close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2130133

код для вставки
Sept. 13, 1938.
J, Q, HOUSE
FURNACE CONTROL DEVICE
Filed Oct. _24, 1934
2,130,133
I
2 Sheets-Sheet l
INVENTOR
BY
A.»
’”
ATTORNEYS.
Sept. 13, 1938.
_
J. Q. HOUSE _'
\
2,130,133
FURNACE CONTROL DEVICE
Filed Oct. 24, 1954
~
2 Sheets-Sheet 2
INVENTOR.
,
949
a. 14M,
47.‘- % “,4 94M
QATTORNEYJ.
Patented Sept. 13, 1938
2,130,133
UNITED STATES PATENT OFFlCE
2,130,133
FURNACE CONTROL DEVICE
John Q. House, Cleveland, Ohio, assignor to John
H. Leonard, Cleveland, Ohio, trustee
Application October 24, 1934, Serial No. 749,705
(01. 236-46)
This invention relates to a damper control which, in the present invention, is kept closed
11 Claims.
mechanism for furnaces and the like, a principal
object being to maintain uniform rates of com
bustion of predetermined intensities.
_
An equally important object is to modulate and
control the admission of air into and the dis
charge of products from the combustion chamber
in a manner such that the heat produced is
e?iciently applied, overheating of the furnace
1
eliminated, and stack losses of combustible mat
ter and heat are greatly reduced.
Another object is to prevent over checking and
consequent extinguishment of the ?re.
A more speci?c object is to provide a simple and
durable apparatus for controlling the operation
of the furnace, which apparatus has a minimum
number of working parts, may be installed readi
ly without material or expensive changes in the
furnace structure, and which operates to main
i-e tain a rate of combustion commensurate with
the amount of heat required and rate of transfer
and convection of the heat from the furnace.
Other objects and advantages will become ap
parent from the following speci?cation wherein
reference is made to the drawings, in which
, Fig. 1 is a diagrammatic side elevation of a
furnace showing an exemplary installation of the
vided.
,
It is well known that in the usual furnace, if
operating with the check damper D closed and
the inlet damper I open, the rate of combus
tion of the fuel will increase rapidly until the
exhaust ?ue F and the stack S are unduly heat
ed, due both to the direct escape of heated prod
ucts from the combustion chamber and to the
combustion in the ?ue and stack of volatile gases
carried thereinto. After a predetermined. high
temperature of the combustion chamber is
reached, air cannot pass through the jacket J
around the combustion chamber rapidly enough
to absorb the heat as rapidly as it is being pro-.
duced. Consequently, a large percentage of the
heat is lost, the furnace and ?ue are overheated,
and the discharge of heated air into the room
does not increase in an efficient ratio to the in
tensity of the heat of the furnace.
In order to control the furnace so as to over
come these disadvantages and to check the ?re '
when the ?ue gases have reached atemperature
at which radiation of heat from the radiating
Fig. 2 is a top plan view of a damper mecha
hood and combustion chamber of the furnace is
efficient in relation both to the passage of air
nism embodying the present invention, the check
thereabout and to the temperature requirements
damper being partially broken away for clear
of the rooms to be heated, the control mecha
nism of the present invention is provided.
present invention;
ness in illustration;
Fig. 3 is a vertical sectional View of the con
trol damper and operating 'mechanism and is
35 taken on a plane indicated by line 3—3 on Fig. 1;
Figs. 4 and 5 are sectional views taken on
planes indicated by the lines 4—4 and 5-5 re
spectively of Fig. 2; and
Fig. 6 is a diagrammatic illustration of the
40 electrical circuits and vapor motor which may be
used in connection with the damper mechanism,
the vapor motor being shown in section for clear
ness in illustration.
‘ Referring to Figs. 2 to 5 inclusive, the control
mechanism comprises a butter?y ?ue damper Ill
having a central bleeder vent I l and mounted on
a radially protruding shaft l2. The damper H]
is preferably of such size that, when turned to
dispose the plane of its surface transversely of
the ?ue F or portion of the stack in which dis
posed, it substantially ?lls the ?ue and blocks
the same except for the vent II and leakage
around its margins. The shaft I2 is rotatably
mounted in the wall of the ?ue F and protrudes
For the purposes of illustration, the invention
outwardly therefrom. Adjustably secured on the
is shown in connection with a generally used type
of household hot air furnace, its ‘use with other
outwardly protruding end of the shaft I2 is a
yoke having arms I3a and I32), which prefer
ably extend horizontally and are disposed gen
erally in a plane through the axis of the shaft
types of fuel burning equipment being readily
apparent therefrom.
Referring ?rst to Fig. 1, the furnace comprises
50, a combustion ‘chamber C, enclosed in the usual
air jacket J, and having a discharge ?ue F which
communicates with a suitable stack S, the stack
forming a continuation and part of the ?ue F and
the extending portion F’ of the ?ue being pro
55
at all times. An adjustable inlet damper I for
controlling the admission of air to' the combus
tion chamber through the ash door is also pro
vided with the usual adjustable check damper D
I2 and 45° to the plane of the damper l0. ,
Mounted on the ?ue F is a housing M in which
is rotatably mounted a horizontal shaft l5, which
extends parallel to the ?ue F. The housing I4
is disposed between the damper l8 and stack S,
the end of the shaft l4 nearest the damper pro
truding through the end wall of the housing. The
2
2,130,133
protruding end of the shaft I5 is provided with a
tongue |6 disposed at 90° to the shaft axis and
extending between the arms |3a and I3!) of the
yoke. Thus rotation of the shaft |5 through
about 90° swings the damper ID to open and
closed positions. For adjustment, the tongue may
be secured on the shaft |5 by a collar |6a and
set screw |6b. Secured by one end to the shaft
l5, within the housing I4, is a thermostatic bi
metal coil I1.
In one end wall of the housing I4 is a vertical
slot |8 through which an anchor lug l9 pro-_
trudes so that it may be moved along the slot
from outside the housing. The lug is provided
15 with a bolt |9a which is engaged by a wing nut
IS?) on the outside of the housing for securing the
lug in different adjusted positions. The opposite
end of the thermostatic coil I1 is ?xedly secured
to the anchor lug 19. Thus, if the lug is held in
20 a given ?xed position, the coil |‘|, upon heating
and cooling, will rotate the damper toward
closed and open positions respectively.
The ei?ciency of convection, the ratio of flue
temperatures to hood temperatures, and the rates
25 of combustion desired vary for different furnaces
and under different conditions to be met. Con
sequently it is desirable to adjust the tension on
the coil |'| so that it will operate the damper to
fully closed and open position within different
30 temperature ranges consistent with such extra
neous conditions.
This adjustment of the coil I1 is effected by
moving the anchor lug up or down, as the case
may be, and securing it in the desired position.
The portion of the housing M which accom
modates the coil I1 is preferably partitioned off
from the remainder by the partition wall 20a
and 20b‘ and the bottom wall 2| of this portion
is concave upwardly and deeper than the re
mainder of the housing so that, when the hous
ing rests upon the ?ue F, the coil accommodat
ing portion protrudes into the flue and is ren
dered more quickly responsive to the tempera
ture therein. The remainder of the bottom wall
45 of the housing | 4 may be shaped to conform to
the shape of the ?ue on which installed. The
bottom wall of the largest portion of the hous
ing |4, between the partition wall 20a and the
opposite end, is provided with an opening 22, a
50 coextensive opening being provided in the ?ue F
35
nace.
For this. purpose, an electrically respon
sive motor is provided, an electrically heated
vapor motor such as indicated at 25 in Figs. 1
and 6 being preferable.
The shaft l5 extends through the partition
wall 201) of the housing I4 and protrudes into
the supplemental portion 26 of the housing. On
the protruding end of the shaft I5 is a cam 21
which may be secured in different rotated posi
tions relative to the shaft l2 by means of a set
screw 28, the operating faces of the cam being
covered with insulating material and forming op
erating abutments for a suitable high and low
limit switch mechanism. The switch mecha
nism, in turn, comprises a high limit spring
lever 29 and a low limit lever 30, secured to the
wall 201) and suitably insulated therefrom. Each
is provided near. one end with electrical con
tactor 29a, and 300, respectively, and both are of
electrical conducting material. A common com
plementary contact element 3| is provided and
comprises a block of electrical conducting ma
terial which is secured in ?xed position on the
wall 2% and is insulated therefrom, and car
ries a contactor 3|a. The levers 29 and 30 are
so positioned that in certain rotated positions
of the shaft I5, the cam 21 engages them and
swings them to break contact, and in other ro
tatedv positions, disengages them so that they
spring back and return the contactors to effect 30
engagement of the contactors 29a and 30a with
the common contactor 3|a.
The thermostatic coil is preferably arranged
relative to the damper It) so that, at normal room
temperatures or a few degrees thereabove, the
damper will remain fully open. Upon heating,
the coil |1 rotates the damper shaft |5 to close
the damper Ill. The cam 21 is usually adjusted
so that when the damper I0 is in closed position,
the contact between the contactors 29a, 30a, and ,
3|a will be broken as shown in Fig. 4. In order
that normal tension on the coil I‘! may be
changed by» positioning the anchor lug IS with
out causing it to move the damper l0 beyond its
fully closed position when heated, a suitable
stop 32 is provided. Upon cooling of the coil H,
the cam 2‘! is rotated counter-clockwise.
The‘
longest operating face of the cam 21 operates the
low limit control lever 30 and the shorter face,
the lever 29, for purposes later to be described.
so that air may pass through the housing to the
Referring particularly to Fig. 6, the levers 29
?ue to check the draft. As stated above, the
usual check damper D is kept closed at all times.
damper 23 which swings upwardly for opening
and 30 are connected, through the lead wires 33
and 34 each in separate electrical series with an
electric heating element 35, and a step down
transformer 36, the common contactor 3|a com
the passage through the housing and which may
pleting both circuits._ The circuits, so described,
return by gravity to closed position.
are preferably of low voltage, the same being
energized by the usual 110 volt alternating cur
rent household circuit through the medium of
the transformer 36.
60
The heating element 35 is utilized to operate
the vapor motor 25, such as diagrammatically
illustrated in Fig. 6, which motor is utilized to
operate the check damper 23 and inlet damper
I. Generally, this motor consists of a closed cy
lindrical compartment in which is provided a
reciprocal piston 38. The lower end of the com
partment is contracted as indicated at 39, the
contracted portion containing a suitable highly
expansive liquid or ?uid which, when heated by 70
the element 35, will operate the piston in one
direction. A return spring 40 is provided for
Mounted on top of the housing I4 is a check
The coil I1 is such that as its temperature is
increased, it rotates the shaft l5 to swing the
60 ?ue damper ID to closed position, shown in Figs.
3 and 5. It is desirable that the check damper
be gradually opened as the damper l0 closes and
vice versa. To accomplish this result, a lever
24 is rigidly secured on the shaft I5 in position
65 to engage the underside of the damper 23 and
lift the same as the shaft rotates.
The relation
between the operation of the dampers I0 and 23
with respect to each other and with respect to
the coil |'| may be varied by bending the lever 24
to different adjusted positions as well as by shift
ing the position of the’collar |6a on the shaft l5.
In most instances, however, it is desirable to
supplement the mechanical operation of the flue
damper ID by electrical operation of the check
75 damper 23 and of the inlet damper I of the fur
returning the piston in the opposite direction.
The piston, in turn, is connected to a lever 4|
which carries an operating lever 42. One end
3
2,130,133
of the operating lever 42 is connected through
the medium of a chain 43 and suitably arranged
pulleys to the check damper 23, and the other
end of the lever 42 is similarly connected to the
inlet damper I. When the lever is moved to the
position indicated in Fig. 1, the inlet damper I
is closed and the check damper 23 opened and
when the lever is rotated to dispose vit in the
reverse position, the check damper will be moved
10 to closed position and the inlet damper I to open
position. The piston is so connected to the
lever 4| that it moves the lever 42' to position to
open the inlet damper I and close the check
damper 23 consequent upon heating of the ?uid
the passage ll. Meanwhile the low limit switch
has been opened.
In the usual furnace, air will not pass through
the jacket fast enough to absorb heat ‘e?iciently
beyond a furnace temperature of about 300° con
sequently a rate of combustion which increases
the temperature unduly beyond 300-0v dispropor
tionately increases the stack losses. However, as
this temperature is approached the damper i0 is
closed gradually so as to reduce the increase in 10
rate of combustion and, in fact, maintain a sub
stantially constant rate by reducing the effec
tive stack pull, bailling the heated gases and also
volatile matter from escape through the ?ue or
15 and closes the damper I and opens the check
stack and retaining them longer in the combus
damper I upon cooling of the ?uid. Thus any
failure in the electrical power supply will imme
diately check the furnace and eliminate ?re
hazards due to overheating.
20
Instead of the vapor driven motor, however,
any of the well known types of electrical motors
tion chamber.
commonly used for opening and closing dampers
may be utilized, the circuit thereto being varied
to meet the requirements of the particular motor,
25 all in a well known manner.
For most conditions, the normal setting of the
thermostatic coil IT is such that it will close'the
damper Ill upon reaching the stack temperature
of 400° to 450° Fahrenheit.
30
Since it is generally desirable to control the
furnace partially in response to room tempera
tures, a thermostat 45, described herein as located
in the room to beheated, though it may be re
sponsive to heat elsewhere, is provided.
The
thermostat 45 is of the type to make contact
when cool and break vcontact when heated and
is connected in series in circuit with the high
temperature limit lever 29.
Therefore, assuming both the room to ‘be
40 heated and the furnace are cool and the fire‘ is
started, the room thermostat, being cooled below
its set minimum temperature is in position to close
the circuit therethrough. The cam 21 is disposed
about horizontally and both electrical circuits to
the motor through the contactors 29a, 30a and
cm are closed and energized. The damper ID
is fully open as also is the inlet damper I, the
check damper 23 being closed. In this position
the entire stack pull is effective for increasing
‘
'
When the rate of combustion increases too
rapidly an over run in the ?ue temperature re
sults. Likewise a steady, though slower, increase
in combustion might continue even with > the 20
damper l0 closed. However, when the damper
ID has moved to the fully closed position, the
abutment cam’ 21 has engaged the lever 29 and
moved it so as to break the contact between the
contac‘tors 29a and 3m. This operation renders
the coil 35 inoperable by both limit circuits where
upon the motor operates in the reverse direction
to lower the damper I and openv the check damper
23 thus reducing the intensity of combustion to
a degree to which the heat can pass from the 30
furnace.
Upon starting a fresh ?re these operations may
be repeated several times until the surge in the
increase or decrease of combustion is gradually
reduced and a comparatively steady ?re at the
required rate for e?icient radiation is obtained.
In this condition the furnace comes primarily
under the control of the damper I0 which modu
lates the rate of increase and decrease to a sub
stantially uniform rate of combustion at the in 40
tensity for which the damper ID has been set.
However, complete checking for a long period
may extinguish the ?re, especially on a warm
day on which the room thermostat would never
close the high limit circuit. However, the cam 45
21 remains in operative engagement with the
lever 30 breaking its contact until a much lower
temperature of the coil I1 is reached, for example,
a stack temperature of 200° Fahrenheit. At this
lower temperature, the low limit circuit is ener 50
to maintain this relation while energized._ ‘If, gized to close the check damper 23 and open the
while this condition exists, the room reaches the inlet damper so as to sustain combustion at a
the rate of combustion.
The motor continues
required temperature, the thermostat 45 breaks
the circuit and the motor operates to close the
inlet damper I and open the check damper 23‘
unless the low limit switch is closed. Usually,
however, the heating of the room lags behind
the heating at the furnace and before the room
thermostat breaks contact, the damper It) be
CO comes eifective. Thus with the damper I' open
and check damper 23 closed, the entire stack
draft is effective and increases as therate of
combustion increases.
This causes an increase
in the temperature of the ?ue gases and the
65
products passing around the housing l4 and re
sults in heating the coil l1. As the coil I‘! be
comes heated, the damper ID is gradually moved
toward closed position, thus reducing the stack
pull that is effective in the combustion chamber
of the furnace and retaining the gases therein,
su?icient air bleeding in through the fuel bed
to maintain combustion of the so retained gases.
The lighter products of combustion, however,
are bled out aroundv the damper H] and vthrough
lower rate.
_
The motor 25 is preferably comparatively slow
in operation so that too rapid changes in the 55
operation of the furnace are eliminated.
For purposes of illustration, the damper l0 and
operating mechanism have been shown as in
stalled in the stack portion F near the combustion
chamber so as to be more quickly affected by 60
changes in the chamber. The structure may,
however, be placed directly in the upright or
other portion of the stack.
>
'
Usually the lever 24 permits closing of the 65
check damper 23_ before and effects opening
thereof after the temperatures at 'whichthe check
will be operated by the motor 25, so it does not
interfere with motor'operation but supplements
it. If many instance, the setting of the high 70,
and low limits is such that the lever 24 interferes
with the motor operation, the lever 24 may be
removed or bent out of place. The contactors
29a and 30a, as well as those of the room ther
mostat are preferably of the adjustable gap type 75
4
2,130,133
so that substantially any desired range of high
and low limits may be obtained.
It is apparent from the foregoing description
that a simple and effective apparatus for the
purposes recited is provided, and changes in the
structure shown may readily be made without
departing from the broad features of the inven
tion.
,
V
-
I claim:
10
I
1. In a fuel burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, an inlet air-control damper and a check
damper, a ?ue damper disposed withinsaid ?ue
and movable to different positions to vary the
15 effective size of the ?ue passage, thermostatic
means responsive to heat of the products in saidv
?ue and operably connected to the ?ue damper
for moving the same to said different positions,
an electrically operable motor means drivingly
connected to one of said ?rst named dampers for
moving the same to predetermined positions, an
electric circuit connected to said motor means
and to a'source’ of electrical power, and means
operable by said thermostatic means for energiz
25; ing and unenergizing said circuit whereby the ?ue
damper and one of said other dampers are op
erated in given relations to each other by the
the effective‘ size of. the ?ue passage, thermostatic
means responsive to heat produced by the appa
ratus operably connected to the ?ue damper for
moving the same to said different positions, an
electric circuit, electric motor means electrically
connected in said circuit and operably connected
to the inlet damper for opening the said damper
consequent upon energization of said circuit, a
switch in said circuit, and means operable conse
quent upon movement of said ?ue damper to
position restricting the ?ue passage to open said
switch for breaking the circuit therethrough,
whereby the inlet damper may be closed.
5. In a fuel burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, and a check damper, a ?ue damper dis
posed within said ?ue and movable to different
positions for varying the effective size of the ?ue
passage, thermostatic means responsive to heat
of the products in said ?ue and operably con 20
nected to the ?ue damper for moving the same to
said different positions, an electric circuit, elec
tric motor means electrically connected in said
circuit and operably connected to the check
damper for closing the same consequent upon 25
energization of said circuit, a switch in said cir
cuit, and means operable to move said ?ue
thermostatic means and motor means respec
damper to position restricting the ?ue passage
tively.
and operative to open the switch and break the
circuit therethrough when said means is operated 30
to effect said movement of the ?ue damper,
whereby the check damper may be opened, and
2. In a fuel burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, an inlet air control dampervand a check
damper, a ?ue damper disposed within said ?ue
means operable consequent upon breaking the
and movable to different positions for varying
the effective size of the ?ue passage, thermostatic
means responsive to heat of the products in said
?ue and operably connected to the ?ue damper
for moving the same to said different positions,
an electrically ‘operable motor means drivingly
said circuit to open the check damper.
6. In a control mechanism for a furnace hav 35
ing a combustion chamber, an exhaust ?ue lead
ing therefrom, an air inlet control damper and
a check damper, a ?ue damper disposed within
said ?ue and movable to different positions, elec
40. connected to one of said ?rst named dampers for
moving the same to different positions, an electric
circuit connected to said motor and to a source of
electrical power, abutment means movable by
said thermostatic means concurrently with the
?ue damper, an electric switch in said circuit,
and an operating lever thereon movable to dif
ferent positions tomake and break said circuit,
said lever being disposed in the path of travel of
said abutment means and movable thereby to
predetermined positions for effecting operation
of the damper associated with said motor means.
3. In a fuel burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, an inlet air control damper and a check
damper, a ?ue damper operatively associated
55
with the ?ue and movable to different positions
trical-1y operable, means operable when energized
for operating the» first mentioned dampers to
given positions, an electric circuit connected to
said means, a switch in said circuit, a thermo
static lever drivingly connected to. said ?ue
damper for moving the same to different posi
tions in response to temperature changes affect
ing said thermostatic lever, means operable by
the said thermostatic lever for opening said
switch, and means for returning said switch to
closed position, whereby said dampers may be
operated in predetermined relations to each
other.
.
Y
a
7. In a fuel'burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, an inlet air control damper, and a check 55
damper, a ?ue damper disposed within said ?ue
for varying the operation of the combustion
chamber, thermostatic means responsive to heat
and movable to different positions for varying
the effective size of the ?ue passage, thermo
of the products in said ?ue and operably con
static means responsive to heat from said appa
ratus for operating said ?ue damper, a, motor
operable to open the inlet damper and close the
check damper when operating in one direction
and operable to close the inlet damper and open
the check damper when moved in the opposite
direction, an electric circuit connected to said 65
motor, a switch in said circuit, said circuit, when
60 nected to the ?ue damper for moving the same
to said different positions, an electric circuit,
electric motor means electrically connected in
said circuit and operably connected to thev inlet
damper for opening the said inlet damper con
sequent upon energization of said circuit, a
switch in said circuit, and means operable con-1
sequent ‘upon movement of said ?ue damper to a
predetermined position to open said switch for
breaking the circuit therethrough, ‘whereby the
70 inlet damper may be closed.
' '
4. In a fuel burning apparatus having a com-i
bustion chamber, an exhaust ?ue leading there
from, an inlet air control damper and a check
entirely closed effecting operation of the motor
to open the inlet damper and close the check
damper, means operable by said thermostatic
means for opening said switch, and means oper~ 70
able consequent upon opening said switch to
operate said motor in the opposite direction.
damper, a ?ue damper disposed within said ?ue
8. In a control mechanism for a furnace hav
ing a combustion chamber and an exhaust ?ue
and movable to different positions for varying,
leading'therefrom, a check damper, a ?ue damper 75
5
2,130,133
disposed within said ?ue and movable to different
positions, a thermostatic lever drivingly con
nected to said ?ue damper for moving the same
to di?erent positions in response to temperature
changes a?ecting said thermostatic lever, means
operated by said thermostatic lever and drivingly
connected to the check damper for operating the
check damper concurrently with the operation
of the ?ue damper, whereby said dampers may
10 be operated in predetermined relations to each
other.
9. The combination with a fuel burning appa
ratus having a combustion chamber, an exhaust
?ue leading therefrom, a check damper and a
15 ?ue damper disposed within said ?ue and mov
able to different positions for varying the effec
tive size of the ?ue passage, of thermostatic
means directly responsive to heat from said ?ue
and operable to move both said ?ue damper and
and for opening the same when both circuits are
open, a high limit switch‘ in one of said circuits,
a low limit switch in the other circuit, means
operable consequent upon movement of said ?ue
damper to position greatly restricting the ?ue
in the high limit circuit for making and break
ing the high limit circuit independently of said
high limit switch, and means operable conse
11. In a fuel burning apparatus comprising a 15
combustion chamber, an exhaust ?ue leading
therefrom and a stack leading from said exhaust
?ue, a housing mounted on said exhaust ?ue be
tween the combustion chamber and stack, said
exhaust ?ue and housing having aligned openings
in inverse relation to each other.
10. In a fuel burning apparatus having a com
bustion chamber, an exhaust ?ue leading there
from, and a check damper, a ?ue damper dis
25 posed within said ?ue and movable to di?erent
positions for varying the e?ective size of the ?ue
passage, thermostatic means responsive to heat
communicating the interior of the ?ue and hous
ing at a point between the combustion chamber
and stack, said housing having an opening for
admitting outside atmosphere therethrough into
the ?ue, a check damper carried by the housing 25
and cooperating with said last mentioned pas
sage, a ?ue damper in said ?ue between the
housing and combustion chamber, thermostatic
including an electric motor means electrically
lever means carried by said housing in heat ex
changing relation with said ?ue, and means oper
ated by said thermostatic lever means for con
connected in said circuits and operably connected
trolling said dampers.
to the check damper for closing the same conse
quent upon energization of either of said circuits
10
quent upon movement of said ?ue damper to less
restricting position to close the high limit switch
and to a still less restricting position to close
the low limit switch.
said check damper to open and closed positions
produced by the apparatus and operably con
nected to the ?ue damper for moving the same
to said different positions, electric circuits, means
5
passage to open both said switches and break the
circuits therethrough, thermostatic switch means
JOHN Q. HOUSE.
Документ
Категория
Без категории
Просмотров
0
Размер файла
865 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа