
available in a convenient outlet located near a gas water heater
installation that is being replaced. Likewise, the replacement must
be as compatible with existing connections as possible to minimize
any cost to the homeowner related to the changeover, i.e., gas
connections, electrical connections, flue connections, footprint,
etc.
SUMMARY OF THE DISCLOSURE
[0009] A first exemplary embodiment of the disclosure is directed
toward a water heater including a tank body for storing a volume of
water. A cold water supply line delivers water to the tank body. A
water discharge line provides for egress of heated water from the
tank body. The water heater further includes a first type of heater
and a second type of heater using a different energy/fuel source
than the first heater type for heating the water in the tank
body.
[0010] The disclosure is directed toward a water heater including a
tank body for storing a volume of water. The water heater includes
a cold water supply line for delivering water to the tank body and
a water discharge line for egress of heated water from the tank
body. The water heater further includes a heat pump for heating the
water in the tank body. The gas burner is mounted within or
adjacent but external to the tank body to transfer heat to the
water stored in the tank body, or the gas burner may be an
instantaneous type water heater that raises the temperature of the
outlet water.
[0011] An exemplary water heating method of the present disclosure
includes delivering water to a tank body through a water supply
line and storing a volume of the water in the tank body. The method
further includes heating the water in the tank body with a first
type of heater, and selectively using a second type of heater using
a different energy/fuel source than the first heater type to heat
the water in the tank body when a threshold is met.
[0012] One advantage of the present disclosure is to provide a
hybrid water heater that operates with high energy efficiency.
[0013] Another advantage of the present disclosure is to provide a
water heater that reduces costs of operating and installation.
[0014] Still another advantage of the present disclosure relates to
providing a high efficiency electric heat pump to maintain hot
water temperature at a lower cost than using a high-powered gas
burner when water is not being used or when hot water consumption
is low or moderate.
[0015] Yet another advantage is that with a hybrid gas heat pump
water heater if electrical power is lost, hot water can still be
provided to the homeowner.
[0016] The present disclosure provides the consumer a choice of a
gas or electric water heater for new construction, as well as
replacing a gas water heater with a hybrid gas heat pump water
heater.
[0017] A dual fuel heat pump water heater/gas water heater that can
easily drop-in and replace a standard gas water heater that
preferably has the same inlet and outlet water connections, the
same gas vent pipe connection, same relative footprint, and that
will operate in the event of loss of electrical power.
[0018] Still other benefits and advantages of the present
disclosure will become apparent upon reading and understanding the
following detailed description
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 (FIGS. 1A and 1b) shows a hybrid heat pump gas water
heater assembly.
[0020] FIG. 2 (FIGS. 2A and 2B) is another embodiment of the dual
fuel, hybrid heat pump gas water heater assembly.
[0021] FIG. 3 (FIGS. 3A and 3B) is still another embodiment of the
dual fuel, hybrid heat pump gas water heater assembly.
[0022] FIG. 4 is a flow-chart for an exemplary mode of
operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIG. 1 illustrates a multiple heater type water heater
(hereinafter "hybrid water heater 10) according to an exemplary
embodiment of the disclosure. The hybrid water heater 10 includes a
first heater type 12 and a second heater type 14, which is a
different fuel or energy source from the first heater type. More
specifically, the first heater type 12 is a heat pump system and
the second heater type 14 is a gas burner assembly. It is
contemplated that the presently disclosed hybrid water heater 10
can be installed as an alternative water heater in regions of the
country that traditionally use a gas water heater, or can be used
as a replacement for a gas water heater. When used as a
replacement, consideration is also given to ease of replacement and
includes drop-in features such as aligning and sizing with an
exhaust gas flue, gas supply, water connections, and size. For
example, the exhaust duct size may be 3 inches for 40,000 BTU
burners or less, and typically 4 inch diameter doctors use for
burners greater than 40,000 BTUs. Existing gas lines are typically
1/2 inch and 3/4 inch, and the electrical connection is preferably
a 120 V corded plug that can reach a 120V, 15 amp outlet.
[0024] The present disclosure is directed toward a stand-alone
storage water heater 10 including a housing 15 that encloses a tank
body 16 for storing a volume of water therein. Cold water is
delivered to the tank body 16 from a water supply line 18 (i.e., a
"dip tube") connected to a cold water supply (not shown). This
water supply line 18 delivers the cold water toward a bottom
portion of the tank body 16, and the delivery of the cold water
displaces a volume of water already contained therein the lower
region toward a top portion of the tank body. Because warm water is
less dense than cold water, the warmer water rises to the top
portion of the tank body 16. Therefore, a water outlet or egress
line 20 is situated at the top portion of the tank body 16 for
delivery of heated water to various faucets and appliances in the
home.
[0025] The heat pump 12 is mounted to the tank body 16. One
exemplary heat pump is described in application Ser. No. ______
(Attorney Docket No. 60280.0012US01; GE Docket No. 225439) to
Nelson, et. al.; however, operation and features of the heat pump
are not limited to any one disclosure. Any known heat pump system
may be incorporated into the present water heater 10 to achieve a
function of the disclosure including activation of the heat pump
heater type corresponding to at least one mode of operation. In the
illustrated embodiment, the heat pump 12 includes a compressor 24,
condenser 28, a restriction, an evaporator 22, and a fan 26. A
working fluid circulates through the heat pump to heat the water in
the tank body 16. More specifically, the fan 26 directs the warm
ambient air over the evaporator 22 for transferring heat into the
working fluid. The working fluid (e.g., a refrigerant) exits the
evaporator 22 in vapor gas form, i.e., in a near gas state. The
working fluid is received in the compressor 24, where it increases
in pressure and temperature to an associated superheated gas vapor
as it enters the condenser. The vapor enters the condenser 28 and
transfers energy to the water stored in the tank body 16. The
working fluid vapor changes phase to liquid state as the energy is
transferred to the water. A throttling device (not shown) receives
the working fluid before it returns to the evaporator.
[0026] In the illustrated embodiment, the evaporator 22, the
compressor 24, and the fan 26 are mounted to a top, horizontally
extending and planar surface of the housing 15, however, there is
no limitation made herein to a surface of the housing body of which
the various components of the heat pump 12 are supported. In one
embodiment, the condenser 28 is in contact with a (e.g.,
continuous) sidewall surface 30 of the tank body 16 for
transferring heat to the water contained therein. In the preferred
embodiment, the condenser 28 is in contact with the sidewall 30 of
greatest surface area, e.g., the elongated sidewall of the tank
body. In the illustrated embodiment, the condenser 28 is preferably
wrapped around an exterior sidewall surface of the tank body 16 in
a helical or serpentine fashion, or in any other manner that
provides for effective heat transfer with the tank body. In this
embodiment, an insulator or similar functioning insulating material
29 may surround the outer sidewall surface of the tank body 30
within the housing 15, thus limiting heat loss to the ambient air.
In this manner, the condenser 28 is situated between the outer
sidewall surface 30 of the tank body 16 and the insulator 29. In
another contemplated embodiment, the condenser 28 can be situated
in the interior 32 of the tank body 16 where it is in direct
contact with the water. Embodiments are further contemplated in
which a heat exchanger (not shown) is situated external to the
housing 15, wherein water is pumped from the tank body at a first
temperature, through the heat exchanger where energy is transferred
thereto, and returned to the tank body at a higher temperature.
[0027] The second heater type 14 is a gas burner assembly that
includes a standing or an intermittent pilot, which ignites a gas
flame in a main burner of the assembly. In the illustrated
embodiment of FIG. 1, the gas burner assembly 14 is shown situated
at and heating a base portion of the tank body 16. The gas burner
assembly heats the colder water contained at the bottom of the tank
body 16 due to its greater density.
[0028] A majority of the gas water heaters have a 3 inch vent pipe
that comes out the top of the appliance, although some have a 4
inch vent pipe. Preferably the drop-in heat pump water heater/gas
water heater will replace a 3 inch vent pipe, although some models
could also be available for replacing the 4 inch vent pipe. The
replacement model for the 3 inch vent pipe will only have a 40,000
BTU maximum burner, whereas a 4 inch vent pipe can accommodate a
larger BTU burner. It will also be appreciated that a dual fuel
water heater with a 3 inch flue/vent pipe can be installed in a 4
inch vent pipe application. Typically, a 1/2 inch gas supply line
is provided for existing gas water heaters, and thus the dual fuel
heat pump water heater of the present disclosure is intended to
serve as a drop-in unit without having to change any of the
existing infrastructure.
[0029] In the first configuration of FIGS. 1A and 1B, there is
shown a 120 V heat pump water heater with storage tank and a
standard burner. The dual fuel heat pump water heater has the
ability to operate with the loss of electrical power, it has the
ability to drop in and hook up to a 3 inch vent pipe, and uses the
same gas supply, that is a 1/2 inch or 3/4 inch gas supply line, as
the standard gas water heater that it replaces. This dual fuel
hybrid heat pump gas water heater does require external power
whereas an existing gas water heater does not, but the dual fuel
hybrid heat pump water heater of the present application is
designed to connect with the 120 V circuit (e.g. a cord connection
able to plug-in to a nearby, convenient electrical outlet versus
installation of a dedicated 240V, 30 A circuit).
[0030] The illustrated embodiment of FIG. 1 shows a flue 34
extending vertically upwardly coincident or in proximity to a
central axis of the housing 15 or tank body 16. This flue 34 vents
byproducts of combustion. The flue gases naturally rise through the
flue 34, which extends toward or connects with further ductwork
(not shown) terminating at an exterior of the home. Of course one
skilled in the art will appreciate that the present disclosure is
not limited to a natural draft ventilation system and that a
direct-vent, a horizontally extending vent, or a fan-assisted or
power-vented ventilation system can be used without departing from
the scope and intent of the present disclosure.
[0031] Other embodiments are contemplated in which the gas burner
assembly is situated proximate to an outer surface of the tank body
16 and spaced from a base portion of the tank body 16. One example
shown in FIG. 2 (FIGS. 2A and 2B) includes a removed gas burner
assembly 14 situated adjacent and exterior to the sidewall 30 of
the housing 15. In this embodiment, it is envisioned that the water
can be introduced from the tank body 16 through a conduit 17 that
passes in proximity to the ignited gas burner assembly 14 in order
to heat the water. The water returns to the tank body at a
temperature higher than the temperature it was before the gas
heater cycle. Since the gas burner assembly 14 is situated at a
location removed from directly beneath the bottom surface of the
tank body 16, a flue extends upwardly from the gas burner assembly
14 to carry away combustion gases produced therefrom. There are
several advantages associated with this arrangement: (1) the flue
34 does not consume space inside the tank body 16, and hence the
tank is capable of containing a greater volume of water; (2) the
flue does not extend outwardly and upwardly from a top surface of
the tank body, and therefore does not obstruct various arrangements
for the heat pump components mounted on the top surface of the
water heater; and, (3) the flue does not remove energy from the
standing water stored in the tank body, and therefore does not
contribute to lowering the temperature of the water surrounding the
flue. It does have the disadvantage of an increased footprint for
the water heater (which may not be an issue for new construction),
and possibly impacting ease of replacement of a smaller standard
gas water heater.
[0032] The heat pump water heater with a gas burner on the side and
not on the bottom as shown in FIG. 2 is provided with a 120 V heat
pump water heater, and a storage tank with a side arm style burner
that still uses the same return flow style condenser. The burner
heats water in the tank through a side arm heat exchanger (i.e. it
is not intended as an outlet flow instantaneous type water heater
design) and thus is intended to raise the tank temperature to a
desired temperature level. Generally the burner is much higher
capacity than a standard natural draft style burner (e.g. 40,000
BTU burner) and therefore the same venting cannot be used, and may
have to use an increased gas supply (e.g. changing from a 1/2 inch
gas supply to a 3/4 gas supply line), although it is preferred that
the gas supply line need not be changed and instead the largest
burner available without increasing the gas supply line would be
desired.
[0033] For example, gas line and vent pipe size limitations may
govern the "drop-in" envelope requirements of the dual fuel heat
pump water heater. It is generally known that a standard gas water
heater that is drop-in ready has a naturally vented installation, a
1/2 inch gas line, and a 3 or 4 inch vent or vent connector. By
definition, a vent exits vertically through the roof of a home or
similar structure, and exhausts combustion products of the
naturally-drafted water heater and any other naturally-drafted
appliances. A vent connector attaches from the draft hood of an
appliance to the main vent that exits the home. Likewise,
appliances may also be attached directly to the vent without a vent
connector. Vent materials may include single or double wall metal
pipe, a lined masonry chimney, or other code or agency-approved
vent material. For a 3 inch existing vent or vent connector, a
drop-in gas water heater must have a burner rated at 40,000 BTU per
hour or below. For a 4 inch existing vent or vent connector, the
burner rating is limited to 134,000 BTU per hour (for a 50 foot
vent height). Two or more naturally vented appliances with a 4 inch
vent and connectors are limited to 89,000 BTUs per hour for a 100
foot vent height, 86,000 BTUs per hour for a 50 foot vent height as
provided by the NFPA National Fuel Gas Code vent sizing regulation.
The capability of a 1/2 inch gas line is dependent on the number of
other gas appliances in the home, the length of the gas line
between the home meter and the appliance, and the pressure in the
gas line. Each consumer or homeowner has a potentially different
installation. The maximum 1/2 inch pipe capacity with a straight
length of 10 feet will allow for an appliance rated up to 175,000
BTUs per hour (NFPA National Fuel Gas Code vent sizing for pressure
less than 2 psi in W.C. Drop). Tankless-style and power-vented gas
water heaters can also be included, with metal or PVC vents, 2-4
inches in diameter, up to a maximum capacity of a 1/2 inch gas line
as defined above. The drop-in duel fuel heat pump water heater must
be able, therefore, to attach to a 3-4 inch vent with a maximum
burner rating for the 3 inch vent of 40,000 BTUs, a 4 inch vent has
a maximum 134,000 BTUs, a 1/2 inch gas line, and preferably the
dual fuel heat pump water heater is able to plug into a standard
120 V outlet so that no dedicated circuit for the water heater is
required.
[0034] It would also be desirable to not have to change the vent
pipe, however, this will be required in some arrangements because
code will require a forced draft associated with a tankless burner
that requires a fan and cannot be ducted into the same chimney
associated with a natural venting style burner. Therefore, some
configurations will require venting to an independent chimney or a
wall vent per code requirements.
[0035] In still another embodiment of FIG. 3 (FIGS. 3A and 3B), the
water can be routed from the gas burner assembly 14 situated at the
outlet (i.e., outside of the tank body 16 and may be within the
housing) and directly to an appliance or delivery faucet. In the
configuration of FIG. 3, the burner 14 is provided on the outlet
and is not intended to heat the water in the entire tank. The heat
pump is used to heat the water in the tank, and the burner raises
the temperature of the water passing through the outlet to the
final desired temperature if the tank temperature is not sufficient
to meet the temperature demand. A 120 V heat pump water heater with
the storage tank is provided that uses a high efficiency burner.
The burner of FIG. 3 heats the outlet water, and raises the outlet
temperature to a desired level whenever the heat pump is unable to
deliver water at the desired temperature level. The burner capacity
of this configuration is limited by the existing gas supply, and in
this arrangement, there is requirement to vent to the independent
chimney or the wall vent per code requirements. Therefore, this
configuration of FIG. 3 (like the embodiment of FIG. 2) has some
advantages in replacing a conventional gas water heater, but may
not be as desirable as the embodiment of FIG. 1 which more
completely matches all of the associated infrastructure.
[0036] A controller 36 is operatively associated with both the
first and the second heater types 12 (heat pump), 14 (gas burner).
The controller 36 selectively energizes the heater types based on
data representative of water temperature within the interior tank
body and/or the occurrence of a flow event transmitted to the
controller 36 for processing. The controller 36 is operatively
connected to the first and second heater types 12, 14 and includes
a module that facilitates the automatic selection and energizing of
at least one of the heat pump 12 and the gas assembly 14 in
response to the data received that is representative of the water
temperature and/or flow event.
[0037] At least one sensor 38 measures the temperature of the water
stored in the tank body. The controller 36 receives a signal from
the sensor(s) 38 indicative of the water temperature. The
controller 36 can use inputs from other sensors to base
calculations and to make similar determinations. The sensor 38, for
example, may be situated in or on the tank body 16 to measure water
temperature. A first sensor may be placed on or in a lower portion
of the tank body 16 to monitor water temperature in that region.
Alternatively, the sensor may be placed in an upper portion of the
tank body 16 depending on the particular embodiment of dual fuel,
hybrid gas water heater that is used. In still another arrangement,
at least first and second sensors may be placed on or in at least
two regions of the tank body 16.
[0038] In other arrangements, additional data or sensor information
may be provided to the controller. For example, a sensor such as a
thermistor may be added to monitor one or more of the compressor
outlet, the evaporator inlet, evaporator outlet, or sense ambient
temperature. However, one skilled in the art will appreciate that
these additional sensors are optional only and may provide greater
accuracy or control, although the additional sensors are not
required for effective operation of the dual fuel/hybrid heat pump
gas water heater.
[0039] For example, with respect to the embodiment of FIG. 1, the
controller receives sensor inputs T1 and T2, i.e. representative of
two sensors on the tank, although it may be possible to use a
single sensor to monitor the tank temperature. If two sensors are
used, one of the sensors may be used for the redundant gas control
(if power is lost) and the water heater would be capable of
operating without power using the single sensor. However, if
external power is provided, the main control monitors the first or
upper sensor and operates the water heater based on this data. In
yet another embodiment, two sensors can be used by the same
controller, with the output from the first sensor being used to
operate the first heater type, and the output from the second
sensor being used to operate the second heater type.
[0040] The controller may receive data regarding the evaporator
inlet (T3A) and the evaporator outlet (T3B), the compressor
discharge temperature (T4), and ambient temperature (T5). The main
control can turn the heat pump on and off as an output, and
likewise turn the gas burner on and off as an output. In addition,
the controller may provide an output signal to an external boost
fan for ducted kits.
[0041] Still further, the main controller may provide for mode
selection and the controller preprogrammed for various modes. For
example, in an "economic mode", heat may only be provided by the
heat pump which in the long run is the most energy efficient.
Another choice may be to use a "hybrid" mode in which control could
be alternated between the heat pump and the gas. Still another
choice is to use a "standard gas" mode, that is, to operate the
dual fuel heater in a gas only mode. Still another choice may be a
"high demand" mode which uses the heat pump and gas as a mix, but
more readily uses gas. By way of example only, in the "hybrid" mode
noted above, gas is used as a backup when the tank is substantially
emptied but in the "high demand" mode, gas is used readily when the
tank is only partially emptied. Still another mode could be
"external demand response module" in which operation of the dual
fuel water heater depends on a utility provided real-time signal or
data that would operate the water heater as the utility would
prefer. In still another mode, referred to here as a "low dollar
cost mode", the user inputs the gas and electricity rates and the
controller then operates the dual fuel water heater in the lowest
cost or expense to the homeowner. Yet another option may be a "peak
load control" mode that serves as a balance between the homeowners
desired use of the dual fuel water heater based on cost or expense
relative to the real-time electric and gas rate data received from
the utility. Accordingly, the user interface of the controller
would allow a homeowner to select one of these options or modes,
although one skilled in the art will understand that these modes
are representative only and other modes could be used or provided
as options without departing from the scope and intent of the
present disclosure.
[0042] One feature associated with the present disclosure is an
ability to utilize the least expensive utility in regions of the
country that generally heat water by only a gas water heater
source. It is anticipated that the heat pump 12 portion of the
presently disclosed water heater 10 can operate on a maximum of six
amps and one-hundred-twenty volts power, which is a voltage and a
current level readily available at most convenience outlets located
in proximity of the water tank installation. Electric utility can
be used for the main heater type source to generally heat the water
for slower recovery periods, but the gas utility can be used for
instances requiring faster recovery periods. The threshold value
can be programmed into the controller 36 to be such that the
controller deactivates the first heater type 12 and actuates the
second heater type 14 at values that are the most economical and
cost efficient. The controller may selectively set, reset and/or
change predetermined temperature thresholds based on input received
from an energy billing device, which indicates periods of high and
low energy demand. Alternatively, the temperature thresholds can be
input by a homeowner at a user interface, or the user inputs
current average gas rates and electrical rates, and the controller
uses the lowest total cost source of the mix/ratio/combination to
heat water at the lowest cost. Other embodiments are contemplated
which utilize a twenty Amp, two-hundred-forty volt circuit. Still,
there is no limitation made herein to a capacity or a power range
in which the heat pump heater type requires or utilizes.
[0043] FIG. 4 illustrates a method of heating water in a water tank
utilizing the two heater types disclosed herein and, more
specifically, a method of heating the water stored in the tank
utilizing at least two modes of operation. The controller receives
inputs at any given time and operatively manages various modes of
operation to achieve set temperatures as shown in FIG. 4. The
method starts at step 200. The tank body is filled with water from
an external water supply source through the water supply line at
step 202. This water is generally cold and/or cooler in temperature
than the water stored in the tank depending on the season and the
source of supply. The controller receives a signal 204 from a water
tank sensor indicative of the temperature of the water. The
temperature is compared against a threshold temperature value 206.
The controller actuates the first heater type 208 if the water
temperature is below the temperature threshold value. The
controller more specifically actuates the first heater type 208 by
controlling the power supply to the heat pump fan(s) and power to
the compressor.
[0044] Another instance when water may fall below the temperature
threshold value is when the water volume is left in the tank for
long durations. For example, if there is no water displacement
occurring as a result of water removed from the tank for delivery
to faucets and appliances, then the tank water may fall below the
desired temperature threshold value. In both instances, the
controller can actuate the first heater type 208 to heat the water
to the desired temperature. For example, the controller actuates
the first heater type 208 to heat the water to a temperature having
a preselected threshold value. In another embodiment, the
controller 36 may also set and adjust threshold temperature values
based on predicted demands, which the controller estimates using
previous water usage patterns that it tracks. The user interface
(not shown) may also be included on an exterior of the water tank
10 for user-input, wherein user-selected temperature threshold
settings may be programmed into the controller for the
predetermined values used in the controller calculations.
[0045] The first heater type preferably maintains the value above
the set-point 210. In one embodiment, the controller de-energizes
212 the first heater type once the temperature of the water reaches
above the set-point temperature. The first heater type then
re-energizes 212 when the temperature falls below the set
point.
[0046] Dual fuel water heaters are also dependent on the relative
costs of the different fuels. At times, electricity may be a more
stable cost and thereby a utility may encourage the homeowner to
use the heat pump and only occasionally use the backup or gas
burner during those periods of peak need. Thus, interaction or
communication with utility is often required so that the homeowner
is encouraged to flexibly use the dual fuel water heater and take
advantage of benefits offered by the utility, for example in terms
of cost. If the homeowner has only a single fuel water heater, the
choice in response to communication from the utility would be a
simple on/off condition, i.e., either use the water heater or don't
use the water heater dependent on the communication received from
the utility. However, with the dual fuel water heater, the choices
for the homeowner are much wider ranging. Therefore, the homeowner
may select one fuel or another based simply on cost, while the
utility may encourage one fuel or another based on what is best for
the overall grid or utility system. It will be appreciated that the
homeowner choice, and that being encouraged by the utility company,
may not always be the same. However, if the water heater is capable
of catering to either the selection of the homeowner or the
suggestion proffered by the utility, then the options or solutions
can likely be satisfied with a dual fuel water heater. Generally,
however, the homeowner will be encouraged to use the heat pump to
slowly and more efficiently heat the water stored in the tank.
Further, and as noted above, the dual fuel water heater offers the
advantage of providing heated water even when electrical power is
lost. Likewise, providing a drop-in replacement that is highly
efficient is also achieved.
[0047] The disclosure has been described with reference to the
preferred embodiments. Obviously, modifications and alterations
will occur to others upon reading and understanding the preceding
detailed description. It is intended that the disclosure be
construed as including all such modifications and alterations.
* * * * *