U.S. patent application number 12/287841 was filed with the patent office on 2010-04-15 for hybrid heating system and method.
Invention is credited to Reza Naghshineh.
Application Number | 20100090017 12/287841 |
Document ID | / |
Family ID | 42097998 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100090017 |
Kind Code |
A1 |
Naghshineh; Reza |
April 15, 2010 |
Hybrid heating system and method
Abstract
A hybrid heating system (10) and method in which an indoor coil
(12) of a heat pump (14) is located upstream of a heat output of a
non-electric second heat source (22), e.g., a gas or liquefied
petroleum gas furnace. The heat pump (14) continues to operate even
at low temperatures, i.e., below 0.degree. F., and the non-electric
second heat source (22) supplements the heat output of the heat
pump (12) as needed to maintain a desired indoor temperature,
thereby maximizing economic benefit from the heat pump (12).
Inventors: |
Naghshineh; Reza; (Kansas
City, MO) |
Correspondence
Address: |
Gerhard Shipley
300 Clayton Court
Lawrence
KS
66044
US
|
Family ID: |
42097998 |
Appl. No.: |
12/287841 |
Filed: |
October 11, 2008 |
Current U.S.
Class: |
237/2B |
Current CPC
Class: |
F24H 9/2071 20130101;
F24D 2200/04 20130101; F24D 2200/12 20130101; F24H 9/2085 20130101;
F24H 3/12 20130101 |
Class at
Publication: |
237/2.B |
International
Class: |
F24D 15/04 20060101
F24D015/04 |
Claims
1. A heating system comprising: a heat pump having an indoor coil
and operable to generate a first heat output; and a non-electric
second heat source configured to introduce a second heat output
downstream of the indoor coil, wherein the heat pump and the second
heat source operate substantially simultaneously when a demand for
heat exceeds the first heat output of the heat pump.
2. The heating system as set forth in claim 1, wherein the heat
pump is a high-efficiency heat pump having a coefficient of
performance of 3 or better.
3. The heating system as set forth in claim 1, wherein the
non-electric second heat source is a natural gas furnace.
4. The heating system as set forth in claim 1, wherein the
non-electric second heat source is a liquefied petroleum gas
furnace
5. The heating system as set forth in claim 1, wherein the
non-electric second heat source is a high-efficiency variable
capacity non-electric furnace operable to provide different amounts
of heat so as to more closely supplement the first heat output of
the heat pump.
6. The heating system as set forth in claim 1, further including a
first temperature sensor located downstream of the indoor coil and
operable to monitor the first heat output, and to control operation
of the heat pump.
7. The heating system as set forth in claim 1, further including a
blower located downstream of the indoor coil.
8. The heating system as set forth in claim 1, further including a
second temperature sensor located downstream of a heat exchanger
component of the non-electric second heat source.
9. A heating system for heating an enclosed space to a desired
temperature, the heating system comprising: a housing having an
intake opening and having an exhaust opening located downstream of
the intake opening; a heat pump operable to generate a first heat
output, the heat pump having an indoor coil located substantially
within the housing; a blower located within the housing and
operable to push air in the downstream direction; and a
non-electric second heat source configured to provide a second heat
output within the housing downstream of the indoor coil, wherein
the heat pump and the second heat source operate substantially
simultaneously when a demand for heat exceeds the first heat output
of the heat pump.
10. The heating system as set forth in claim 9, wherein the heat
pump is a high-efficiency heat pump having a coefficient of
performance of 3 or better.
11. The heating system as set forth in claim 9, wherein the
non-electric second heat source is a natural gas furnace.
12. The heating system as set forth in claim 9, wherein the
non-electric second heat source is a liquefied petroleum gas
furnace.
13. The heating system as set forth in claim 9, wherein the
non-electric second heat source is a high-efficiency variable
capacity non-electric furnace operable to provide different amounts
of heat so as to more closely supplement the first heat output of
the heat pump.
14. The heating system as set forth in claim 9, further comprising
a first temperature sensor located downstream of the indoor coil
and operable to monitor the first heat output, and to control
operation of the heat pump.
15. The heating system as set forth in claim 9, further comprising
a second temperature sensor located downstream of a heat exchanger
component of the non-electric second heat source.
16. A heating system for reaching and maintaining a desired
temperature of an enclosed space, the heating system comprising: a
housing having an intake opening and having an exhaust opening
located downstream of the intake opening; a heat pump operable to
generate a first heat output, the heat pump having an indoor coil
located substantially within the housing; a first temperature
sensor located downstream of the indoor coil and operable to
monitor the first heat output, and to control operation of the heat
pump with regard to reaching and maintaining the desired
temperature; a blower located within the housing and operable to
push air in the downstream direction; a non-electric second heat
source configured to introduce a variable second heat output within
the housing downstream of the indoor coil, the non-electric second
heat source having a heat exchanger, wherein the heat pump and the
second heat source operate substantially simultaneously when the
first heat output of the heat pump is, by itself, insufficient to
reach and maintain the desired temperature; and a second
temperature sensor located downstream of the heat exchanger of the
non-electric second heat source and operable to monitor the
combined first and second heat outputs, and to control operation of
the non-electric second heat source and the blower with regard to
reaching and maintaining the desired temperature.
17. The heating system as set forth in claim 16, wherein the heat
pump is a high-efficiency heat pump having a coefficient of
performance of 3 or better.
18. The heating system as set forth in claim 16, wherein the
non-electric second heat source is a natural gas furnace.
19. The heating system as set forth in claim 16, wherein the
non-electric second heat source is a natural gas furnace.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to hybrid heating systems and
methods. More specifically, the present invention concerns a hybrid
heating system and method in which an indoor coil of a heat pump is
located upstream of the heat output of a non-electric second heat
source, e.g., a gas or liquefied petroleum gas furnace; the heat
pump continues to operate even at low temperatures, i.e., below
0.degree. F.; and the second heat source supplements the heat
output of the heat pump as needed to maintain a desired indoor
temperature, thereby maximizing economic benefit from the heat
pump.
BACKGROUND OF THE INVENTION
[0002] Heat pumps operate by extracting heat from outdoor air, and
transferring that heat to an enclosed space, such as a home or
business. Heat pumps are generally more economical to operate than
conventional furnaces that burn fossil fuels. However, as the
temperature of the outdoor air decreases, the amount of extracted
heat also decreases until a desired temperature within the enclosed
space can no longer be maintained by operation of the heat pump
alone. For this reason, some hybrid heating systems incorporate
both a heat pump and a gas furnace, in which the heat pump is
turned off at 35.degree. F. and the furnace turned on in order to
maintain the desired indoor temperature. The main reason that the
heat pump is turned off is that its indoor coil is located
downstream of the furnace, such that the heat pump's compressor
would experience a damagingly high compression ratio due to the
furnace-heated air flowing through the indoor coil. As a result,
the economic advantage of the heat pump is completely lost below a
threshold outdoor temperature, e.g., 35.degree. F., at which the
heat pump is turned off.
[0003] Hybrid systems incorporating a heat pump and an electric
furnace are available in which the heat pump's indoor coil is
located upstream of the electric furnace. Unfortunately, it is both
time-consuming and expensive to reconfigure a building from gas to
total electric heat. For example, gas furnaces provide
higher-temperature air, require less airflow, and therefore use
smaller ducts than electric furnaces. Reconfiguring a building from
gas to total electric heat requires replacing the smaller ductwork,
much of which may be very difficult to access, with larger ductwork
to accommodate a larger volume of air. Reconfiguring a house from
gas to electric heat also requires upgrading the electrical service
by adding a large amount of additional electric capacity, e.g., 200
amperes, to the home's electric system.
[0004] Due to these and other problems and disadvantages in the
prior art, a need exists for a hybrid heating system incorporating
a heat pump and a non-electric second heat source, wherein the heat
pump can continue operating even at low outdoor temperatures.
SUMMARY OF THE INVENTION
[0005] The present invention overcomes the above-identified and
other problems and disadvantages by providing a hybrid heating
system and method in which an indoor coil of a heat pump is located
upstream of the heat output of a non-electric second heat source,
e.g., a gas or liquefied petroleum gas furnace; the heat pump
continues to operate even at very low temperatures, i.e., below
0.degree. F.; and the second heat source supplements the heat
output of the heat pump as needed to maintain a desired indoor
temperature, thereby maximizing economic benefit from the heat
pump.
[0006] In one embodiment, the heating system may comprise a heat
pump having an indoor coil and operable to generate a first heat
output; and a non-electric second heat source configured to provide
a second heat output downstream of the indoor coil, wherein the
heat pump and the second heat source operate substantially
simultaneously when a demand for heat exceeds the first heat output
of the heat pump.
[0007] In various implementations, the system may further comprise
any one or more of the following features. The heat pump may be a
high-efficiency two-stage heat pump having a coefficient of
performance of 3. The non-electric second heat source may be a
natural gas or liquefied petroleum (LP) gas furnace. The
non-electric second heat source may be a high-efficiency variable
capacity non-electric furnace operable to provide different amounts
of heat so as to more closely supplement the first heat output of
the heat pump. A first temperature sensor may be located downstream
of the indoor coil and operable to monitor the first heat output
and control operation of the heat pump. A blower may be located
downstream of the indoor coil. A second temperature sensor may be
located downstream of the non-electric second heat source's heat
exchanger and operable to monitor the combined first and second
heat outputs and monitor the temperature rise across the indoor
coil and the heat exchanger of the non-electric second heat
source.
[0008] These and other features of the present invention are
described in greater detail below in the section titled DETAILED
DESCRIPTION OF THE INVENTION.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0009] The present invention is described herein with reference to
the following drawing figures, which are not necessarily to
scale:
[0010] FIG. 1 is a cross-sectional elevation view representation of
an embodiment of the system of the present invention; and
[0011] FIG. 2 is a flowchart setting forth steps of an embodiment
of the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] With reference to the drawing figures, a system and method
is herein described, shown, and otherwise disclosed in accordance
with various embodiments, including a preferred embodiment, of the
present invention.
[0013] Broadly, the present invention concerns a hybrid heating
system 10 and method for reaching and maintaining a desired
temperature in an enclosed space, in which an indoor coil of a heat
pump is located upstream of the heat output of a non-electric
second heat source, e.g., a gas or liquefied petroleum gas furnace;
the heat pump continues to operate even at very low outdoor
temperatures, i.e., below 0.degree. F.; and the second heat source
supplements the heat output of the heat pump as needed to maintain
a desired indoor temperature, thereby maximizing economic benefit
from the heat pump. Because the heat pump operates substantially
continuously, and is only supplemented by the non-electric second
heat source, the system 10 of the present invention is a true
hybrid heating system, unlike prior art systems which operate one
or the other heat source but not both simultaneously.
[0014] More specifically, with reference to FIG. 1, in one
embodiment the system 10 may comprise a housing 11 having an intake
opening A and an exhaust opening B; a first heat exchange coil 12,
or "indoor coil", associated with a heat pump 14; a first
temperature sensor 16 located downstream of the first coil 12; a
blower 18, or "air handler", located downstream of the first sensor
16; primary and secondary heat exchangers 20A,20B associated with
the non-electric second heat source 22 and located downstream of
the blower 18; and a second temperature sensor 24 located
downstream of the primary and secondary heat exchangers 20A,20B.
Ductwork 26 for delivering the heated air may be connected to the
exhaust opening B.
[0015] The heat pump 14 is operable to generate a first heat output
at the indoor coil 12, which may be located substantially within
the housing 11. The first temperature sensor 16 is operable to
monitor the first heat output, and may be operable to control
operation of the heat pump 14 with regard to reaching and
maintaining the desired indoor temperature. The blower 18 is
operable to push air in the downstream direction, and may also be
located within the housing 11. The non-electric second heat source
22 is configured to introduce a second heat output within the
housing 11 downstream of the indoor coil 12. The heat pump 14 and
the second heat source 22 operate substantially simultaneously when
the first heat output of the heat pump 14 is, by itself,
insufficient to reach and maintain the desired indoor temperature.
The second temperature sensor 24 is operable to monitor the
combined first and second heat outputs, and may be operable to
control operation of the second heat source 22 and the blower 18
with regard to reaching and maintaining the desired indoor
temperature. Temperature sensors 16,24 may also be operable to
protect the system 10 from overheating.
[0016] In one implementation, one, some, or all of the components
of the system 10 may be substantially conventional. In one
implementation, the heat pump 14 may be a high-efficiency two-stage
heat pump having a coefficient of performance (COP) of 3 or better.
In one implementation, the non-electric second heat source 22 may
be a high-efficiency variable capacity non-electric furnace
operable to provide different amounts of heat so as to more closely
supplement the first heat output of the heat pump 14. In one
implementation, the non-electric second heat source 22 is a natural
gas or liquefied petroleum gas furnace. In one implementation, one
or more of the components of the system 10 described above as being
located within the housing 11 are located elsewhere, i.e., not
fully or even partially within the housing 11.
[0017] With reference to FIG. 2, the invention may be characterized
as a method comprising some or all of the steps of providing the
heat pump 14 operable to generate the first heat output at the
indoor coil 12, as shown in box 100; measuring the first heat
output, and, as necessary, controlling operation of the heat pump
14 with regard to reaching and maintaining the desired indoor
temperature, as shown in box 102; pushing the air in the downstream
direction, as shown in box 104; introducing the second heat output
of the non-electric second heat source within the housing 11
downstream of the indoor coil 12, as shown in box 106; operating
only the heat pump 14 when the first heat output is, by itself,
insufficient to reach and maintain the desired indoor temperature,
as shown in box 108; operating the heat pump 14 and the
non-electric second heat source 22 substantially simultaneously
when the first heat output of the heat pump 14 is, by itself,
insufficient to reach and maintain the desired indoor temperature,
as shown in box 110; measuring the combined first and second heat
outputs, and, as necessary, controlling operation of the second
heat source 22 and the blower 18 with regard to reaching and
maintaining the desired indoor temperature, as shown in box
112.
[0018] By way of example and not limitation, the system 10 may
function substantially as follows. Air (indicated as AIRFLOW in
FIG. 1) enters the intake opening A and flows over the indoor coil
12 of the heat pump 14, thereby transferring the first heat output
of the heat pump 14. The first temperature sensor 16 monitors the
temperature of the air downstream of the indoor coil 12. If
operation of the heat pump 14 alone is sufficient to reach and
maintain a desired indoor temperature of the space being heated,
then the non-electric second heat source 22 is not engaged, and the
air is blown out the exhaust opening B and into the ductwork 26 by
the blower 18 and delivered to the space being heated. If operation
of the heat pump 14 alone is not sufficient to reach and maintain
the desired indoor temperature of the space being heated, then the
non-electric second heat source 22 is engaged to provide a
supplementary second heat output which, in combination with the
first heat output provided by the heat pump 14, is sufficient to
maintain the desired indoor temperature of the space being heated.
The second temperature sensor 24 monitors the temperature of the
air downstream of the non-electric second heat source 22. Blower
speed control ensures proper and safe operating temperature across
the indoor coil 12 and the heat exchangers 20A,20B. When it is
necessary to defrost the heat pump 14, the system 10 may rely
entirely on the non-electric second heat source 22 for heat, and to
compensate for the cooling effect of the defrost cycle, until the
heat pump 14 can be returned to the heating cycle.
[0019] Although the invention has been disclosed with reference to
various particular embodiments, it is understood that equivalents
may be employed and substitutions made herein without departing
from the scope of the invention as recited in the claims.
[0020] Having thus described the preferred embodiment of the
invention, what is claimed as new and desired to be protected by
Letters Patent includes the following:
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