Note: Descriptions are shown in the official language in which they were submitted.
This device relates to a damper mechanism for
opening and closing the orifice size of an exhaus-t flue
associated with a heating device such as a furnace, whether
gas or oil fired.
There are a number of automatic flue dampers
located in the vent stacX for commerical or household
furnaces or other apparatus which are designed to close the
vent stack during times when combustion within the furnace
does not occur, and to open during times when the combustion
lG is occuring in the apparatus. Normally, the open position
is controlled by a damper spring. In case of default of
electric energy the damper itself is moved to its open from
closed position; otherwise, by a direct current solenoid
associatedly connected to interface with the temperature
sensing device which operates the vent - to close it.
Such device moves, quickly, the damper from its
open to close position as a result of tha solenoid action
and this is not desirable on at least two counts; firstly,
extra associated noise with the damper reaching its limit
position from its closed to open or open to the closed
position, and secondly, the increased mechanical structure
necessary in order to stop the inertia of the quick moving
damper.
In another automatic stack damper an electric
motor is used to rotate the damper within the stack from its
open to its closed position and from the closed to its open
position either with or without a bias means that operates
the vent. Such device is clearly indicated in U,S.A. Patent
#4,039,1~3, entitled AUTOMATIC STACK DAMPER to Seymour
Frankel, issued 2 August 1977. It suffers from a number of
disadvantages which include the re~uirement that the motor
3~
operated vent be connected to a thermal sensing device such
as a thermostat located in the vent. It is the vent
thermostat which activates and deactivates the electric
motor associated with the Frankel device. Thus, the
response of the damper is immediate upon the demand of the
thermostate to call heat and at shut-ofE period. The
requirement of Frankel causes the damper to shut when the
thermostat, which senses the temperature in the room be
heated, goes off only after, the thermo sensor which is
physcially located in the exhaust flue of the furnace,
crosses below a cool-down threshold temperature which in
most instances is fixed at 400F, approximately 170C.
Particulàrly, an oil fired furnace, where the oil
fired furnace is not "tuned" and incomplete combustion
normally takes place, soot or carbon particles, are
generated by the fire of the oil fired furnace, and move out
into the exhaust flue and normally, because they also
contain residual oil particles thereon, adhere to the flue.
This causes the temperature sensor in the flue of Frankel to
be coated with temperature insulating caxbon particles.
E~ënce, the sensitivity of the sensor may become immune due
to the carbon particle coating, in which case, the flue
temperature is substantially higher than the ~00F minimum
threshold and this cause~ improper operation of the Frankel
device.
In instances where the ignition fuel is oil, there
is a tendency therefore to prematurely close the damper
while still hot escaping flue gases emanate from the fire
box since there i8 still oil in the fire box. Hence, carbon
monoxide has a tendency to dangerously accumulate.
Further, such de~ice~, because they operate to
,
close after a fairly long sustained period of time, their
ability to preserve the temperature in the fire box, or more
accurately in the boiler of the furnace is decreased because
of the extremely long period of time that elapses after
de-ignition of the furnace and closing of the vent as will
hereinafter be noted.
Although, in one sense, the Frankel thermo~sensor
in the exhaust flue may be perceived as a time delay
mechanism, this is inaccurate since the temperature sensor
creates an apparent time delay whose elapsed time is
variable and unpredicatable. This is unacceptable from two
divergent points of viewî firstly, the vent may be closed
.
too soon whereupon dangerous flue gases are trapped in the
furnace fire box7 or secondly, the vent may not close soon
enough whereupon great heat loss escapes up the exhaust flue
between the duration of de-ignition of the furnace and the
closing off of the vent. Lack of energy preservation after
de-ignition of the furnace is highly significant, in the
latter case and may even result in undisclosed inutility in
such device. The latter aspect becomes even more acute when
there is a large~cross-sectional area of the flue vent and
with a greater height of the flue stack since, as those
skilled in the art will know, a greater volume of air passes
through a vent stack because of greater draw when the cross-
sectional area o~ the verlt stack is larger and its height is
higher.
~evices, such as FranXel, in Canada have been
banned by the Canadian Standards Association precisely for
the reasons hereinbefore enumerated.
The present invention overcomes the major failing
of Frankel by having a time dependant or time elapse delay
3~
system immune from temperature and other factors, 50 that
the hea-~ing cycle ignition and de-ignition points are
precisely maintained. Also a synchronous motor is provided
for slowly moving the vent from its open to closed position.
The present invention therefore contemplates an
improvement to a heatlng system that includes a furnace for
generating heat, and that passes exhaust by-products up a
venting stack, the furnace having a furnace control circuit
to turn off and on the furnace, the improvement comprising:
(a) a damper having a pivoting vane in said
venting stack, the vane pivoting between an
opened and a closed position;
(b) an actutator attached to the pivoting vane
for pivoting said vane to the open and to the
closed positions, said actuator including;
(i) a synchronous motor coupled to a sha~t
and to said vane for pivoting said
vane;
(ii) a time dependant delay means including
first switch means for making
electrical connection with the motor
whereby to energize the motor into
rotation whereby the vane rotates;
(iii) second switch means for making
electrical contact and adapted to be
connected in series ~ith the furnace
control circuit and to energize the
furnace control circuit when the
second switch means is closed so as to
3~ cause the furnace to go on;
(iv) means carried by the shaft for closing
- 5
the second switch means when the shaft
is at a predetermined relative
position;
(v) relay means including first and second
contact pairs, the relay means
responsive to and adapted for serial
connection to a thermostat whereby on
closing of the thermostat, in response
to the minimum ambient temperature
selected, the relay means is energized
to open one of said contact pairs and
to close the other of said contact
~ !
pairs, the first said contact pair in
series with the motor whereby to
de-energize the motor whereupon the
vent rotates open and when fully open
means (iv) closes the switch means
I
.~ Il (iii) whereby the furnace control
~ circuit is closed and the furnace
~ turns on, the second of said contact
pairs being:in series withlsaid second
; switch means and the furnace control
circuit.
- ,
This~invention al90 contemplates an improved
method of pre~erving heat within an environment that
utilizes a furnace for generating heat, whether by gas or
oil fired b~rner, and that: passes.as exhaust, by-products,
up a vent~ng stack the furnace having a control circult
~ : which turns it off, the improved method including the steps
o~
(a) positioning, in the venting stack, in close
'
~ - 6
proximity ko the furnace a damper having an
operative pivot.ing vane therein for opening
and closing the cross-sectional area of the
damper and hence, the venting stack;
(b) operating the damper to close the venting
stack after a predetermined time when the
furnace is not consuming fuel to create heat;
(c) sensing the ambient temperature of an
environment to be heated and establishing
therefore, a maximum and minimum ambient
temperature;
(d) activating the damper to open when the
minimum ambient temperature is sensed by said
sensing step;
~e) igniting the combustionable fuels in said
furnace so that said furnace creates heat and
conveying the heat to said environment;
(f) closing the supplv of fuel to the urnace
when the maximum ambient temperature is
20 :~ reached; and
: (g) waiting a predetsrmined period, after step
e) and~then closi~ng the vent in the exhaust
flue~stack thereby preservlng the remaining
: heat contained ~ln~the furnace for distr:ibu-
tion to~the~env1ronment.
Ihe invention will. now be described by way of
example wi h reference to the accompanying drawings in
:
: which~
:, j :
~ Figure 1 i8 a perSpeCtlVe; vieW of the mechanical
30 ~ device.
: Figures 2 and 3 are side elevations respectively,
~ ~, .
of the device of Figure 1.
Figure 4 is a location diagram of the vent in use.
Figure 5 is a top view of a Eull closure ven-t
preferred for oil fired application, as is shown in side
elevations in Figures 2 and 3.
Figure 6 is a.n electrical ci.rcuit diagram.
Figure 7 ls an alternative embodiment of a damper,
top view as in Fiyure 2, but possessing a vane of reduced
area to show continuous venting in the closed position, as
preferred for gas fired application~
Referring, in part to all the drawings, the
principal embodiments of ~he invéntion as now preferably
, 1~
contemplated by th~ inventor include~ in surnmary, an
improved heating jsystem that includes a furnace, referred to
as referenice 30,~ for generating heat, whether as a gas fired
or oiljfired o~. otherwise fired unit, and that passes
exhaust bylproducts as a result of combustion up a venting
stack, refèrenced,l32. Th furnace has a furnace control
,
circuit (not shown), but those skilled in the art will be
famillar with it,;to turn~the furnace off and on; the
mprovement comprises,~a damper, generally illustrated as 1,
having a pivotlng;vane, eîther 15 or 15', in said venting
stack.2, the;vane~pivoting: between a closed (the solid
po~ition in ~igure~l) and;an open position tthe fanthom
position in Figure l); an acutator attached to the pivoting
vane for pivoting said vane to the open or to the closed
positions. The said actuator includes a synchronous motor 6
coupled to a sha~t 7'and to said vane 15 for pivoting said
vane; a time dependant delay means 9 including a first
switch means, 9'' for making electrical connection with the
motor 6 whereby to energize the motor 6 into rotation
. - 8
. .
whereby the vane 15 rotates. A second switch means
referenced 11 for making electrical contact and adapted to
be connected in series with the furnace control circuit and
to energize the furnace control clrcuit when the second
switch means is closed so as to cause the furnace to go on.
Means (the projection of lever arm 4) carried by the shaft 7
for closing the second switch means when the shaft 7 and
hence, lever 4 is in a predetermined position. A relay
means 19 includes first and second contact pairs as
illustrated, the relay means 19 responsive to and adapted
for serial connection to a thermostat, referenced 43,
whereby on closing of the thermostat, in response to the
minimum ambient temperature selected for the heated
environment, the relay means 9 is energi~ed to open one of
said contact pairs and to close the other of said contact
pairs, the first of said contact pairs connected in series
to the synchronous motor 6 whereby to de-energize the motor
whereupon the vent 15 rotates open under the force of a
biasing spring 14, and when fully open the projection of
shaft 4 closes the switch means 11, which in the preferred
embodiment is a micro-swi~ch. The furnace control circuit
i5 thus closed and the furnace 30 turns on, the second of
said contact~paixs being connected in series with said
~econd switch means 11 and the furnace control circui~.
Af er the thermostat reaches and senses the
maximum ambien~ temperature selected, it opens and this
opens the relay mean~ which reverses the two contact pairs
which, in one circuit, immediately opens the furnace control
circuit so that the furnace is turned off, and in the other
circuit energizes the time dependant dela~ means 9 whereupon
after the predetermined delay of time, the coil 9' thereof,
:
causes the switch 9'' to close activating the synchronous
motor 6 into the counter-clockwise direction to close the
vane 15.
Referring to Figures l and 4 a damper assembly 1
is positioned in the exhaust flue venting stream downstream
from a furnace or other heating device 30 to which it is
attached. More particularly, the damper l is positioned in
-the vent stack 32 just downstream of a barometric damper 33
that i5 disposed between furnace 30 and damper 1.
Referring to Figures 1 through 5 the damper
assembly 1 includes outer sheet metal tubing 2, preferably
of aluminized steel to resist rust and to withstand 1200F
(650C) and a diametrically positioned shaft 7 which
projects into outside bearing members 16 mounted in the
walls of the tubing 2. A circular sheet member 15 is
affixed to the shaft 7 as a vane and is pivoted by the
rotational position of the shaft whereby to open and close
the internal diameter and to change the effective cross
sectional area of the sleeve 2. One end of the damper shaft
7 extends to a coupling 8 which attaches itself, as by
conventional means, to a synchronous motor 6 that is secured
by bolts 6I through standoffs or spacers 6" onto a
circumferential housing 20. Through coupling 8 is mounted a
lever arm 4 which acts as a lever that can mechanically move
or pivot the vane 15 from open to closed or closed to open
position. 1~0 vane is shown in Figure 1, in fanthom, in a
more open position than in solid and the position of the
lever arm 4 in the fanthom position is that which
correspondingly represents the more open position ln
fanthom. A return coil spring 14 embraces the lever 4 and
biasingly urges the shaft 7 counterclockwise, when referring
- 10
electric synch~onous motor 6 i5 energized, it urges against
to Fîgure 2, so that the vane is fully opened. When the
the bias of the spring 14 to close the vane and to hold the
vane in -the closed position, that of Figure 5.
Referring to the electrical circuit diagram Figure
6 it includes a terminal block 35 for the interconnection of
various wires and circuits associated with the time delay
mechanism 9 the relay mechanism la housing first and second
contact pairs and other switches. Wire pair 40 is to be
connected to a 24 volt transformer which supplies the energy
to the complete system. Wire pair 42 interconnect to a room
thermostat 43 which, when closed, calls for heat. The heat
cycle commences. In reality the thermostat 43 eneryizes
relay 18 to make contacts of the first contact pair and
break the contacts of the second contact pair. Wire pair 41
is interconnected to the heating device 30 and for example
is connected directly to either a gas solenoid which
operates the gas valve of a gas fired furnace, or in the
case of an oil burner, to the electrical motor of the oil
~O burner of an oil fired furnace. Hence, this pair 41 is
connected to the furnace on/off control circuit. Access to
this circuit i9 obtained by disconnecting the boiler or
furnacé high limit control and placing this wire pair in
series therewith so that the boiler or furnace is activated
ON when the micro-switch 11 closes, From the terminals of
the terminal block 35, the wire pair 41 is in series with
the micro-switch 11 and with the second contact pair
(normally open) of relay 18. When relay 18 is energized
this second contact pair is closed.
Assuming, now, that the motor 6 is energiæed to
ho:Ld the vane 15 in the closed position of Figure 5, in that
instance, the time delay relay 9 will be closed a~ in the
solid position of Figure 1. When the room thermostat 43
closes and the call of heat therefore is made, control relay
18 is energized thereby and the contacts of relay 18 are
therefore moved from the solid to the fanthom position, of
both contact pairs. Contacts of the time delay 9 are opened
~rom the fanthom position to the solid position and the
motor 6 is de~energizedO On de-energization, the return
coil spring 14 moves the vane 15 to the open position, the
fanthom position of Figure 1 and when the open position is
fully achieved, (see Figure 3) the projection of the lever 4
through the shaft 7 strikes the leverage arm 49 of the
micro-switch 11 to close the same thereby completing the
furnace control circuit through the second contact pair of
relay 18. The furnace goes on and heating begins.
When the heat level required is reached, the
thermostat 43 opens thereby de-energizing the relay coil 18
moving the contact pairs thereof into the solid position
shown in Figure 6. The furnace goes off since the second
contact pair of relay 18 is opened thereby. The time delay
coil 9' is energized but will not activate the switch
thereof until the given time delay period of the time delay
switch is reached; typ1cally two minutes. When the time
delay period ha~ elapsed,~the switch 9'' closes and the
synchronous motor 6 is activated to return the vane 15 (15')
to the closed position. A typical time delay mechanism
preferred, is a~mechanical~time delay mechanism that is
preferably temper~ture compensated. That manufactured by
the Paragon Electric Company, a division of AMF of the
United States of America with a two minute delay, namely,
model number #903 mechanical time delay mechanism is
- 12
satisfactory.
For servicing or for other reasons where it is
desirable to override the electrical function of the vent as
hereinbefore described and hence to cause the vane 15 to be
located and fixed in the open position, the lever arm 4 may
be moved by hand from the solid position to the fan~hom
posi-tion, as shown in E`igure 1, and the dead bolt 50 indexed
-there to cross and to hold the lever arm 4 in the vertical
fanthom position. This mechanical override permits
maintainance of the device 1 and the furnace while at the
same time, since the longitudinal axis of the lever arrn is
mounted in the same plane as that of the vane 15, the lever
arm 4 is a visual indicator of the actual position of the
vane 15 in the damper 1.
In order to keep the actuator cornponent as "cool"
as possible and thereby to eliminate the transfer of heat
from the stack 2 to the hou~ing 20 and its cover 20' they
are mounted on an extension bracket 25 and if desirable, the
extention~bracket 25 may be composed of material other than
metal so that to inhibit, as much as possible, the
conductlon o~ heat from the sleeve to the housing 20 and its
components. Mounting of the bracket 25 to the stack 2 is
simplictica1ly done by sheet metal screws, shown in Figur~ 1
but not r~ferenced.
ReferrLng to Figure 5 and another embodiment of
vane 15' the ~ame has its~peripheral margins parallel and
truncated so that the vane~15' displays an area as when in
the closed position of Figure S of about 90% of the actual
cross sectional area of~the sleeve 2. This, leaves, on the
two diametrically oppo~ed marginal sides of the vane 15'
space area 19 for flue gases to pass by the vane 15' even
when i.n the fully closed position. This eature is
desirable when the damper assembly 1 is used in gas fired
furnaces, with pilot lights, so as to not inhibit the flow
of exhaust bi-products generated in the fire box by the
pilot light during furnace de-ignition.
,
,
- 14
,
