Information
-
Patent Grant
-
6418882
-
Patent Number
6,418,882
-
Date Filed
Thursday, April 12, 200123 years ago
-
Date Issued
Tuesday, July 16, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 122 1301
- 122 1421
- 122 141
- 122 171
- 110 162
- 126 3611
- 126 3621
-
International Classifications
-
Abstract
A power vented, gas fired water heater has a main gas burner disposed within a combustion chamber partially bounded by an arrestor plate having a spaced series of flame quenching combustion air inlet openings therein. To provide for a “soft” ignition of extraneous flammable vapors entering the combustion chamber and to limit the build-up of unignited flammable vapors within the combustion chamber during non-demand periods of the water heater, a non-flame type ignition device is disposed within the combustion chamber and operated at least intermittently during such non-demand periods.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to fuel-fired heating appliances and, in a preferred embodiment thereof, more particularly provides a specially designed power vented, gas fired water heater having incorporated in its combustion chamber a non-flame type burner ignition system which operates at least intermittently during non-demand periods of the water heater to controllably ignite flammable vapors entering the combustion chamber through a flame arresting perforated plate structure.
Gas-fired residential and commercial water heaters are generally formed to include a vertical cylindrical water storage tank with a main gas burner disposed in a combustion chamber beneath the tank. The main burner is supplied with a fuel gas through a gas supply line, and combustion air through an air inlet flow path providing communication between the exterior of the water heater and the interior of the combustion chamber. In applications in which a sufficient natural draft is not available to draw hot combustion products upwardly through the flue portion of the water heater, to thereby transfer combustion heat to the water stored in its tank, a draft inducer fan is operatively coupled to the flue. Water heaters of this type, in which a fan is used to provide the necessary draft during water heating periods, are commonly referred to as power-vented water heaters.
Fuel fired water heaters extremely safe and quite reliable in operation. However, under certain circumstances extraneous flammable vapors from outside the water heater may enter the combustion chamber and be ignited therein. various proposals have previously been made to controllably ignite such extraneous vapors within the combustion chamber. one such proposal has been to provide an outer wall portion of the combustion chamber with flame quenching openings disposed therein and operative to permit ambient combustion air and extraneous flammable vapors to flow therethrough into the combustion chamber and be ignited, but preclude the reverse passage of flames through the flame quenching openings.
This proposed solution lends itself particularly well to gas fired water heaters operating under natural draft conditions and provided with standing pilot flames since extraneous flammable vapors entering the combustion chamber during non-demand periods of the water heater tend to be simply burned in a controlled manner by the standing pilot flame as they enter the combustion chamber.
However, the use of a standing pilot flame in a power vented gas fired water heater is not generally feasible since during non-demand periods of the water heater (in which the draft inducer fan is not operated), there is typically not sufficient natural draft present to exhaust the combustion products of a standing pilot flame. Instead, a spark igniter is typically provided in a power vented gas fired water heater and is operated, to light the main gas burner, only when a demand for water heating is present. Thus, during non-demand periods of the water heater, it may under certain circumstances be possible for extraneous flammable vapors to enter the combustion chamber through its arrestor plate flame quenching openings and accumulate in an unignited condition in the combustion chamber until a water heating demand signal is received to operate the spark igniter and light the main gas burner. The resulting ignition of the flammable vapors within the combustion chamber may undesirably tend to be more forceful than would be the case of a standing pilot flame maintained in the combustion chamber of a natural draft water heater.
in view of this, it would be desirable to provide a technique for more controllably igniting extraneous flammable vapors that may enter the combustion chamber of a power vented, fuel fired water heater during non-heating demand periods thereof. It is to this goal that the present invention is directed.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a power vented, fuel fired heating apparatus is provided which is representatively a gas fired water heater and comprises a combustion chamber thermally communicatable with a fluid to be heated, the combustion chamber being partially bounded by a flame arrestor portion with spaced flame quenching combustion air inlet openings therein. A fuel burner is disposed within the combustion chamber and is operable during heating demand periods of the heating apparatus, a flue is operatively communicated with the combustion chamber, and a fan is associated with the flue and is operable to create a forced draft therein during the heating demand periods of the heating apparatus.
According to a key feature of the invention, the heating apparatus also comprises ignition apparatus including a non-flame type ignition device disposed within the combustion chamber and operative at least intermittently during non-heating demand periods of the heating apparatus. In this manner, extraneous flammable vapors which may migrate into the combustion chamber via the flame quenching combustion air inlet openings in its flame arrestor portion during a non-heating demand period of the heating apparatus are ignited with a relatively soft ignition force during such non-heating demand period.
In a first illustrative embodiment of the heating apparatus, the ignition apparatus comprises a first spark igniter operative to light the fuel burner at the beginning of each heating demand period, and a second spark igniter operable intermittently (representatively at intervals of from about 15 seconds to about 30 seconds) during non-heating demand periods to provide a softened ignition for extraneous flammable vapors that might enter the combustion chamber through the flame quenching combustion air inlet openings of its flame arrestor portion.
In a second illustrative embodiment of the heating apparatus, the ignition apparatus comprises a single spark igniter which is operable at the beginning of each heating demand period to light the fuel burner, and is also operable intermittently (representatively at intervals of from about 15 seconds to about 30 seconds) during non-heating demand periods to provide a softened ignition for extraneous flammable vapors that might enter the combustion chamber through the flame quenching combustion air inlet openings of its flame arrestor portion.
In a third illustrative embodiment of the heating apparatus, the ignition apparatus comprises a spark igniter which is operable at the beginning of each heating demand period to light the fuel burner, and an auxiliary non-flame type ignition device, such as a hot surface igniter or a glow coil, which is continuously operable during non-heating demand periods to provide a softened ignition for extraneous flammable vapors that might enter the combustion chamber through the flame quenching combustion air inlet openings of its flame arrestor portion.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
schematically illustrates in simplified form a first embodiment of a power vented gas fired water heater embodying principles of the present invention;
FIG. 2
is a schematic ignition control diagram for the water heater of
FIG. 1
;
FIG. 3
schematically illustrates in simplified form a second embodiment of the power vented gas fired water heater;
FIG. 4
is a schematic ignition control diagram for the water heater of
FIG. 3
;
FIG. 5
schematically illustrates in simplified form a third embodiment of the power vented gas fired water heater; and
FIG. 6
is a schematic ignition control diagram for the water heater of FIG.
5
.
DETAILED DESCRIPTION
Schematically depicted in
FIG. 1
is a power vented, gas fired water heater
10
which embodies principles of the present invention. Water heater
10
rests on a floor
12
and has a tank portion
14
in which a quantity of heated water
16
is stored for on-demand delivery to hot water-utilizing plumbing fixtures such as sinks, showers, bathtubs, dishwashers and the like. A combustion chamber
18
is disposed beneath the tank
14
and has a main gas burner
20
, and an associated burner-lighting ignition device
22
, operatively disposed therein. A gas supply line
24
, having a thermostatically controlled valve
26
therein, is connected to the burner
20
. The burner-lighting device
22
is a conventional spark ignition device which operates when there is a demand for adding heat to the water
16
.
The bottom wall of the combustion chamber
18
is defined by an arrestor plate
28
having a spaced series of flame quenching air inlet openings
30
therein. Beneath the arrestor plate
28
is an air inlet plenum
32
that opens outwardly through a circumferentially spaced series of air inlet openings
34
formed in an annular skirt portion
36
at the lower end of the water heater
10
. A flue
38
extends upwardly from the combustion chamber
18
, through the water
16
in the tank
14
, and is communicated at its upper end with the inlet of a draft inducer fan
40
suitably mounted on the top end of the body of the water heater
10
. Fan
40
has an outlet connected to a horizontally extending vent pipe
42
.
During firing of the water heater
10
, gas is supplied to the burner
20
via the gas supply line
24
, under the control of the valve
26
, mixed with ambient combustion air
44
drawn into the combustion chamber
18
by the fan
40
(via the flame quenching openings
30
in the arrestor plate
28
) through the skirt openings
34
and the plenum
32
, and combusted with the gas by the burner
20
upon lighting thereof by the spark ignition device
22
. Resulting hot combustion products
46
flow upwardly through the flue
38
and are discharged into the vent pipe
42
by the draft inducer fan
40
which operates during firing cycles of the water heater
10
but is otherwise idle. Heat from the combustion products
46
is transferred to the water
16
.
During firing of the water heater
10
, the arrestor plate flame quenching openings
30
serve to permit flammable vapors
48
(created, for example, by a flammable liquid spill adjacent the water heater) to pass upwardly into the combustion chamber
18
and be burned therein, but prevent the downward discharge. of flames through the arrestor plate openings
30
. Arrestor plate
28
may be of any suitable construction, with an example of an arrestor plate structure incorporated in a gas-fired water heater being shown in U.S. Pat. No. 6,035,812 to Harrigill et al. As described above, the overall combustion air inlet path into the combustion chamber
18
representatively extends through the skirt openings
34
and the bottom end plenum
32
. This air inlet path to the arrestor plate, however, is merely representative and a variety of other air inlet path configurations and constructions could be employed if desired.
As in the case of conventionally constructed power vented gas fired water heaters, the spark igniter
22
is operated only when it is desired to fire the water heater
10
, and is idle during all off-duty (i.e., “non-firing”) periods of the water heater). A standing pilot flame, conventionally employed in natural draft water heaters, is typically not feasible as a main burner-lighting mechanism in a power vented gas fired water heater since there is usually not enough natural draft through the flue during non-firing periods of the water heater.
The use in a conventionally constructed power vented, gas fired water heater of a spark igniter to light the main burner presents the possibility that during off-duty (i.e., non-heating demand) periods of the water heater a quantity of flammable vapor
48
can migrate into the combustion chamber (due to a small natural draft created by the water-warmed flue
38
during non-demand periods of the water heater
10
) and build up therein until ignited by the spark igniter
22
upon the initiation of the next firing cycle. When the spark igniter
22
is subsequently activated in response to a water heating demand, an undesirably “hard” ignition of the built-up flammable vapors can occur.
According to a key aspect of the present invention, the possibility of this potentially hard ignition of flammable vapors entering the combustion chamber
18
during non-demand periods of the water heater
10
is substantially eliminated by providing within the combustion chamber
18
a second non-flame type ignition device, representatively a second spark igniter
50
, which is intermittently operated during non-demand or standby periods of the water heater
10
. Spark igniters
22
and
50
are representatively incorporated in the schematically depicted control circuit of FIG.
2
.
Referring now to
FIG. 2
, a main control system
52
is connected to the spark igniter
22
by a pairs of electrical leads
54
and
56
, and to the gas supply valve
26
by a pair of electrical leads
58
. Upon receipt of a heating demand signal
60
from the heating thermostat (not shown), the main control system
52
transmits electrical power via the leads
58
to the gas valve
26
to open it, and transmits electrical power via leads
54
to the normally idle spark igniter
22
to cause it to spark until the gas burner
20
(see
FIG. 1
) is lit. The spark igniter
22
is then returned to its normal dormant mode. Appropriate electrical signals routed through the leads
56
are used to monitor and verify proper operation of the spark igniter
22
. When the water heating demand is satisfied, and the demand signal
60
terminates, the main control system
52
terminates electrical power to the gas valve
26
, thereby causing it to return to its normally closed position to shut off the gas burner
20
.
An auxiliary control system
62
has a suitable timing section
64
which is connected to the spark igniter
50
by electrical leads
66
. Spark igniter
50
, in turn, is connected to the main control system
52
by electrical leads
68
. Appropriate electrical signals routed through the leads
68
are used to monitor and verify proper operation of the spark igniter
50
.
According to an aspect of the present invention, the auxiliary control system intermittently energizes the spark igniter
50
(representatively every 15 to 30 seconds, or at a greater or lesser time interval as conditions dictate), via leads
66
, during both demand and non-demand periods of the water heater
10
. This unique intermittent energization of the spark igniter
50
during non-firing periods of the water heater
10
provides for a “soft” ignition of flammable vapors
48
which may enter the combustion chamber
18
during standby periods of the water heater. This desirably softened ignition of flammable vapors
48
migrating into the combustion chamber
18
during off-duty periods of the water heater is achieved by substantially limiting the potential unignited flammable vapor build-up time within the combustion chamber.
A first alternate embodiment
10
a
of the previously described water heater
10
, together with associated control apparatus, are schematically illustrated in
FIGS. 3 and 4
. For ease in comparison with the previously described water heater
10
and its associated control apparatus, components of the water heater
10
a
and its control apparatus similar to their counterparts in
FIGS. 1 and 2
have been given the same reference numerals, but with the subscripts “a”.
Turning now to
FIGS. 3 and 4
, the water heater
10
a
is substantially identical to the previously described water heater
10
with the exception that in the water heater
10
a
the second spark igniter
50
and its associated auxiliary control system
62
are eliminated, and the main spark igniter
22
a
is operated in a different manner which will now be described.
As schematically illustrated in
FIG. 4
, a suitable timing section
70
is incorporated in the main control system
52
a
, with the electrical leads
54
a
(via which the spark igniter
22
a
is energized) being interconnected between the spark igniter
22
a
and the timing section
70
. In a conventional manner, the spark igniter
22
a
is energized in response to the receipt by the main control system
52
a
of the heating demand signal
60
a
. Additionally, however, the spark igniter
22
a
is intermittently energized (representatively every 15 to 30 seconds, or at a greater or lesser time interval as conditions dictate), via the timing section
70
, during non-demand periods of the water heater
10
a
. Thus, the single spark igniter
22
a
performs the functions of the two spark igniters
22
and
50
in the water heater
10
in FIG.
1
.
A second alternate embodiment
10
b
of the previously described water heater
10
, together with associated control apparatus, are schematically illustrated in
FIGS. 5 and 6
. For ease in comparison with the previously described water heater
10
and its associated control apparatus, components of the water heater
10
b
and its control apparatus similar to their counterparts in
FIGS. 1 and 2
have been given the same reference numerals, but with the subscripts “b”.
In the water heater
10
b
and its associated control apparatus shown in
FIGS. 5 and 6
, the spark igniter
50
is replaced by a continuously operative non-flame type ignition device such as a glow coil or hot surface igniter
72
. The timing section
64
is deleted from the auxiliary control system
62
b
, and the ignition device
72
is connected to the main control system
52
b
by electrical leads
74
as indicated in FIG.
6
. Appropriate electrical signals routed through the leads
74
are used to monitor and verify proper operation of the non-flame type ignition device
72
. The spark ignition device
22
b
is energized in response to receipt of the heating demand signal
60
b
by the main control system
52
b
, with the auxiliary ignition device
72
being continuously energized during both demand and non-demand periods of the water heater
10
b
. The auxiliary ignition device
72
is thus operative to continuously provide for the “soft” ignition of extraneous flammable vapors
48
b
that may migrate into the combustion chamber
18
b
during non-demand periods of the water heater
10
b.
As can be seen from the foregoing, the present invention provides, in several illustrative and non-limiting embodiments thereof, a power vented, fuel-fired water heater having a fuel burner disposed within a combustion chamber partially bounded by an arrestor structure with a spaced series of flame quenching combustion air inlet openings therein, and a non-flame type ignition device disposed within the combustion chamber and operated on at least an intermittent basis during non-demand periods of the water heater. As used herein, the phrases “operative at least intermittently”, “operative on at least an intermittent basis”, or the like, encompass both intermittent and continuous operation.
While the present invention has been representatively illustrated and described herein as being incorporated in a power vented, fuel fired water heater, it will be readily be appreciated by those of ordinary skill in this particular art that principles of the present invention could also be employed to advantage in other types of power vented, fuel fired heating appliances, such as boilers and furnaces, if desired.
The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.
Claims
- 1. Power vented, fuel fired heating apparatus comprising:a combustion chamber thermally communicatable with a fluid to be heated, said combustion chamber being partially bounded by a flame arrestor portion with spaced flame quenching combustion air inlet openings therein; a fuel burner disposed within said combustion chamber and being operable during heating demand periods of said heating apparatus; a flue operatively communicated with said combustion chamber; a fan associated with said flue and operable to create a forced draft therein during said heating demand periods; ignition apparatus including a non-flame type ignition device disposed within said combustion chamber; and control means for operating said non-flame type ignition device at least intermittently during non-heating demand periods of said heating apparatus.
- 2. The heating apparatus of claim 1 wherein said heating apparatus is a water heater.
- 3. The heating apparatus of claim 2 wherein said water heater is a gas fired water heater.
- 4. The heating apparatus of claim 1 wherein said non-flame type ignition device is intermittently operable by said control means during said non-heating demand periods.
- 5. The heating apparatus of claim 4 wherein said non-flame type ignition device is a spark igniter.
- 6. The heating apparatus of claim 4 wherein said non-flame type ignition device is additionally operable by said control means at the beginning of each heating demand period to light said fuel burner.
- 7. The heating apparatus of claim 1 wherein said non-flame type ignition device is continuously operable by said control means during said non-heating demand periods.
- 8. The heating apparatus of claim 7 wherein said non-flame type ignition device is a hot surface igniter.
- 9. The heating apparatus of claim 7 wherein said non-flame type ignition device is a glow coil.
- 10. The heating apparatus of claim 7 wherein said non-flame type ignition device is also continuously operable by said control means during said heating demand periods.
- 11. Power vented fuel fired heating apparatus comprising:a combustion chamber thermally communicatable with a fluid to be heated, said combustion chamber being partially bounded by a flame arrestor portion with spaced flame quenching combustion air Inlet openings therein; a fuel burner disposed within said combustion chamber and being operable during heating demand periods of said heating apparatus; a flue operatively communicated with said combustion chamber; a fan associated with said flue and operable to create a forced draft therein during said heating demand periods; and ignition apparatus including a non-flame type ignition device disposed within said combustion chamber and intermittently operable during non-heating demand periods of said heating apparatus, said non-flame type ignition device being intermittently operable at intervals ranging from about fifteen seconds to about thirty seconds during said non-heating demand periods.
- 12. Power vented, fuel fired heating apparatus comprising:a combustion chamber thermally communicatable with a fluid to be heated, said combustion chamber being partially bounded by a flame arrestor portion with spaced flame quenching combustion air inlet openings therein; a fuel burner disposed within said combustion chamber and being operable during heating demand periods of said heating apparatus; a flue operatively communicated with said combustion chamber; a fan associated with said flue and operable to create a forced draft therein during said heating demand periods; and Ignition apparatus including a non-flame type ignition device disposed within said combustion chamber and intermittently operable during non-heating demand periods of said heating apparatus, said non-flame type ignition device being an auxiliary non-flame type ignition device, and said ignition apparatus further including a primary non-flame type ignition device operable at the beginning of each heating demand period to light said fuel burner.
- 13. The heating apparatus of claim 12 wherein each of said primary and auxiliary non-flame type ignition devices is a spark igniter.
- 14. Power vented, fuel fired heating apparatus comprising:a combustion chamber thermally communicatable with a fluid to be heated, said combustion chamber being partially bounded by a flame arrestor portion with spaced flame quenching combustion air inlet openings therein; a fuel burner disposed within said combustion chamber and being operable during heating demand periods of said heating apparatus; a flue operatively communicated with said combustion chamber; a fan associated with said flue and operable to create a forced draft therein during said heating demand periods; and ignition apparatus including a non-flame type ignition device disposed within said combustion chamber and continuously operable during non-heating demand periods of said heating apparatus, said non-flame type ignition device being an auxiliary non-flame type ignition device, and said ignition apparatus further including a primary non-flame type ignition device operable at the beginning of each heating demand period to light said fuel burner.
- 15. The heating apparatus of claim 14 wherein:said primary non-flame type ignition device is a spark igniter, and said auxiliary non-flame type ignition device is a hot surface igniter.
- 16. The heating apparatus of claim 14 wherein:said primary non-flame type ignition device is a spark igniter, and said auxiliary non-flame type ignition device is a glow coil.
- 17. A method of operating a power vented, fuel fired heating appliance having a combustion chamber with a fuel burner therein, said method comprising the steps of:disposing a non-flame type ignition device within said combustion chamber; and operating said non-flame type ignition device at least intermittently during non-heating periods of said heating appliance.
- 18. The method of claim 17 wherein said disposing step is performed by disposing a spark igniter within said combustion chamber.
- 19. The method of claim 17 wherein said disposing step is performed by disposing a hot surface igniter within said combustion chamber.
- 20. The method of claim 17 wherein said disposing step is performed by disposing a glow coil within said combustion chamber.
- 21. The method of claim 17 wherein said operating step is performed by intermittently operating said non-flame type ignition device during said non-heating demand periods of said heating appliance.
- 22. The method of claim 17 wherein said operating step is performed by continuously operating said non-flame type ignition device during said non-heating demand periods of said heating appliance.
US Referenced Citations (5)
Number |
Name |
Date |
Kind |
4492185 |
Kendall et al. |
Jan 1985 |
A |
4925093 |
Moore, Jr. et al. |
May 1990 |
A |
5197665 |
Jenson et al. |
Mar 1993 |
A |
5697330 |
Yetman et al. |
Dec 1997 |
A |
5950573 |
Shellenberger et al. |
Sep 1999 |
A |