U.S. patent application number 12/363064 was filed with the patent office on 2010-08-05 for pulse combustion system for a water heater.
Invention is credited to Dennis R. Hughes, Zinovy Plavnik.
Application Number | 20100192874 12/363064 |
Document ID | / |
Family ID | 42371435 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100192874 |
Kind Code |
A1 |
Hughes; Dennis R. ; et
al. |
August 5, 2010 |
PULSE COMBUSTION SYSTEM FOR A WATER HEATER
Abstract
A water heater. The water heater includes a water circuit
adapted to conduct water to be heated, a combustion system operable
to produce products of combustion and operable to provide the
products of combustion to heat water in the water circuit, and a
fuel train assembly configured to provide fuel to the combustion
system. The fuel train assembly includes a gas expansion chamber, a
first gas shut-off valve positioned upstream of the expansion
chamber, and a second gas shut-off valve positioned downstream of
the expansion chamber.
Inventors: |
Hughes; Dennis R.;
(Hartford, WI) ; Plavnik; Zinovy; (Dunwoody,
GA) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
100 E WISCONSIN AVENUE, Suite 3300
MILWAUKEE
WI
53202
US
|
Family ID: |
42371435 |
Appl. No.: |
12/363064 |
Filed: |
January 30, 2009 |
Current U.S.
Class: |
122/17.1 ;
431/1 |
Current CPC
Class: |
F24H 1/206 20130101;
F23C 15/00 20130101 |
Class at
Publication: |
122/17.1 ;
431/1 |
International
Class: |
F24H 1/18 20060101
F24H001/18; F23C 15/00 20060101 F23C015/00 |
Claims
1. A water heater comprising: a water circuit adapted to conduct
water to be heated; a combustion system operable to produce
products of combustion and operable to provide the products of
combustion to heat water in the water circuit; and a fuel train
assembly configured to provide fuel to the combustion system, the
fuel train assembly comprising: a gas expansion chamber; a first
gas shut-off valve positioned upstream of the expansion chamber;
and a second gas shut-off valve positioned downstream of the
expansion chamber.
2. The water heater of claim 1 wherein the combustion system is a
pulse combustion system creating pressure pulses.
3. The water heater of claim 1 wherein the first gas shut-off valve
and second gas shut-off valve substantially simultaneously adjust
between an open position, in which fuel flows through both valves,
and a closed position, in which fuel does not flow through either
valve.
4. The water heater of claim 1, the fuel train assembly further
comprising a gas flapper valve positioned downstream of the gas
expansion chamber and configured to permit substantially one-way
flow of fuel in a downstream direction.
5. The water heater of claim 1, the fuel train assembly further
comprising a first supply line positioned upstream of the gas
expansion chamber and supplying fuel to the gas expansion chamber
and a second supply line supplying fuel from the gas expansion
chamber to the combustion system.
6. The water heater of claim 1, the fuel train assembly further
comprising a regulator positioned upstream of the gas expansion
chamber to control delivery pressure of fuel to the gas expansion
chamber.
7. A fuel delivery system for delivering fuel to a combustion
system of a water heater tank assembly, the fuel delivery system
comprising: a gas expansion chamber; a first supply line supplying
fuel to the gas expansion chamber; a first gas shut-off valve
positioned in the first supply line and upstream of the gas
expansion chamber; a second supply line supplying fuel from the gas
expansion chamber to the combustion system; and a second gas
shut-off valve positioned in the second supply line and downstream
of the gas expansion chamber.
8. The fuel delivery system of claim 7 wherein the combustion
system is a pulse combustion system creating pressure pulses.
9. The fuel delivery system of claim 7, further comprising a gas
flapper valve positioned in the second supply line downstream of
the gas expansion chamber.
10. The fuel delivery system of claim 7 wherein the first gas
shut-off valve and second gas shut-off valve substantially
simultaneously adjust between an open position, in which fuel flows
through both valves, and a closed position, in which fuel does not
flow through either valve.
11. The fuel delivery system of claim 7, further comprising a
regulator positioned in the first supply line upstream of the gas
expansion chamber.
12. A fuel train assembly for providing fuel to a combustion
system, the fuel train assembly comprising: a gas expansion
chamber; a first gas shut-off valve positioned upstream of the gas
expansion chamber to selectively interrupt flow of fuel into the
gas expansion chamber; and a second gas shut-off valve positioned
downstream of the gas expansion chamber to selectively interrupt
flow of fuel into the combustion system.
13. The fuel train assembly of claim 12 wherein the first gas
shut-off valve and second gas shut-off valve substantially
simultaneously adjust between an open position, in which fuel flows
through both valves, and a closed position in which fuel does not
flow through either valve.
14. The fuel train assembly of claim 12, further comprising a gas
flapper valve positioned downstream of the gas expansion chamber
and configured to permit substantially one-way flow of fuel in a
downstream direction.
15. The fuel train assembly of claim 12 wherein the combustion
system is a pulse combustion system creating pressure pulses.
16. The fuel train assembly of claim 12, further comprising a first
supply line supplying fuel to the gas expansion chamber and a
second supply line supplying fuel from the gas expansion chamber to
the combustion system.
17. The fuel train assembly of claim 12, further comprising a
regulator positioned upstream of the gas expansion chamber and
configured to control delivery pressure of fuel to the gas
expansion chamber.
Description
BACKGROUND
[0001] The present invention relates to water heaters, and more
particularly to pulse combustion systems for gas fired water
heaters.
SUMMARY
[0002] In one embodiment, the invention provides a water heater.
The water heater includes a water circuit adapted to conduct water
to be heated, a combustion system operable to produce products of
combustion and operable to provide the products of combustion to
heat water in the water circuit, and a fuel train assembly
configured to provide fuel to the combustion system. The fuel train
assembly includes a gas expansion chamber, a first gas shut-off
valve positioned upstream of the expansion chamber, and a second
gas shut-off valve positioned downstream of the expansion
chamber.
[0003] In another embodiment, the invention provides a fuel
delivery system for delivering fuel to a combustion system of a
water heater tank assembly. The fuel delivery system includes a gas
expansion chamber, a first supply line supplying fuel to the gas
expansion chamber, a first gas shut-off valve positioned in the
first supply line and upstream of the gas expansion chamber, a
second supply line supplying fuel from the gas expansion chamber to
the combustion system, and a second gas shut-off valve positioned
in the second supply line and downstream of the gas expansion
chamber.
[0004] In another embodiment, the invention provides a fuel train
assembly for providing fuel to a combustion system. The fuel train
assembly includes a gas expansion chamber, a first gas shut-off
valve positioned upstream of the gas expansion chamber to
selectively interrupt flow of fuel into the gas expansion chamber,
and a second gas shut-off valve positioned downstream of the gas
expansion chamber to selectively interrupt flow of fuel into the
combustion system.
[0005] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 illustrates a water heater system according to the
invention.
[0007] FIG. 2 is an exploded view of a tank extension and
combustion system of the water heater system.
[0008] FIG. 3 is a perspective view of the tank extension and
combustion system of the water heater.
[0009] FIG. 4 is a schematic of the fuel train assembly for use
with the system of FIG. 1.
[0010] FIG. 5 is an end view of an inlet air tube coupled to a
combustion chamber of the water heater system.
[0011] FIG. 6 is another embodiment of an air inlet tube of the
present invention.
[0012] FIG. 7 is a perspective view of one embodiment of a gas
flapper valve for use in the fuel train of FIG. 4.
DETAILED DESCRIPTION
[0013] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless specified or limited otherwise,
the terms "mounted," "connected," "supported," and "coupled" and
variations thereof are used broadly and encompass both direct and
indirect mountings, connections, supports, and couplings. Further,
"connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.
[0014] The present invention is intended for use with a gas fired
water heater. Furthermore, the water heater system and fuel train
assembly are described for use with a pulse combustion system that
creates pressure pulses. However, the water heater system and fuel
train assembly may be utilized with other types of combustion
technologies.
[0015] FIG. 1 illustrates a water heater system 10 embodying the
present invention. The water heater system 10 includes an inlet air
vent 14, an inlet air decoupler 18, inlet air piping 22, a blower
26, an air chamber 30, a tank extension 34, a combustion system 36
(FIG. 2), and a generally cylindrical tank 38. The water heater
system 10 further includes an exhaust decoupler 42, exhaust piping
46 and a muffler 50. The water heater system 10 further includes a
fuel train assembly 54 (illustrated schematically in FIGS. 2, 3,
and 4) configured to provide fuel to the combustion system 36
through a fuel nozzle 62 (illustrated schematically in FIGS. 3 and
4).
[0016] In general, the pulse combustion system 36 works through
ignition of an air/fuel mixture in a combustion chamber 58 of the
combustion system 36 to create cyclical pressure pulses in the
combustion chamber 58 and the pulse combustion system 36 as a
whole. The cyclical pressure pulses result in alternating positive
and negative pressure in the combustion chamber 58, thereby
allowing additional air and fuel to be drawn into the combustion
chamber 58 for subsequent ignitions.
[0017] With reference to FIG. 1, the inlet air vent 14 is
configured to deliver air from an atmosphere vent to the inlet air
decoupler 18 through inlet air piping 22. The inlet air piping 22
is manufactured from PVC piping; although in other embodiments,
other suitable materials may be used. The inlet air decoupler 18 is
configured to provide acoustic control or disengagement of the
inlet air, such that the inlet air piping 22 configuration does not
affect the overall acoustic resonance of the combustion system 36.
The inlet air decoupler 18 is coupled to the blower 26 with
additional inlet air piping 22 configured to deliver the inlet air
to the blower 26. The blower 26 operates at an rpm as determined by
the system requirements.
[0018] As shown in FIG. 2, the generally cylindrical tank 38 has a
dome-shaped upper head 66 and is preferably formed of corrosion
resistant material, such as glass coated steel. The water tank 38
has a tank wall 70 defining an interior space 74. The water tank 38
is adapted to contain water to be heated. The tank extension 34
includes an extension wall 78, the air chamber 30, and at least a
portion of the combustion system 36, which includes the combustion
chamber 58 and an exhaust tube arrangement 82. The tank extension
34 includes a flange 86 that is detachably mounted to a flange 90
of the tank wall 70 with fasteners. The extension wall 78 defines
an extension space 92 (see FIGS. 2 and 3) that is configured to
communicate with and be flooded with water from the interior space
74 of the water tank 38. The tank extension 34 further defines an
extension axis 94. The extension axis 94 extends along a
longitudinal length of the tank extension 34.
[0019] The tank extension 34 provides additional space to
accommodate the combustion chamber 58 and at least a portion of the
exhaust tube arrangement 82. In the illustrated embodiment, the
exhaust tube arrangement 82 includes coils of tubes that facilitate
heat exchange from the products of combustion to the water
surrounding the exhaust tubes 82. The combustion chamber 58 is also
submerged in water in the tank extension 34 and provides heat
exchange to the surrounding water. Accordingly, the heat exchange
capacity of the water heater is greater than the heat exchange
capacity of a water heater without the flooded tank extension
because the flooded tank extension provides for additional space
for heat exchange. In further embodiments, the tank extension is
extendible to accommodate additional exhaust tubes for increased
heat exchange with the water surrounding the exhaust tubes. The
tank extension 34 can extend from other areas of the water tank as
long as the water heater 10 and combustion system 36 can still
effectively and efficiently operate. The tank extension 34 may
include a wall 96 (FIG. 3) at flange 44 separating the exhaust
decoupler 42 from the extension space 92 to prevent flooding of the
exhaust decoupler 42.
[0020] With additional reference to FIGS. 2 and 3, the air chamber
30 is partially disposed in the extension space 92 and extends
through the extension wall 78 in a direction substantially
perpendicular to the extension axis 94 of the tank extension 34.
The air chamber 30 may extend through the extension wall 78 at any
radial angle, and preferably extends substantially perpendicular to
the extension axis 94 of the tank extension 34 to minimize the
portion of the air chamber 30 within the extension space 92.
Extending the air chamber 30 through the extension wall 78 provides
more space in the extension space 92 for exhaust tubes 82 when
compared to containing the entire air chamber 30 within the tank
extension 34. This may provide more space for additional tubes 82
and heat exchange surfaces. The air chamber 30 includes an upper
chamber or decoupler 98, and a lower chamber 102. The decoupler 98
receives air from the blower 26 and decouples the air from pressure
pulses created during operation of the pulse combustion system 36.
An air inlet tube 106 having a smaller diameter than the diameter
of the air decoupler 98 extends through the air chamber 30 and is
coupled to the combustion system 36 to limit the amount of air
delivered to the combustion system 36. The air inlet tube 106 is
configured as an aerodynamic valve that prevents pulsations created
by the combustion process from being relieved in a reverse
direction through the air inlet tube 106 and also provides a
conduit for air to enter the combustion system 36.
[0021] FIGS. 5 and 6 illustrate configurations for air inlet tube
106A, 106B which provide additional pressure drop during the
positive pressure cycle of the combustion process. FIG. 5 shows the
air inlet tube 106A divided into smaller passages by way of a
plurality of smaller air tubes 110a, 110b, 110c, 110d, 110e, 110f,
110g positioned within the air inlet tube 106A that are configured
to collectively cause additional pressure drop to counteract
increased gas velocity created by the detonation and expansion of
fuel in the combustion chamber 58. The air tubes may extend the
full length or a partial length of the air inlet tube. The
additional pressure drop during the expansion phase may improve
combustion quality and reduce noise from the inlet air side of the
system. FIG. 6 shows another embodiment of the air inlet tube 106B
having a series of concentric or nested tubes 110h, 110i, 110j of
increasingly smaller diameter that are configured to collectively
cause additional pressure drop within the air inlet tube 106B.
[0022] As shown in FIG. 3, the combustion chamber 58 of the
combustion system 36 is at least partially disposed in the
extension space 92 and in fluid communication with the air chamber
30 to receive air from the air inlet tube 106. The combustion
chamber 58 is configured to receive air and fuel for combustion.
The water heater system 10 further includes an igniter tube 114, a
flame sensor tube 118, and a fuel delivery tube 120.
[0023] The igniter tube 114 and flame sensor tube 118 are adapted
to provide access to the combustion system 36 through the extension
wall 78 for an igniter and a flame sensor, respectively. The
igniter may include a spark igniter, a hot surface igniter, or any
other suitable igniter for the type of fuel and combustion system
36 in the water heater 10. The flame sensor is used by a control
system of the water heater to monitor the combustion state within
the combustion system 36. The fuel delivery tube 120 communicates
with the fuel nozzle 62 to facilitate delivery of fuel through the
extension wall to the combustion system 36. The fuel delivery tube
120 may be adapted for supplying natural gas, propane gas, or
another suitable fuel for the application. The tubes 114, 118, 120
also facilitate service of the igniter, flame sensor, and fuel
nozzle by providing access to them from outside the tank extension
34.
[0024] Turning now to FIG. 4, the fuel train assembly 54 includes,
in addition to the already-mentioned nozzle 62, a regulator 122, a
first shut-off valve 126, a gas expansion chamber 130, a gas
flapper valve 134, a second shut-off valve 138, and an orifice 142.
During normal operation, the fuel flows in a direction 143. The
regulator 122 is configured to control the delivery pressure of the
fuel as it passes through a first supply line, or piping 146A, to
the gas expansion chamber 130. The first gas shut-off valve 126 is
a solenoid valve in the illustrated embodiment, although it can
take the form of a slow-opening valve or any suitable valve in
other embodiments. The first gas shut-off valve 126 is positioned
upstream of the gas expansion chamber 130 and is configured to
control the flow of fuel to the gas expansion chamber 130. The
first gas shut-off valve 126 is operable between a closed position,
wherein fuel is not allowed to flow through the valve 126, and an
open position, wherein fuel is allowed to flow through the valve
126.
[0025] The gas expansion chamber 130 functions as a holding tank
for fuel and as a plenum chamber, thereby providing a dampening
effect on pulsations caused by feedback from the rapid expansion
and contraction of fuel in the combustion chamber 58 during the
pulse combustion operation. The combustion system 36 may experience
a pressure change of 1 psi during the pressure pulses. The
expansion chamber 130 retains fuel during standby to enable fuel
flow upon ignition without delay or interruption. Fuel is delivered
out of the gas expansion chamber 130 and through the remainder of
the fuel train assembly 54 as dictated by the demands of the pulse
combustion system 36. The dampening effect of the expansion gas
chamber 130 prevents any unintended pressure changes upstream of
the gas expansion chamber 130 in the upstream direction resulting
from feedback from the pulse combustion and also prevents the
products of combustion from traveling upstream of the gas expansion
chamber 130.
[0026] The gas flapper valve 134 is a one-way valve configured for
flow of fuel in a downstream direction. The gas flapper valve 134
is configured to open and close based on the pressure changes
created in the combustion system 36 during the pulse combustion
process. In operation, rapid expansion of the fuel during ignition
in the combustion chamber 58 creates increased pressure in the fuel
train assembly 54. The increased pressure closes the gas flapper
valve 134. The closed gas flapper valve 134 minimizes pressure
pulses from entering the expansion chamber 130 through the gas
flapper valve 134. As combustion consumes the fuel, the pressure
decreases, thereby allowing the gas flapper valve 134 to open. The
open gas flapper valve 134 allows fuel to flow from the gas
expansion chamber 130 through the remaining portion of the fuel
train assembly 54 to facilitate the combustion.
[0027] The fuel train assembly 54 may use a single gas flapper
valve. However, in other embodiments and as shown in FIG. 7,
multiples of a single gas flapper valve 134 can be used in a gas
flapper holder 148 to achieve a variety of inputs as required by
the particular application. The gas flapper valve is configured for
inputs up to approximately 350,000 BTUH. For example, for inputs
less than 300,000 BTUH, one gas flapper valve and expansion chamber
are used. However, for inputs between 300,000 and 700,000 BTUH, two
flapper valves are used with the expansion chamber. In other
embodiments, more than two flapper valves may be used for inputs
greater than 700,000 BTUH. The number of gas flapper valves can be
adjusted according to the input required by the particular water
heater system application. Apertures 149 integrally formed in the
holder 148 are configured to receive flapper valves 134. The
apertures 149 are blocked off if not in receipt of a flapper valve
134. Similarly, the gas expansion chamber is designed to accept a
number of gas flapper valves depending on the desired throughput of
the application.
[0028] The second gas shut-off valve 138 is a solenoid valve;
however, in other embodiments, the second gas shut-off valve may be
a slow-opening valve or any suitable valve. The second gas shut-off
valve 138 is positioned downstream of both the gas expansion
chamber 130 and the gas flapper valve 134 and configured to
minimize gas leakage through the second supply line, or piping
146B, when the pulse combustion system 36 is in standby or not in
operation. In other embodiments, the second gas shut-off valve 138
may be positioned downstream of the gas expansion chamber 130 and
upstream of the gas flapper valve 134. The second gas shut-off
valve 138 is also configured to maintain the fuel in the piping
146B during standby, such that when the system is operational, the
fuel is already pressurized in the piping 146B and prepared for
delivery to the combustion system 36. Accordingly, the second gas
shut-off valve 138 improves ignition because the second shut-off
valve 138 maintains the pressurized fuel in piping 146B during
standby. The first and second shut-off valves 126, 138 are closed
during standby to prevent gas from leaking into the combustion
system 36 when the system is not in operation. Such leakage into
the combustion system 36 when the system is not in operation could
result in leakage of fuel out of the blower 26 or through the
exhaust venting system. The fuel train assembly 54 further includes
the orifice 142 configured to restrict the flow of fuel before the
fuel is delivered to the fuel nozzle 62, such that the orifice 142
provides a further control on the flow rate of fuel through the
fuel nozzle 62 to the combustion chamber 58 of the combustion
system 36.
[0029] Each of the exhaust tubes 82 is configured to receive the
products of combustion. The exhaust tubes 82 extend into the
interior space 74 of the water tank 38. The exhaust tubes 82 are
bundled in pairs to provide efficient heat exchange in the
condensed space of the water tank 38.
[0030] Each of the exhaust tubes 82 communicates at a first end 150
with a combustion manifold 154 and at a second, opposite end 158
with an exhaust manifold 162. The combustion manifold 154 extends
into the interior space 74 of the water tank 38 and is configured
to receive and distribute the products of combustion to each of the
exhaust tubes 82. The exhaust manifold 162 receives products of
combustion from each of the exhaust tubes 82 and delivers the
products of combustion to the exhaust decoupler 42. The exhaust
manifold 162 extends through the wall 96 (see FIG. 3), but is
sealed with respect to the wall so that water in the extension
space 92 cannot flow into the exhaust decoupler 42.
[0031] The exhaust decoupler 42 receives the products of combustion
and expands the products of combustion to reduce pressure and
decouple the products of combustion from the pressure pulses
arising from pulse combustion. An exhaust gas outlet 166 extends
from the exhaust decoupler 42 and provides an outlet for exhaust
gas, while the condensate drains from a drain aperture 168 separate
from the exhaust gas outlet 166. The muffler 50 is coupled to the
exhaust gas outlet 166 with exhaust piping 46. The muffler 50 is
configured to reduce noise produced within the system. Additional
exhaust piping 46 connects the muffler 50 to an external vent
configured to release the exhaust gas external of the water heater
system 10.
[0032] In operation, an electronic control provides an ignition
sequence, water temperature control, and safety system. A sensed
drop in water temperature initiates the ignition sequence, which
begins with activation of the blower 26 to purge the combustion
system 36. The blower 26 then decreases in rpm and the ignition
system activates. The blower rpm is lowered because a lower rpm
from the blower 26 may improve ignition. The ignition system is
activated prior to opening of the gas shut-off valves 126, 138 and
subsequent delivery of fuel to the combustion system 36. Once the
gas shut-off valves 126, 138 are opened, fuel enters the combustion
chamber 58 and is ignited by the igniter. Once this process is
started, the pulsating combustion is sustained as a result of the
acoustic resonance of the combustion system 36 as a whole. The
flame sensor monitors the existence of the flame throughout
combustion. Following ignition, the blower rpm may be increased,
and the blower 26 remains operational throughout combustion. The
electronic control substantially simultaneously adjusts the first
and second gas shut-off valves 126, 138 between an open position,
in which fuel flows through both valves, and a closed position, in
which fuel does not flow through either valve, based on the demands
of the system 10.
[0033] Air is delivered by the air chamber 30 and air inlet tube
106 to the combustion chamber 58 of the combustion system 36 where
the air is mixed with fuel provided by the fuel train assembly 54.
Following ignition of the air/fuel mixture, the products of
combustion enter the combustion manifold 154. The combustion
manifold 154 distributes the products of combustion to each of the
exhaust tubes 82. The products of combustion proceed down each of
the exhaust tubes 82. Preferably, as much energy in the form of
heat as possible is transferred from the products of combustion to
the water in the tank 38, even to the point of permitting
condensation of the products of combustion. Any condensate drainage
flows toward the exhaust manifold 162. The exhaust manifold 162
delivers the exhaust gas and condensate drainage to the exhaust
decoupler 42. The exhaust gas exits the water heater 10 through the
exhaust gas outlet 166 and continues through the muffler 50 to the
external vent. The condensate drainage exits the exhaust decoupler
42 through a drain aperture 168 separate from the exhaust gas
outlet 166.
[0034] The system is configured to be scaleable in size for basic
input ranges from 140,000 to 2.5 million BTUH. In other
embodiments, the system may be configured to be scaleable in size
for basic input ranges less than 140,000 BTUH or greater than 2.5
million BTUH. Manifold tube lengths, tube diameters, and exhaust
tube lengths are selected for the particular application of the
water heater system and to maintain acoustic resonance of the
combustion system 36 as a whole.
[0035] In the pulse combustion system 36, the length of tubing
provides the desired acoustic resonance required for satisfactory
operation. For instance, the length and diameter of the inlet air
piping 22 is adjustable between the inlet air decoupler 18 and the
blower 26. Such adjustment of the length and diameter of the inlet
air piping 22 provides an additional tuning method for the pulse
combustion system 36 to obtain a desired resonance. Tuning can also
be accomplished by providing or adjusting the length and diameter
of tubing between the blower 26 and the air decoupler 98 or by
adjusting the manifold tube lengths, tube diameters, or exhaust
tube lengths.
[0036] The length of the air chamber 30 and the size of the air
decoupler 98 are determined by the requirements of the pulse
combustion system 36 and water heater 10 application. Furthermore,
the tank extension 34 and components of the fuel train assembly 54
and the combustion system 36 can be of various sizes to accommodate
different heating capacities and applications.
[0037] Various features and advantages of the invention are set
forth in the following claims.
* * * * *