U.S. patent application number 10/681227 was filed with the patent office on 2005-04-14 for flammable vapour detector system for hot water heater.
Invention is credited to Lesage, Claude.
Application Number | 20050079459 10/681227 |
Document ID | / |
Family ID | 34422246 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050079459 |
Kind Code |
A1 |
Lesage, Claude |
April 14, 2005 |
Flammable vapour detector system for hot water heater
Abstract
A flammable vapour detector system is comprised of a
thermocouple which is mounted in a combustion chamber of a hot
water heater. A combustion air intake means supplies combustion air
to the combustion chamber. A gas burner is provided in the
combustion chamber. A gas supply line is secured to the gas burner.
An external gas valve is provided in the supply line. A gas valve
control circuit controls the ON/OFF state of the external gas
valve. The gas valve control circuit is connected to the
thermocouple. The thermocouple is exposed to the combustion chamber
to sense the temperature therein and is set to cause the control
circuit to shut off the external gas valve when the temperature in
the combustion chamber reaches a set predetermined temperature
value upon burning flammable vapours as they propagate in the
combustion chamber through the combustion air intake means.
Inventors: |
Lesage, Claude; (Pointe
Claire, CA) |
Correspondence
Address: |
OGILVY RENAULT
1981 MCGILL COLLEGE AVENUE
SUITE 1600
MONTREAL
QC
H3A2Y3
CA
|
Family ID: |
34422246 |
Appl. No.: |
10/681227 |
Filed: |
October 9, 2003 |
Current U.S.
Class: |
431/77 |
Current CPC
Class: |
F23N 5/107 20130101;
F23N 5/247 20130101 |
Class at
Publication: |
431/077 |
International
Class: |
F23N 005/00 |
Claims
I claim,
1. A flammable vapour detector system comprising a thermocouple
mounted in a combustion chamber of a hot water heater, combustion
air intake means to supply combustion air to said combustion
chamber, a gas burner in said chamber, a gas supply line secured to
said gas burner, an external gas valve in said supply line, a gas
valve control circuit to control the ON/OFF state of said external
gas valve, said gas valve control circuit being connected to said
thermocouple, said thermocouple being exposed to said combustion
chamber to sense the temperature therein and being set to cause the
control circuit to shut off said external gas valve when said
temperature in said combustion chamber reaches a predetermined set
temperature value upon burning flammable vapours as they propagate
in said combustion chamber through said combustion air intake
means.
2. A flammable vapour detector system as claimed in claim 1 wherein
said predetermined value is higher than the temperature generated
by said burner from the combustible gas and air mixture without
flammable vapours mixed therewith.
3. A flammable vapour detector system as claimed in claim 2 wherein
said control circuit comprises a normally closed (N.C.) switch
through which is supplied a current to maintain said gas valve open
to supply gas to said burner.
4. A flammable vapour detector system as claimed in claim 3 wherein
said thermocouple opens said N.C. switch upon sensing said
predetermined set temperature value to cut off said current to
cause said gas valve to close and shut off gas supply to said
burner to extinguish same.
5. A flammable vapour detector system as claimed in claim 2 wherein
said combustion air intake means is a snorkel having an elevated
air intake port to admit ambient combustion air to said combustion
chamber.
Description
TECHNICAL FIELD
[0001] The present invention relates to a flammable vapour detector
system for shutting off the burner of a combustion chamber located
in a hot water heater upon detection of flammable vapours within
the burner chamber.
BACKGROUND ART
[0002] Various devices have been developed in recent years for
detecting flammable gases in the area of a gas-fired hot water
heater. Most systems use gas sensors which are located in proximity
to the air intake for the combustion chamber and upon detection of
same, the burners are shut down. These sensors are capable of
sensing a variety of explosive gas, such as natural gas, methane,
propane, butane, gasoline, solvents and paints. Also, the air
intakes leading to the combustion chamber are usually elevated from
the floor surface or else the entire hot water heater is supported
on an elevated base whereby to elevate the air intake from the
floor. Regulations are in place concerning the installation of
gas-fired hot water heaters and it is recommended that they be
mounted with their air intake at least 18" from the floor surface.
Because natural gas is lighter than air, gas detectors must be
installed adjacent a ceiling close to the hot water heater whereas
detectors for heavier gases such as propane, gasoline vapours and
kerosene, are located close to the floor as these gases are heavier
than air. Accordingly, it is preferable to have two detectors
associated with such water heaters.
[0003] A problem with using gas sensors is that many of these
sensors do not operate effectively and often malfunction.
Accordingly, they are not entirely reliable. There is therefore a
need to provide a more reliable way of detecting explosive
flammable vapours.
SUMMARY OF INVENTION
[0004] It is a feature of the present invention to provide a
flammable vapour detector system which overcomes the
above-mentioned disadvantages of the prior art.
[0005] According to a broad aspect, the present invention provides
a flammable vapour detector system which comprises a thermocouple
mounted in the combustion chamber of a hot water heater. A
combustion air intake means supplies combustion air to the
combustion chamber. A gas burner is provided in the combustion
chamber. A gas supply line is secured to the gas burner. An
external gas valve is provided in the supply line. A gas valve
control circuit controls the ON/OFF state of the external gas
valve. The gas valve control circuit is connected to the
thermocouple. The thermocouple is exposed to the combustion chamber
to sense the temperature therein and is set to cause the control
circuit to shut off the external gas valve when the temperature in
the combustion chamber reaches a set predetermined temperature
value upon burning flammable vapours as they propagate in the
combustion chamber through the combustion air intake means.
BRIEF DESCRIPTION OF DRAWINGS
[0006] A preferred embodiment of the present invention will now be
described with reference to the accompanying drawings in which:
[0007] FIG. 1 is a schematic view of the flammable vapour detector
system of the present invention utilized in conjunction with a
combustion chamber of a hot water heater.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0008] Referring now to the drawing, there is shown the lower
portion 10 of a hot water heater. The schematic illustration does
not show all of the component parts of the lower end of the hot
water heater but the illustration is only schematic. Therefore, the
inner casing of the hot water heater as well as the outer casing,
pipes and controls are not illustrated.
[0009] At the lower end of the hot water heater, there is provided
a combustion chamber 11 in which there is secured a gas burner 12.
A gas line 13 supplies combustible gas, herein natural gas, to the
gas burner 12. The gas line 13 is connected to the gas supply line
14 through a main gas valve 15. Combustible air is supplied to the
combustion chamber 11 through air intake means, and as herein
shown, via a snorkel 16 which is a channel provided with an
elevated air intake port 17 whereby to admit air at a predetermined
elevation from a support floor 18 on which rests the hot water
heater 10. Accordingly, combustion air enters the inlet port and
propagates down into the snorkel to enter the combustion chamber
11. The hot water heater could also be supported on an elevating
base if the air intake is at the bottom of the heater whereby to
elevate the air intake.
[0010] The present invention provides a thermocouple 19 which is
mounted at a predetermined location within the combustion chamber
11 and which is connected to a high limit cut-off normally closed
switch 20 and they constitute a control circuit. Power supply for
the main gas valve is provided through the connection 21 from the
normally closed switch 20. The thermocouple is exposed to the
combustion chamber to sense the temperature therein and it has a
set point whereby to cause the normally closed switch to open upon
sensing the set predetermined temperature whereby to cause the main
gas valve to shut down and stop the gas supply to the burner 12. By
shutting the main gas valve, the gas supply to other appliances 25
is also shut-off to prevent explosion.
[0011] The system works as follows. As flammable vapours enter the
snorkel 16 with the air supply, they are burned by the gas burner
12 and these additional flammable vapours burn and thereby raise
the temperature in the combustion housing. The thermocouple 19 is
set to open the switch 20 upon detection of a predetermined
temperature value when flammable vapours are being burned in the
combustion chamber. Accordingly, as the temperature in the
combustion chamber rises due to infiltration of external flammable
combustible products, the main gas valve shuts down the gas supply
and the gas burner is extinguished to prevent an explosion. Other
appliances are also shut down. The predetermined temperature value
is set higher than the temperature generated by the burner from the
combustible gas and air mixture without the flammable vapours mixed
therewith.
[0012] The normally closed contact switch 20 supplies a 25
milli-amp current to the main gas valve through connection 21, to
maintain that gas valve open to supply gas to the burner. When the
current is cut off by opening the switch 20, then the main gas
valve shuts down automatically.
[0013] The above flammable vapour detector system of the present
invention is an economical, safe and efficient way of shutting down
the burner in the combustion chamber of a gas fired hot water
heater upon detection of flammable vapours and does not rely on gas
sensors which often malfunction and which require separate power
supplies.
[0014] It is within the ambit of the present invention to cover any
obvious modifications of the preferred embodiment described herein,
provided such modifications fall within the scope of the appended
claims.
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