U.S. patent number 3,591,150 [Application Number 04/791,883] was granted by the patent office on 1971-07-06 for gas furnace.
This patent grant is currently assigned to Weather-Rite, Inc.. Invention is credited to Richard Weatherston.
United States Patent |
3,591,150 |
Weatherston |
July 6, 1971 |
GAS FURNACE
Abstract
A gas furnace capable of maintaining a constant pressure
differential across a burner unit irrespective of changes in the
flow of air through the furnace by the use of a controlled bypass
damper adjacent the burner unit. Additional features includes
controlling the volume of air at the discharge end of the furnace,
thus, affording improved fan efficiency, a capability to circulate
air through the furnace without heating when no heat is required,
and a circuit designed to protect the furnace from air circulation
when the incoming air is below a predetermined temperature.
Inventors: |
Weatherston; Richard (St. Paul,
MN) |
Assignee: |
Weather-Rite, Inc. (Ramsey,
MN)
|
Family
ID: |
25155081 |
Appl.
No.: |
04/791,883 |
Filed: |
January 15, 1969 |
Current U.S.
Class: |
432/47; 431/19;
432/222; 126/110C; 432/48 |
Current CPC
Class: |
F23D
14/34 (20130101); F24H 3/0488 (20130101); F23D
14/60 (20130101); Y02B 30/00 (20130101); Y02B
30/28 (20130101) |
Current International
Class: |
F23D
14/60 (20060101); F23D 14/46 (20060101); F23D
14/00 (20060101); F24H 3/04 (20060101); F23D
14/34 (20060101); F23l 009/04 (); F24h
003/04 () |
Field of
Search: |
;126/11C ;263/19A
;431/19 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Claims
I claim:
1. A gas furnace including:
a furnace housing having an air inlet and an air outlet
means for circulating air through said housing,
damper means controlling the flow of air from said outlet,
a burner secured within said housing adjacent to said inlet,
profile damper means in said housing for controlling the proportion
of air passing through said housing which bypasses said burner,
and
differential pressure actuated means connected to said profile
dampers and operable to maintain a predetermined differential
pressure on opposite sides of said profile dampers.
2. The structure of claim 1 and in which said burner comprises an
elongated burner manifold, and in which said profile damper means
are mounted above and below said burner manifold.
3. The structure of claim 1 and in which said air circulating means
is in said housing.
4. The structure of claim 1 and in which said damper means
controlling the flow of air from said outlet is normally closed
unless said air-circulating means is in operation.
5. The structure of claim 1 and including remote control means for
regulating the position of said damper means controlling the flow
of air through said outlet.
6. The structure of claim 5 and including auxiliary means for
opening said damper means controlling the flow of air from said
outlet.
7. The structure of claim 1 and including means preventing the
operation of said air circulation means in the event the incoming
air is below a predetermined minimum temperature.
8. A gas furnace including:
a furnace housing having an air inlet and an air outlet,
means for circulating air through said housing,
damper means controlling the discharge of air from said outlet,
a damper control motor for controlling the position of said damper
means,
remote control means connected to said motor for adjusting the
position of said damper means,
a burner in said housing adjoining the inlet end thereof including
gas supply means providing fuel thereto,
profile damper means in said housing for controlling the flow of
air which bypasses said burner,
second motor means connected to said profile damper means for
opening and closing the same,
means actuated by differential pressure on opposite sides of said
profile damper means connected to said second motor means and
controlling the position of said profile dampers dependent upon the
pressure on opposite sides thereof.
9. The structure of claim 8 and including a circuit to said
air-circulating means for actuating the same, and means in said
circuit operable when the air entering said housing goes below a
predetermined minimum to open said circuit.
10. The structure of claim 8 and including an
auxiliary means for actuating said damper means controlling the
flow of air from said outlet.
11. A gas furnace including:
a furnace housing including an air inlet and an air outlet,
means for circulating air through said housing,
a burner mounted near the inlet end of said housing and including a
burner enclosure, a burner manifold extending across said
enclosure, and foraminous baffle plates on either side of said
burner manifold within said enclosure through which air may flow to
support combustion,
damper means controlling the flow of air through said housing
outlet,
profile damper means in said housing inlet regulating the
proportion of air entering said housing which bypasses said burner
enclosure,
means controlled by variations in differential pressure on opposite
sides of said burner connected to said profile dampers to control
the same.
12. The structure of claim 11 and in which said profile damper
means are on opposite sides of said burner enclosure.
13. The structure of claim 11 and in which said burner enclosure
are laterally elongated, and in which said profile damper means are
above and below said burner enclosure.
14. The structure of claim 13 and in which said means controlled by
variations in differential pressure operate said profile damper
means in unison.
15. The structure of claim 11 and including remote controlled means
for actuating said damper means controlling the flow of air through
said outlet.
Description
This invention relates to an improvement in gas furnace and deals
particularly with a furnace which is very efficient, and which is
capable of maintaining a pressure differential on opposite sides of
the heater unit so that the proper amount of air is supplied to
provide complete combustion depending upon the air required to heat
the area to be heated.
A feature of the present invention resides in the provision of a
furnace which includes a closed cabinet, one end of which is
preferably supplied with fresh air externally of the building or
area being heated. The entering air moves past a heater element to
which gas is supplied as the fuel being expended, and where air is
proportioned in sufficient quantity to mix with the gas to cause
virtually complete combustion. The amount of air being exhausted
from the unit depends upon the amount of air which is required to
produce the necessary heat for heating the area. In the present
arrangement, the heated air leaving the heating unit is controlled
by dampers which may be manually controlled by adjustable control
means, or which may be automatically controlled in the event the
area being heated is subject to the operation of exhaust fans which
divert a portion of the air to the outer atmosphere. In other
words, if the area being heated includes spray paint booths or
similar areas from which the air must be evacuated to outer
atmosphere, the outlet dampers may, if desired, by controlled to
replace the air removed with heated incoming air by operating these
outlet dampers.
A feature of the present invention resides in the provision of a
heater element capable of admitting air, and profile dampers
capable of admitting unheated air about the periphery of the
heater. The pressure differential on opposite sides of the burner
is maintained in such a manner that if a relatively small volume of
heated air is required, the profile dampers will tend to open so
that a greater amount of unheated air is admitted to mix with the
heated air leaving the furnace.
A further feature of the present invention resides in the provision
of a device of the type described in which air may be circulated
through the furnace to the building to provide ventilation thereto
when no heat is required. The arrangement is such that when no heat
is required, air may be circulated from the outer atmosphere to the
building through the furnace unit without requiring the
intermediate heating step.
The exhaust conditions in modern plants are constantly changing.
Factors that effect the amount of fresh air needed to replace the
exhausted air are wind direction, temperature, the condition of the
filters, and the number of exhaust fans being used. The present
device is designed to assure the right amount of air at all times.
The present device employs a constant speed drive including the
burner unit through which a desired amount of air may flow from
which the air may be discharged into the area to be heated. The
discharge or volume dampers regulate the total amount of air
delivered by changing the resistance in the system.
The dampers which are located above and below the burner compensate
for the change in air flow across the burner, and these dampers
open or close to maintain maximum combustion efficiency. In the
present arrangement, it is possible to preset or dial any volume if
air desired from the discharge dampers from 30 percent of capacity
to one hundred of capacity of the air-circulating fans.
When the amount of air being delivered to the area to be heated
changes, so does the airflow and pressure drop across the burner.
The present device operates at its peak efficiency with 0.22 inches
of air resistance across the burner. A sensitive constant
controller detects the change in airflow and automatically resets
the profile damper plates which are above and below the burner
unit, to insure maximum combustion efficiency.
The profile dampers positioned by the constant pressure control
also compensate for clogged filters that create added resistance,
wind direction that effects the amount of air being handled, and
compensate for pressure changes caused by varying burner efficiency
at all times. As a result, the device cuts heating and electrical
cost, and allows control to be effectively maintained.
These and other objects and novel features of the present invention
will be more clearly and fully set forth in the following
specification and claims .
In the drawings forming a part of the specification.
FIG. 1 is a plan view of the furnace showing the general
arrangement of parts therein.
FIG. 2 is a vertical sectional view through the furnace unit, the
position of the section being indicated generally by the line 2-2
of FIG. 1.
FIG. 3 is a perspective view of the burner unit.
FIG. 4 is a wiring diagram showing the manner in which the device
functions.
FIG. 5 is a cross-sectional view through the burner.
FIG. 6 is a perspective view of one end of the burner extrusion
before the sealing end plates are attached thereto.
FIG. 7 is a diagrammatic view of the gas system of the burner
feeding gas to the pilot and main burners.
FIG. 1 of the drawings indicates a generally rectangular outer
housing 10 which is connected at its inlet end with a filter
section 11 through which the incoming air may flow. While the inlet
end of the furnace housing is shown as being open, this end of the
furnace is usually connected by suitable duct work to the outer
atmosphere so that the air entering the furnace is normally outside
air drawn from the exterior of the building to be heated.
As is indicated in FIGS. 1 and 3 of the drawings, a panel 12
extends across the furnace housing between the sidewalls, between
the sidewalls 13 and 14 thereof, and between the top wall 15 and
bottom wall 16. The panel 12 is apertured as indicated at 17, and a
flange 19 which extends parallel to the sidewalls 13 and 14 extends
forwardly from the panel 12 on one side of the aperture 17, and a
flange 19 extends forwardly from the panel 12 along the opposite
side of the aperture 17. The flange 19 preferably is provided with
a right angularly extending baffle flange 20 which is directed
toward the sidewall 13 and acts to protect the profile damper motor
and the pressure sensor from direct contact with the heated
air.
A pair of shafts 21 and 22 extend transversely across the apertures
17 near the upper and lower edges thereof respectively. These
shafts 21 and 22 support profile dampers 23 and 24 respectively
which are rotated in unison by the damper motor. Crank arms 25 and
26 are provided on the shafts 21 and 22 respectively, and these
crank arms are connected by links 27 and 29 to an arm 30 mounted
upon the drive shaft 31 of the profile damper motor 32. Rotation of
the drive shaft 31 in one direction tends to pivot the dampers 23
and 24 into substantially parallel relation to the vertical panel
12. Rotation of the drive shaft 31 in the opposite direction is
capable of moving the dampers 23 and 25 into fully open position at
right angles to the vertical position thereof. The position of the
dampers 24 and 24 determines the proportion of air entering the
housing 10 which passes through the heater unit which is indicated
in general by the numeral 33 to the total amount of air
circulated.
The burner element includes an elongated extrusion 34 which is
supported by suitable bracket means, not illustrated in the
drawings, by the sidewalls 13 and 14 of the housing 10. The
extrusion 34 is of generally rectangular cross section and is
hollow, (See FIGS. 5 and 6), the extrusion including an upper
manifold 35 and a lower manifold 36 separated by a partition wall
37. As is indicated in FIGS. 5 and 6 of the drawings, the extrusion
34 includes substantially parallel top and bottom walls 39 and 40,
a rear wall 41, and a front wall 42. The downstream side of the
burner element is provided with a row of openings 43 which
communicate with the upper manifold 35, and a second row of
apertures 44 which are in communication with the lower manifold 36.
Gas supply lines such as 45 supply gas to the upper manifold 35
while a similar gas supply line is connected to the lower manifold
36. The gas in the manifold 36 is normally under relatively low
pressure and the gas leaving the manifold 36 through the outlet
apertures 44 are normally of low flame capacity and serve mainly as
pilot burners for the gas flowing through the discharge openings 43
connected to the upper manifold 35. The gas flowing through the
upper manifold 35 is under relatively high pressure, and is
normally turned on and off intermittently to heat the air flowing
from the furnace.
As indicated in FIGS. 1 and 5 of the drawings, the extrusion 34
supports a pair of parallel end panels 45 and an intermediate
partition plate 46. Top panels 47 and a bottom panel 49 combine
with the end plates 45 and partition plate 46 to provide a
generally rectangular passage way, the top and bottom walls of
which are in spaced relation to the extrusion 34. A pair of
apertured of foraminous baffle plates 50 and 51 are provided on the
downstream side of the extrusion 34. Each baffle 50 includes a
vertical flange 52 which is bolted or otherwise secured to the
front flange 53 of a corresponding top panel 47 by bolts 54 or
other suitable means. The baffle 50 includes an inclined portion 55
which is directed toward the vertical center of the wall 44 of the
extrusion and which is connected at its lower end 56 to a vertical
flange 57 in spaced relation to the wall 42 of the extrusion 34.
The vertical wall 57 terminates in a horizontal flange 59 which
extends over the top wall 39 of the extrusion 34 and is secured
thereto by bolts 60 or other suitable means.
In a similar manner, the baffle 51 includes a downwardly extending
vertical flange 61 which is secured by bolts or other suitable
means to the downturned vertical flange 63 of the bottom panel 49.
The flange 61 is connected to an inclined portion 64 which is
directed toward the vertical center of the extrusion side 41 and
terminates in an edge 65 which is in spaced relation to the upper
baffle end 56 to provide a throat 66 therebetween. A downturned
vertical flange 67 which is in spaced relation to the wall 42 of
the extrusion 34 terminates in a horizontal flange 67 which extends
beneath the wall 40 of the extrusion 34 and is secured in place by
means of capscrews 69 of other suitable means.
The flames caused by ignition of the gas passing through the
apertures 43 communicating with the upper manifold 35 directed
through the throat 66 between the baffles 50 and 51, and air forced
through the apertures in the baffles 50 and 51 combine with the gas
to insure complete combustion thereof. The flame heats the air as
it is drawn through the furnace housing.
It will be noted that the apertures 44 which communicate with the
low pressure manifold 36 terminate inwardly of the vertical flange
67 of the lower baffle 51 so that the flames issuing from these
apertures 44 are confined between the baffles and the
extrusion.
The air is drawn through the housing 14 by means of a pair of
axially spaced fans 71 which draw air from the housing 14 and
direct the air through transversely elongated generally rectangular
tubular outlet passages such as 72 mounted on the wall 73 at the
discharge end of the furnace housing. The fans 71 are driven by any
suitable means, and are shown as mounted upon a common shaft 74
having a pulley or sprocket 75 thereon which is connected by a
suitable belt or chain 76 to a cooperable pulley or a sprocket 77
on the drive shaft 79 of the drive blower motor 80. This
arrangement may be indicated in FIG. 1 of the drawings.
Each tubular outlet 72 communicates with an outlet aperture such as
81 in the housing panel 73. Each of the tubular outlets 72 is
provided with a series of louvers 82 mounted on parallel shafts 83
between the opposite sides of the tubular members 72. Arms 84 which
rotate with the louvers 82 are hingedly connected to a vertical
link 85 to insure of pivotal movement of the louvers from open to
closed position in unison. The operating link 84 is connected to a
crank arm 86 pivotally supported at 87 and connected by suitable
linkage to a discharge damper motor 87 located between the outlet
passages 72 as indicated in FIG. 1 of the drawings. In view of the
fact that the manner in which a reversible motor such as 87 may
drive a shaft 87 to rotate the crank arm 86 in either direction is
well known in the art, the detail of this structure is not
indicated. However, as an example, the motor 87 may be connected by
belt or chain means to a pulley or sprocket on the shaft 87 to
slowly rotate the shaft in either direction. By operation of the
motor 87, the outlet or discharge dampers may be rotated from a
fully closed position to a fully open position in which the louvers
are parallel to the direction of flow of air through the outlet
passages.
The circuit by means of which the present device is operated is
best illustrated in FIG. 4 of the drawings. As is indicated in this
figure, a circuit of generally 110--120 volts is indicated with
line wires H and G representing what is normally known in the trade
as the hot line and the ground wire. The hot line H is provided
with a fuse 90 to protect the circuit. Beyond the fuse 90 from the
current supply source, a conductor 91 connects the line wires H and
G including a signal light 92 which indicates that the power is on,
and which is illuminated when the circuit is energized through a
suitable main switching arrangement which is not illustrated in the
drawings.
A conductor 93 extends from the line wire H to line wire G and
includes a transformer coil 94 of a transformer 95. The transformer
95 is designed to transform the voltage from 110 volts between the
line wires H and G to a lower voltage such as 24 volts in the
secondary coil 96. One terminal of the coil 96 leads through a
normally closed switch 97 to a conductor 99 leading to a time delay
relay coil 100, the other terminal of which is connected by
conductor 101 to the opposite side of the transformer secondary 96.
In actual practice, the time delay relay comprises a warp switch
which opens after a predetermined length of time. However, a time
delay relay which accomplishes the same result is illustrated.
The line wire H is directed to a manually operable switch 102 which
may be positioned in the relation shown in FIG. 4 during the summer
months, and which may be positioned in an alternate position during
the winter months. In the particular arrangement illustrated, the
switch 102 is in the summer position and closes a circuit from the
line wire H to the conductor 103. The conductor 103 is connected
through a signal light 104 to the line wire G to indicate that the
circuit is closed. The conductor 103 also leads to a low limit
relay switch 106. The purpose of this arrangement will be later
described.
As soon as the relay coil 100 is energized, a switchblade 107 is
closed closing a circuit from conductor 103 through a conductor 109
and the switch 107 to a conductor 110 leading to conductor 111
leading through a low limit signal light 112 to the line wire G.
The closing of the switch 107 also closes a circuit from line wire
G. The closing of the switch 107 also closes a circuit from line
wire H, the conductor 109, switch 107, conductors 110 and 111 to a
conductor 113 leading through a series of overload switches 114 to
a conductor 115 connected to the primary of a transformer coil 116,
of a transformer 118 the other terminal of which is connected by
conductor 117 to the line wire G. Thus the closing of the switch
107 automatically energizes circuits leading to a differential
pressure switch 32 designed to control the position of the profile
dampers on opposite sides of the burner units, and a damper motor
122 designed to control the position of the discharge dampers of
the device. The damper motor 32 which controls the profile dampers
may be the type known as motor M 604 C produced by Honeywell of
Minneapolis, Minnesota. The control unit 120 for the motor 119 is
operated by differential pressure on opposite sides of the burner,
and the numeral 120 indicates a differential pressure switch used
to control the motor 119.
The transformer 118 includes a secondary coil 121 which also
controls the damper motor used to control the dampers at the
discharge of the device. The motor 122 is a reversible type motor
controlled by a potentiometer 123. The various other components of
the circuit will be later described. In view of the fact that the
switch 102 is indicated in the position to control the flow of
unheated air during the summer time, this arrangement will first be
described.
The motor 32 drives a rotatable shaft 124 which may eventually
actuate either of a pair of limit switches 125. The coils of the
motor are connected through these limit switches 125 to contacts
126 and 127 which may be engaged by a movable contact 129 actuated
by the diaphragm device 130 which is subjected to the pressures P1
and P2 connected by conduits 131 and 132 to opposite sides of the
burner element. In other words, when the differential pressure
exceeds certain limits, the movable contact 129 will engage one of
the fixed contacts 126, 127 to move the motor 32 an angular
distance sufficient to change the differential pressure in the
sensing unit 130 and to once again center the contact 129 between
fixed contacts 126 and 127. On the other hand, if the differential
pressure on opposite sides of the burner unit decreases
sufficiently, the movable contact 129 will engage the opposite of
the contacts 126, 127, and call for a reversal of the motor 32. As
will be understood, movement of the motor 32 controls the opening
and closing of the profile dampers 23 and 24.
The motor unit controlling the outlet dampers 82 is indicated in
general by the numeral 87. The motor unit 87 includes a rotatable
motor unit 133, one terminal of which is connected by conductor 134
to the current supply. A condenser 135 is connected across the
remaining motor terminals, and these remaining terminals are
connected through limit switches 136 and 137 to conductors 139 and
140 which extend through coils 141 and 142 to a pair of contacts
143 and 144 on opposite sides of an armature 145. The armature 145
is controlled by movements of the plate 146. The armature 145 is
connected by a conductor 147 to one side of the transformer
secondary 121.
The movement of the motor element 133 is controlled by the
potentiometer 123 including a resistance coil 149, one terminal of
which is connected by the conductor 150 to a coil 153 controlling
the position of the plate 146 in a manner to move the contacts 145
into engagement with the contact 144. The other end of the
potentiometer coil 149 is connected by a conductor 155 to a coil
156 which tends to move the member 146 in the opposite direction
and to cause the contact arm 145 to engage the contact 143. The
conductor 155 leads through a pair of auxiliary potentiometers 157
and 159 which will be later described.
A temperature actuated low limit switch 160 is arranged in shunt
relation to the time delay relay switch 107. The low limit switch
160 is set to open when the temperature of the incoming air is
lower than a predetermined minimum such as 40.degree. F., and
accordingly is closed during warmer weather. When the device is
being used to circulate air during summer weather, the circulating
fans should not function if the outside temperature is below a
minimum of perhaps 40.degree. F. However, the switch 160 is
normally closed when the temperature is above the minimum desired.
It should be explained that means are provided for holding the
switch 160 closed in the event the furnace is started in extremely
cold weather. Once the furnace has been started, the interior of
the housing is maintained above the low limit temperature.
The circuit from line wire H passing through either of the switches
107 or 160 of the time delay relay 161 flows through the conductor
113 and the overload switches 114 to a conductor 162 leading to the
damper end switch 163. The louvers 82 of the outlet damper normally
close when the operating motor 122 is deenergized. As soon as
current flows through the conductors 115--117, the transformer coil
116 supplying current to the motor 122, the louvers swing toward
partially open position as determined by the potentiometer 123. The
damper end switch 163 is physically closed by the partial opening
of the damper louvers, closing a circuit to the conductor 164
leading to the relay coil 165, the other terminal of which is
connected by the conductor 166 to line wire G. The energization of
the solenoid coil 165 closes a series of three starter motor
switches leading to the blower motor 167 form the line wires L1 L2
and L3. A first auxiliary switch 169 is also closed, and a circuit
is provided from a conductor 170 connected through the switch 102
to line wire H and to a conductor 171 leading to allow limit relay
172, the other terminal of which is grounded at 173. Energization
of the relay coil 172 functions to open the switch 97 in the
circuit leading to the time delay relay and to close the switch 106
connecting the relay coil 172 through conductor 105 to the
conductor 103. Thus the switch 106 closes a holding circuit for the
relay coil 172 and this coil remains energized as long as the
auxiliary switch 169 controlled by the motor-starting relay 165 is
closed.
A secondary auxiliary switch 174 is closed by the motor relay coil
165, closing a circuit from the conductor 164 through a conductor
175 and a conductor 176 to a conductor 177 leading to ground wire G
through an indicating light 179 which indicates that the blower is
in operation. A conductor 180 is also connected to the conductor
164 and leads through an indicator light 181 to the ground line G
indicating that the dampers and damper motor 122 are in
operation.
An additional element which functions is an air switch 182
connected between the conductor 177 energized by the closing of the
second auxiliary switch 174 and which closes a circuit to the
conductor 183 connected to the ground line G through an indicating
light 184 which indicates that air is flowing through the furnace.
The remainder of the circuit is broken between contacts 185 of
manual switch 102. During winter weather, when the device is to
function as a furnace, the switch 102 is moved downwardly from the
position shown in FIG. 4 of the drawings so that the upper
conductor 186 closes the contacts 187 previously connected by the
switch blade or switch element 189, and the switch blade 189
connects the contacts 185. This closes a circuit to a conductor 190
leading to the remainder of the furnace apparatus circuit. The
conductor 190 is connected to a conductor 191 through a normally
closed low gas switch 192 which is opened only when the gas
pressure is too low to support combustion. The conductor 191 is
connected to the line wire G through a low gas indicator light
193.
A conductor 194 is connected to the conductor 191 to the line wire
G through a normally closed high gas switch 195 and an indicator
light 196 indicating that the pressure in the gas line is not
excessive. The switch 195 is only opened when the gas pressure
exceeds a predetermined maximum.
A conductor 197 is connected to the conductor 194 between the high
gas switch 195 and the indicator light 196 and extends through a
high limit switch 199 to a conductor 200 leading to the line wire G
through an indicator light 201 indicating that the high limit
switch 199 is closed. A conductor 202 is connected to the conductor
200 and supplies current through a terminal 203 of a commercial
flame safeguard control which is shown diagrammatically in the
drawings. The control 204 comprises a UVM-1 control produced by the
Combustion Control Division of the Electronics Corporation of
America located at Cambridge, Mass. Alternatively, the control 204
may be a somewhat similar control produced by Minneapolis Honeywell
of Minneapolis, Minnesota known as Control R 890 G. The control 204
is connected to a scanner 205 capable of determining the presence
of ignition flame to provide the presence of flame through the use
of an ultraviolet sensitive gas discharge tube and which opens the
circuit to the main gas valve and to the pilot valve in the event
no flame is detected after predetermined time interval. The control
204 closes an internal circuit from the power terminal 203 to a
terminal 206 connected by conductor 209 to the relay switch 210 of
a nonrecycling relay 211 to a conductor 212 leading to the primary
coil 213 of an ignition transformer 214. The other transformer coil
is connected through conductor 215 to ground wire G.
The secondary coil 216 of the ignition transformer 214 has one end
grounded as indicated at 217, and extends to a spark plug 219
capable of igniting the gas for the furnace.
The terminal 206 of the control 204 is also connected by a
conductor 200 connected to the ground wire 6 through the signal
light 221. The conductor 220 is designed to energize the pilot
valve 222 connected through conductors 223 to ground wire G. Thus
the pilot valve 222 is opened simultaneously with the operation of
the ignition spark plug 219, and functions to turn on the pilot
flames and to ignite the gas.
When a flame is detected by the scanner 205, a circuit is closed
from the power terminal 203 of the control 204 to the terminal 207
through an internal circuit. The terminal 207 is connected by a
conductor 224 leading to an indicator light 225 which is also
connected to the ground wire G. The coil of a main gas solenoid
valve 226 is connected in parallel with the detector light 225 by
conductor 227 and is energized when the terminal 207 is
energized.
A conductor 229 is connected to the terminal 207 through a portion
of the conductor 224 and leads through a normally closed relay
switch 230 through a conductor 231 leading to the coil 232 of the
nonrecycling relay 211. The other terminal of the coil 232 is
connected by conductors 233 and 234 to ground wire G. Thus the
relay 232 is energized when flame is detected by the sensor 205
opening the circuit to conductor 212 leading to the ignition
transformer and closing a circuit to a contact 234 leading through
the relay coil 232. Once the relay disengages the ignition
transformer 213, it must be manually reset.
The power transformer 95 which is connected between the line wires
H and G has its secondary coil 96 connected by conductors 236 and
237 to terminals 239 and 240 of a modulating control motor 235
which may be of the type designated as M 931 C made by Minneapolis
Honeywell of Minneapolis, Minnesota. The reversible motor element
241 of this motor opens and closes a valve in the main gas line so
as to increase and decrease the flow of gas to the burners
depending upon existing conditions. The motor unit 235 is
controlled by a remote bulb proportional temperature controller
produced by Minneapolis Honeywell of Minneapolis, Minnesota. The
flow of gas is also controlled by a proportional control 243 of the
type known as a T92 A thermostat which is also produced by
Minneapolis Honeywell. In view of the fact that these devices are
well known in the art, it is believed sufficient to say that the
flow of gas through the main valve to the burners is regulated by
the units 242 and 243 to provide a proper flow of gas and to
produce a desired ambient temperature.
The motor unit 235 and its controls 242 and 243 are set into
operation by means of a switch 244 in the motor and control
circuit. A conductor 245 leading to the conductor 244 and through
which current flows when the scanner 205 indicates the presence of
a flame closes the circuit to a relay coil 246 the other terminal
of which is grounded at 247. Activation of the coil 246 closes the
switch 244 to set the motor unit 235 and its controls in
operation.
For the purpose of identification, it should be noted that the
motor 122 which controls the dampers in the discharge of the
furnace may be of the type known as M 905 E also produced by
Minneapolis Honeywell Obviously, equivalent units could be
employed.
FIG. 7 of the drawings indicates diagrammatically the arrangement
of valves in the gasline. The gas supply line 250 includes a
manually operable plug valve 251 which may close off the entire
system. A bypass line 252 provides a gas supply to the pilot
burners through a plug valve 253 and a pressure regulating valve
254. The low pressure gas passing through the valve 254 passes
through the solenoid valve 222 and to the pilot manifold of the
burner.
The operation of the device is believed quite evident from the
foregoing description. During the summertime, when it is desired to
circulate outside air through the area to be heated, the switch 102
is positioned in its elevated position shown, bridging the contacts
187. Current flows through the transformer 95 and a circuit is
closed through the switch 97 of the low limit relay to the time
delay relay coil 102. A circuit is then closed from line wire H
through the switch 102 and switch 107 of the time delay relay
through the conductor 113 and the normally closed overload switches
114 to the conductors 115 and 117 completing the circuit to the
transformer 118 providing power to the discharge damper motor 122
and the profile damper motor 32. The motor 122 moves the dampers
from their normally closed position to a position as determined by
the setting of the potentiometer 123. When the louvers 82 of the
discharge dampers open a predetermined amount, the damper end
switch 163 is closed completing a circuit to the motor starting
relay 165 which starts the blower motor 167 into operation. The
closing of the blower motor starter switch also closes an auxiliary
switch 169 completing a circuit through a switch 102 from line wire
H through conductors 170 and 171 to a low limit relay coil 172.
This opens the circuit to the time delay relay coil 100 and closes
a holding circuit which maintains the relay 172 energized as long
as the blower motor is in operation. The second auxiliary switch
174 closes a holding circuit to the motor-starting relay 165
maintaining the blower motor in operation as long as the overload
safety switches 114 and the thermostatically operated switch 160
are closed.
The discharge dampers are usually maintained at a position as set
by the potentiometer 123. However, if desired, remote control
switches 157 A and 159 A may be provided in the potentiometer
circuit. These switches are normally closed, but may if desired be
open in the event either or both of a pair of exhaust fans are
turned on to exhaust air from the building. In the event either or
both of the switches 157 A and 159 B are opened, the current to the
potentiometer 123 is varied, and the dampers are open to a greater
extent increasing the flow of air from the blowers. The profile
dampers are automatically operated by the damper motor 32 and the
pressure controller 122 to provide the proper flow according to the
pressure drop on opposite sides of the burner.
During winter weather, the switch 102 is adjusted in position
forming contact between the blower section of the furnace and the
heating section thereof. This connection extends through the
conductor 177, switch contacts 185 and conductor 190. In order to
actuate the burner circuit, it is necessary that the low gas switch
192, the high gas limit switch 195, and the high limit switch 199
be closed. It is also necessary that the blower motor be
functioning, as determined by the air flow switch 182. Current then
flows through the conductor 202 to the flame safeguard 204 and to
the contact 206 through the interior wiring. From the contact or
terminal 206, the current flows through conductors 220 and 223 to
the pilot valve 222 which opens the flow of gas to the pilot valve
manifold. Simultaneously current flows through the relay switch 210
to the ignition transformer 214 which fires the spark plug 219.
This circuit remains closed for a predetermined length of time. If
the scanner 205 detects flame, a circuit is also closed from the
terminal 203 through the interior wiring of the device 204 to the
terminal 207. This closes a circuit through the conductors 224 and
227 to the main gas solenoid 226 which opens this gas valve and
allows gas to flow to the high pressure gas manifold within the
burner.
Simultaneously, with the closing of the main gas valve 226, a
circuit is closed through conductor 229 and relay switch 230 to
conductors 231 leading to the relay coil 232, the other terminal
233 of which is connected by conductor 234 to line wire G.
Energization of the relay coil 232 opens the circuit to the
ignition transformer 213, and closes a holding circuit through the
relay switch 210 and conductors 231 to the relay coil 232,
providing a holding circuit which locks in place. Due to the fact
that during the winter weather, the furnace pilot lights remain on
constantly the relay 211 is arranged for manual reset once the
furnace has been turned off. The gas flow to the high pressure
manifold of the burner is controlled by modulating motor 241. This
motor opens and closes the valve in response to actuations to the
proportional temperature controller 242 and the thermostat 243
supplied more or less gas to the burner in response to the
demands.
I have described the principles of construction and operation of my
improvement in gas furnace, and while I have endeavored to set
forth the best embodiment thereof, I desire to have it understood
that changes may be made within the scope of the following claims
without departing from the spirit of my invention.
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