Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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D E S C R I P T I O N
HOT WATER BOILER SYSTEM
BAC~GROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hot water boiler
system for domestic use using oïl or gas as its fuel, and
more particularly to a hot water boiler system of the type
of an atmospheric operation (hereinafter, referred to as
an operation under no pressure), capable of controlling
automatically the pressure of hot water under atmospheric
pressure.
2. Description of the Prior Art
In general hot water boiler systems which conduct a
circulation of hot water to achieve both of room heating
and hot water supp~lying, water in a heating chamber
(namely, a heat exchanging chamber) disposed in a boiler
body is heated using fuel such as oil, gas or electric
power, as heat source. The water heated to high
- temperature is circulated to conduct room heating and
supplied as water for a bath or other purposes. These
boiler systems essentially require a room heating water
supplement device for supplementing a portion of room
heating water which is naturally lost during its
circulation due to certain causes, and an expansion device
for reducing the internal pressure of the heating chamber
increased due to an increase in the specific gravity of
room heating water which is caused by an increase in the
temperature of room heating water.
To this end, such conventional boiler systems
comprise a supplement water tank (so called, "expansion
tank") disposed outwardly of a boiler case and provided
with a ball float-controlled valve, as shown in FIGS. 7
and 8. The supplement water tank is connected to a room
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heating water feedback pipe via the ball float-controlled
valve and a supplement water pipe, so as to supplement the
- naturally lost hot water portion. In order to control the
internal pressure of the boiler, an expansion pipe
(namely, a relief pipe) is also provided which is
connected at one end thereof to an uppermost portion of a
room heating water output line and at the other end
thereof to the supplement water tank.
However, such a construction is restricted in its
installation, because o~ requiring a separate space in
which the supplement water tank occupies and a
considerable height for naturally generating a water head.
Moreover, foreign matters are likely to enter the
supplement water tank and cause clogging of the supplement
water pipe due to their deposition. Frequent failures of
the ball float-controlled valve which controls the water
level in the supplement water tank also may result in a
submergence of the boiler chamber, a fatal failure or
damage of the boiler operation system equipped with
electronic appliances, a precise motor and etc...... The
conventional boiler system also has a trouble in use, in
that air generated from oxygen dissolved in water for
several months after the installation of boiler-should be
-periodically vented out of the boiler. -
On the other hand, the conventional boiler system
includes an operation system e~uipped with a control
- device for automatically controlling the operation of
boiler system. However, this control device has simple
~unctions insufficient to provide a perfect automatic
control of the overall operations of boiler system.
~urthermore, it has no utility and thereby can not meet
the demand of users.
That is, the functions of control device are mainly
carried out by ON/OFF switchings. In response to pushing
of an operation ON button, the control device makes the
boiler system carry out its room heating operation, by
activating the fuel supply device, operating a burner to
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burn fuel supplied from the fuel supply device and thus
heat water in the water chamber, and activating a
circulation pump P to circulate hot water in the water
chamber via a room heating water circulating line. In
response to pushing of an operation OFF button, the
control device shuts off supplying of the fuel, thereby
stopping the room heating operation of the boiler system.
With such a control device, room heating temperature
can be controlled only by repeating manual ON/OFF
switchings of the operation of boiler. As a result, there
are disadvantages of inconvenience in .use, inefficient
room heating, and wastes of fuel and electric power.
In the conventional boiler system, furthermore, the
driving of the circulation pump P is performed only-when
the boiler system operates in its room heating mode, in
other words, a room heating system of the boiler system
operates. Since such a room heating system is generally
not operated for a long time in the summer season, a motor
bearing unit which is a driving part of the circulation
motor is apt to rust after the rainy season is over.
Impeller of the motor also tends to be subjected to a
fixing phenomenon caused by an accumulation of foreign
matters (generated due to a thermal deformation of the
impeller) thereon. If, as the autumn season sets in, the
room heating system is operated without any maintenance,
the motor is subjected to a failure. Moreover, such an
operation may causes a fire.
S UMMARY OF THE I NVE NT I ON
Therefore, an object of the invention is to provide
a hot water boilçr system wherein a supplement water tank
of the type open to atmosphere is disposed in a boiler
case, capable of achieving convenience and safety in its
installation and automatic supplement and expansion of
room heating water.
Another object of the invention is to provide a hot
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water boiler system wherein a room heating water
supplement line equipped with an electromagnetic valve is
connected to a hot water supply line and a sensor is
provided in a water supplement tank to sense a low water
level so that automatic room heating water supplement is
achieved by opening and closing operations of the
electromagnetic valve according to the sensing operation
of the sensor.
Another object of the inve~tion is to provide a hot
water boiler system wherein an overheat safety switch is
disposed and exposed outwardly of a boil'er case, capable
of facilitating convenience in use, achieving automatic
water supplying upon a shortage of room heating water in
a water chamber, and achieving periodical temporary
operation of a circulation pump in the summer season that
a room heating system is not operated for a long time so
that the circulation pump can be always ready for its
~ormal operation.
In one aspect, the present invention provides a hot
water boiler system having a room heating function and a
hot water supply function comprising: a boiler; a boiler
case enclosing said boiler; a heat exchanging chamber
formed in the boiler and having a water chamber in which
hot water to be used as room heating water is contained;
a circulation pump for circulating said room heating water
along a room heating circulation path; a hot water supply
device having a cold water input line and hot water output
line; a supplement water tank, of the type open to
atmosphere, disposed in said boiler case and communicated
with said heat exchanging chamber, said supplement water
tank having means for automatically performing an
expansion and supplement of room heating water required,
due to a variation in density of said room heating water
contained in said water chamber, to release an excessive
pressure generated in the water chamber; a supplement
water line connected at one end thereof to said cold water
input line of the hot water supply device and at the other
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end to the supplement water tank, said supplement water
line having a water supply valve adapted to allow water to
flow from the cold water input line to the supplement
water line, upon opening thereof; and control means for
controlling said water supply valve to open it when water
level in the supplement water tank reaches a predetermined
low water level, said control means having a low water
level sensor for sensing the predetermined Low water
level.
In another aspect, the present invention provldes a
control device for controlling the operation of a.boiler
system which comprises a boiler equipped with a burner
device having a burner motor, an ignition transformer and
an oil pump, a heat exchanging chamber formed in the
boiler and having a water chamber in which hot water to be
used as room heating water is contained, a circulation
pump for circulating said room heating water along a room
heating circulation path, an expansion tank for
supplementing water in said water chamber, and a water
supply valve connecting said expansion tank to an external
water supply source, said control device comprising:
control means for receiving signals from peripheral
equipments, discriminating these signals and outputting
drive signals to corresponding boiler system drive units,
that is, said burner motor, said ignition transformer,
said oil motor, said circulation pump and said water
supply valve; a room temperature controller; room signal
receiving means for receiving a drive signal from a room
temperature controller and outputting a converted signal
based on the received drive signal to said control means;
output means for receiving output signals from the control
means and controlling supplying of electric power to said
boiler system drive units, based on the received signals;
a temperature sensor for the temperature of room heating
water contained in the water chamber; temperature display
means for receiving a signal from said temperature sensor
and displaying the temperature of room heating water based
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on the received signal; an overheat sensor for sensing an
overheat of the room heating water; overheat sensing means
for receiving a signal representative of the sensed
temperature from said overheat sensor, comparing the room
heating water temperature with a reference temperature and
outputting a safety shutoff signal to the control means
when an overheat i5 sensed according to the comparison; a
flame sensor for sensing burning flame in the boiler;
safety shutoff means for receiving a non-flame signal from
said flame sensor and outputting a safety shutoff signal
upon receiving the non-flame signal; a,low water level
sensor for sensing a predetermined low water level in the
expansion tank; low water level sensing means for
receiving a signal from said low water level sensor and
outputting a low water level signal to the control means
upon detecting a water shortage, based on the received
signal, and simultaneously outputting a water supply
signal to said output means; an oil quantity sensor for
sensing the quantity of remaining oil; oil quantity
sensing means for receiving a signal from ~aid oil
quantity sensor and detect the quantity of oil, based on
the received signal; alarming means for alarming abnormal
operations of the boiler; and anti-fixing means for making
a temporary operation of the circulation pump during the
operation of the boiler system in a hot water supply mode,
to avoid an occurrence of fixing at the circulation pump.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and aspects of the invention will
become apparent from the following description of
embodiments with reference to the accompanying drawings in
which:
FIG. 1 is a schematic view illustrating an overall
construction of a ground installation type oil boiler
system in accordance with an embodiment of the present
nvention;
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FIG. 2 is a schematic view illustrating a wall hung
gas boiler system in accordance with another embodiment;
FIG. 3 is a schematic view of an automatic internal
pressure control device in accordance with the present
invention;
FIG. 4 is a schematic view of an automatic room
heating water supplement device in accordance with the
present invention;
FIG. 5 is a schematic view illustrating a connection
between the devices shown in FIGS. 3 and 4;
FIG. 6 is a schematic view of a'connection of a
circulation pump according to other embodiment of the
present invention;
FIG. 7 is a schematic view illustrating an overall
construction of a conventional boiler system;
FIG. 8 is a schematic view of a conventional room
heating water supplement device;
FIG. 9 is a block diagram of a control device for a
boiler system in accordance with the present invention;
FIG. 10 is a circuit diagram of a control unit of the
control device according to the present invention;
FIG. 11 is a circuit diagram of an output unit and a
safety shutoff unit of the control device according to the
-present invention;
FIG. 12 is a circuit diagram of a forcible water
supply circuit in accordance with-the present invention;
- FIG. 13 is a circuit diagram of an overheat sensing
circuit in accordance with an embodiment of the present
invention;.
FIG. 14 is a circuit diagram of an overheat sensing
circuit in accordance-with another embodiment of the
present invention;
FIG. 15 is a circuit diagram of a low water level
sensing circuit in accordance with the present invention;
. FIG. 16 is a circuit diagram of a circulation pump
control circuit in accordance with an embodiment.of the
present invention; and
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FIG. 17 is a circuit diagram of a circulation pump
control circuit in accordance with another embodiment of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. l, there is illustrated a hot water
boiler system having various functions such as room
heating, hot water supplying and operation controlling in
sleeping and outing, in accordance with an embodiment of
the present invention. The boiler mainl~ comprises a heat
exchanging chamber 2, a burner device 3, a water
supplement tank 4, a circulation pump 5, a hot water
supply device 6, a fuel supply device, a room heating
water supplement device 7 (FIG. 7), and a control device (namely,
an ~ation controllmg device) 10 (FIG. 3) for automatically
controlling the operation of a boiler.
The heat exchanging chamber 2 includes a -ire
chamber, a burning chamber, a water chamber 21 (FIG. 3),
and a flue 22.
The hot water supply device 6 includes a hot water
supply coil 61 (FIG. 4) disposed in the water chamber 21
of heat exchanging chamber 2, cold water input line 62 and
hot water output line 63 (FIG. 1).
The burner device 3 includes a burner motor 31, a
combustion gas suction pipe 32, an ignition transformer
and a diffuser.
In accordance with the present invention, the water
supplement tank (expansion tank) 4 is disposed in a boiler
case 1 and shaped into a box. As shown in FIG. 3, the
water supplement tank 4 has at its upper portion a port 41
which makes the water supplement tank 4 open to the
atmosphere. Accordingly, the water supplement tank 4 is
the type open to the atmosphere. The water supplement
tank 4 is communicated with the water chamber 21, via an
expansion pipe 42, as shown in FIG. 3. The expansion pipe
42 has one end deeply inserted into the interior of water
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supplement tank 4 and the other end connected to a socket
23 mounted to the upper portion o~ water chamber 21. In
accordance with an embodiment of the present invention,
the expansion pipe 42 is a syphon pipe. At the lower
portion of water supplement tank 4, a low water level
sensor S4 iS disposed to sense a predetermined low water
level in the water supplement tank 4. The low water level
sensor S4 iS connected to the control device 10
controlling the operation of boiler system according to
the present invention.
As shown in FIGS. 1 and 4~ the ro,om heating water
supplement device 7 includes a supplement water line 71
connected at its one end to the cold water input line 62
of hot water supply device 6, and a water supply valve 72
disposed in the supplement water line 71 and operated
under the control of control device 10. The other end of
the supplement water line 71 is connected to the water
chamber 21, by means of a socket 24 mounted to the water
chamber 21. In the socket 24, a temperature sensor S1 is
provided which checks the temperature of room heating
water in the water chamber 21, although not shown.
The circulation pump 5 serves to forcibly circulate
very hot water, as room heating water, in the water
chamber through a load 100 to be heated. As shown in ~IG.
1, the circulation pump 5 is installed on the bottom of
the boiler and disposed at a room heating water feedback
line 101 which is connected to the water chamber 21. With
this construction, cooled feedback water in the room
heating water feedback line lO1 is fed to the lower
portion of water chamber 21, by the circulation pump 5.
- In some cases, the circulation pump 5 may be disposed at
a room heating water output line 102, as shown in FIG. 6.
The control device 1~ includes a control panel
exposed outwardly o~ the boiler case 1. As shown in FIG.
9, the control device 10 mainly comprises a control unit
12 for receiving signals from peripheral e~uipments~
discriminating these signals and outputting control
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signals to corresponding units such as the burner device,
the circulation pump and etc., a room signal receiving
unit 11 for receiving a drive signal from a room
temperature controller (not shown) and outputting a
converted signal based on the received drive signal to the
control unit 12, and an output unit 13 for receiving
output signals from the control unit 12 and controlling
supplying of electric power to the burner motor 31 and the
ignition transformer of the burner device 3, the
circulation pump 5, an electromagnetic oil pump and the
- - water supply valve, based on the received signals. The
control device 10 also comprises a temperature display
unit 14 for displaying the temperature of hot water,
namely, room heating water, contained in the water chamber
21, an overheat sensing unit 16 for receiving a signal
representative of the room heating water temperature from
an overheat sensor S2, comparing the room heating water
temperature with a reference temperature and outputting a
safety shutoff signal to the control unit 12 when an
overheat is sensed according to the comparison, a safety
shutoff unit 17 for receiving a non-flame signal from a
- flame sensor S5 sensing burning flames in the boiler and
outputting a safety shutoff signal upon receiving the non-
flame signal, a low water level sensing unit 18 for
receiving a signal from the low water level sensor S4 and
outputting a low water level signal to the control unit 12
upon sensing a water shortage, based on the received
signal, and simultaneously outputting a water supply valve
opening signal to the output unit 13, an oil quantity
sensing unit having an oil quantity sensor S3 and sensing
the quantity of remaining oil, and an alarming unit for
alarming abnormal operations of the boiler.
In accordance with the present invention, there is
also provided an anti-fixing circuit 15 which serves to
avoid an occurrence of fixing at the circulation pump 5~
This anti-~ixing circuit 15 is incorporated in the control
unit 12 and comprises a sensing circuit 15A and a
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circulation pump controlling circuit 15B connected to the
sensing circuit lSA via a diode D42, as shown in FIG. 16.
The sensing circuit 15A is connected to the temperature
sensor S1 and includes a pair of series connected
comparators Q1 and Q2. The comparator Q1 is connected at
its non-inverting input terminal (+) to the temperature
sensor S1 and connected at its inverting input terminal (-
) to a tap on a voltage divider including resistors
and R~2 coupled between a voltage source Vcc and ground.
The output o-f comparator Q2 is fed back to the inverting
input terminal (-). The circulation 'pump controlling
circuit 15B includes a comparator Q3 coupled at its input
terminals to the voltage source Vcc, a charge circuit
constituted by a grounded resistor R86 and a condenser C21,
and another comparator Q4. The comparator Q3 is connected
at its non-inverting input terminal (+~ to a voltage
bypass resistor R84 and at its inverting input terminal (-
) to a tap on a voltage divider including resistors ~0
and Rg2 coupled between the voltage source Vcc and ground.
To the output terminal of comparator Q3 are connected the
condenser C21, resistors E~8s and R86, a diode D43, in this
order. The output terminal of comparator Q3 iS coupled to
the non-inverting input terminal (+) of comparator Q4 by
a diode D43 and grounded via a resistor R88. The
comparator Q4 iS connected at its inverting input terminal
(-) to a tap on a voltage divider including resistors R
and R87 coupled between the voltage source Vcc and ground.
The comparator Q4 iS also connected at its output terminal
to a circulation pump drive terminal CP of the output uni~
13, via a diode D44 and a resistor R89. The diode D42 is
connected between the junction of the output terminal and
inverting input terminal (-) of comparator Q2 and the
junction of the resistor R84 coupled to the voltage source
Vcc and the non-inverting input terminal (+) of comparator
Q3-
As shown in FIG. lO, the control unit 12 of the
control device lO is connected at its input with a decoder
-1~'
~ 21 0971 9
-12-
IC1 constituting the room signal receiving unit 11 and
equipped with the anti-fixing circuit 15 which is coupled
to a water supply signal output terminal b of the decoder
IC1. This control unit 12 mainly comprises four
comparators IC4, ICs, IC6 and IC7 and two inverters IC2 and
IC3. The comparator IC4 is connected at its non-inverting
input terminal (+) to a room heating signal output
terminal a of the decoder IC1, via a diode D7 and
resistors R3 and R10. To the room heating signal output
10 . terminal a of the decoder IC1, the comparator ICs is
connected at its non-inverting input term'inal (+), via the
resistors R12, R7 and R3 and diode D1. The inverting input
terminal (-) of comparator IC4 is connected, via a
resistor R11, to a tap on a voltage divider including
resistors Rs and R8 coupled between the voltage source Vcc
and ground, to the temperature sensor S1 and to the anti-
fixing circuit 15. In similar, the inverting input
terminal (-) of comparator ICs is connected, via a
resistor ~3, to the tap on a voltage divider including
resistors Rs and R8 coupled between the voltage source Vcc
and ground, the temperature sensor S1 and the anti-fixing
circuit 15. The comparator IC4 is also connected at its
output terminal to both the overheat sensing un'it 16 and
the output unit 13, via a resistor R20 and a diode D7. The
2~ output terminal of comparator IC4 is also coupled by the
resistor R20 to the collector of a transistor TR3 which is
coupled at its base to the low water level sensing unit 18
by a resistor R21. The transistor TR3 is also coupled at
its emitter to ground and at its base to the water supply
signal output terminal b of the decoder IC1, by diodes D2
and D4 and the resistor R21. On the o~her hand, the
comparator ICs is also connected at its output terminal to
the inverting input terminal of comparator IC7, via
resistors R23 and R30. The comparator IC6 is connected at
its non-inverting input terminal (+)/ via a resistor R27,
to a tap on a voltage divider including resistors R2s and
R31 coupled between the voltage source Vcc and ground. In
.;.
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... .
-13-
similar, the comparator IC7 is connected at its non-
inverting input terminal (+), via a resistor R29, to a tap
on a voltage divider including resistors R25 and R31
coupled between the voltage source Vcc and ground. The
comparator IC6 is coupled at its inverting input terminal
(-) to the output terminal of comparator IC7 and at its
output terminal to the safety shutoff unit 17. The
comparator IC7 is connected at its inverting input
terminal (-) to the output terminal of comparator IC5, via
resistors R23 and R30. The output terminal of comparator
IC7 is coupled to the output unit 13 by a resistor R32.
The inverter IC2 is coupled at its input terminal to an
outing signal output terminal d of the decoder IC1 and at
its output terminal to the base of a transistor TR2 by a
resistor R4. The collector of transistor TR2 is coupled
to an output terminal c of the decoder IC1. The inverter
IC3 is connected at its input terminal to the output
terminal c of the decoder IC1 and at its output terminal
- to the base of a transistor TR4, via a resistor R18. The
transistor TR4 is coupled at its collector to a
temperature control volume V~ and at its emitter to
ground. The temperature control volume V~ is coupled at
one side thereof to the voltage source Vcc by 'resistors
-R6, R7, ~4 and R15 and at the other side thereof to ground.
A transistor TR5 is also connected at its base to both the
output terminals c and d of decoder IC1 and at its emitter
to ground.
As shown in FIG. 11, the output unit 13 comprises a
burner motor drive circuit BMD1, an ignition transformer
drive circuit ITD2, an oil pump drive circuit EPD3, a
circulation pump drive circuit CPD4, and a water supply-
valve drive circuit AWD5. The burner motor drive cir-cuit
BMD1 has an input terminal BM coupled to both the
inverting input terminal (-) of the comparator IC6 of
control unit 12 and the output terminal of comparator IC7.
The burner motor drive circuit BMD1 also has a transistor
T~ coupled at its base to the input terminal BM and a
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-14-
relay RY1 coupled to the collector of transistor TR9. The
input terminal IT of ignition transformer drive circuit
- ITD2 and the input terminal EP of oil pump drive circuit
EPD3 are coupled to a timer IC1o o~ a timer circuit l9.
The ignition transformer drive circuit ITD2 has a
transistor TRlo coupled at its base to the input terminal
IT and a relay RY2 coupled to the collector of transistor
TR1o. In similar, the oil pump drive circuit EPD3 has a
transistor TR11 coupled at its base to the input terminal
EP and a relay RY3 coupled to the collector of transistor
TR11. The circulation pump drive circuit'CPD4 has an input
terminal CP which is coupled to the output terminal of the
comparator IC4 of control unit 12, the output terminal of
the comparator Q4 of anti-fixing circuit 15 and a forcible
water supply button MWB. The circulation pump drive
circuit CPD4 also has a transistor T~2 coupled at its base
to the input terminal CP and a relay RY4 coupled to the
collector of transistor TR12. On the other hand, the
water supply valve drive circuit AWD5 has an input
terminal AW coupled to the output terminal of a comparator
IC18 of the low water level sensing unit 18. The water
supply valve drive circuit AWD5 also has a transistor TR13
coupled at its base to the input terminal AW and a relay
- RY5 coupled to the collector of transistor TR13.
The forcible water supply button MWB is one of
constituting elements of a forcible water supply circuit
which is incorporated in the control device 10 in
accordance with the present invention. In addition to the
forcible water supply button MWB, the forcible water
supply circuit comprises a pair of light emission diodes
LED3 and LE~4, as shown in F~G. 12. The Button MWB is
coupled at one side thereof to the source voltage Vcc by
a resistor R66 and at the other side thereof to both the
input terminal CP of circulation pump drive circuit CPD4
by a diode D29 and the light emission diodes LED3 by a
resistor R65. The other side of button MBW is also
- connected to both the input terminal AW of water supply
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va~ve drive circuit AWD5 via a diode D30 and the light
emission diodes LED4 by a resistor R67.
The overheat sensing unit 16 comprises a pair of
series connected comparators IC16 and IC1~ and the overheat
sensor S2, as shown in FIG. 13. The comparator IC16 is
connected at its inverting input terminal (-) to the
overheat sensor S2 and connected at its non-inverting
input terminal (+) to a tap on a voltage divider including
resistors R69 and R70 coupled between the voltage source
Vcc and ground. The comparator IC17 is connected at its
non-inverting input terminal (+) to the o~tput terminal of
comparator IC16, via a diode D31 and a resistor R71. The
inverting input terminal (-) of comparator IC17 is
connected to a tap on a voltage divider including
resistors R73 and R75 coupled between the voltage source
Vcc and ground. Between the input terminals of comparator
IC17, a condenser C10 is connected. The output terminal of
comparator IC17 is coupled to the inverting input terminal
(-) of the comparator IC7 of control unit 12 by diodes D35
and D3~ and to the collector of transistor TR5 of control
unit 12. At the junction between the resistor R71 and the
condenser C10, a manual operation return switch or button
RSW is coupled by a diode D32. The manual operation
-return button RSW is provided at the control panel of
control device 10 which is mounted to a front door of
boiler case 1 such that it exposes outwardly.
As shown in FIG. ll, the safety shutoff unit 17
comprises a pair of series connected inverters IC13 and
IC14, a comparator IC15 and the flame sensor S5. The input
terminal of inverter IC13 is coupled to the voltage source
Vcc by a resistor R38. To the junction between the
- resistor R38 and the input of inverter IC13 is coupled the
flame sensor S5 by a diode D14. The output terminal of
inverter IC13 is directly coupled to the inverter IC14. To
the output terminal of inverter IC14, a transistor TR6 is
coupled at its base by a resistor R46. The output
terminal of inverter IC14 is also connected to the input
~ 16- 2109719
terminal of an inverter IC12 which is one of constituting
elements of the timer circuit 19. To the output terminal
of inverter IC14, a transistor TR7 is also connected at its
base, via a diode D20 and resistors R50 and R51. The
emitter of transistor TR6 is coupled t~ the timer IC1o. To
the transistor TR7, a transistor TR8 is series connected~
The transistor TR8 is coupled at its base to the output
terminal of timer IC10, by a resistor R49 and a diode D19.
The transistor TR8 is also connected at its collector to
the inverting input terminal (-) of comparator IC15 and at
its base to ground via a resistor R53.~ The inverting
input terminal (-~ of comparator IC15 is connected to a
tap on a voltage divider including resistors ~4 and R58
coupled between the voltage source Vcc and ground. The
comparator IC15 is also connected at its non-inverting
input terminal (+), via a resistor R56, to a tap on a
voltage divider including resistors R55 and R59 coupled
between the voltage source Vcc and ground. The output
terminal of comparator IC15 is coupled to a light emission
diode LED2 by a resistor R65 and to the inverting input
terminal (-) of the comparator IC7 of control unit 12.
The output terminal of comparator IC15 is also coupled to
the alarming unit. To the junction between the resistor
-R56 and the non-inverting input terminal (+) of comparator
IC15 is coupled the manual operation return switch or
button RSW, by a resistor R60 and a diode D22. The button
RSW is also coupled to the control unit 12 by a diode D12.
The safety shutoff unit 17 also comprises a diode D28
which is coupled at its one side to the output terminal of
the comparator IC6 of control unit 12. The other side of
diode D28 is coupled to the timer IC1o.
The low water le~el sensing unit 18 comprises the
comparator IC18 and the low water level sensor S4, as shown
in FIG. 15. The low water level sensor S4 is coupled to
the inverting input terminal (-) of comparator IC18, by a
bridge rectifier circuit BD and a resistor R71. The non-
inverting input terminal (+) of comparator IC18 is
7~1 9
~_ -17-
connected to the voltage source Vcc. The output terminal
of comparator IC18 is coupled to the resistor 21 of control
unit 12 by a diode D37, to the input terminal AW of water
supply valve drive circuit AWD5 by a diode ~36 and to both
the inverting input terminal (-) of the comparator IC7 of
control unit 12 and the alarming unit by a diode D38.
The operation of the control device mentioned above
will now be described.
As user pushes a room heating switch of the room
temperature controller positioned in a room or hall, a
room heating signal is generated and~applied to the
control device 10. That is, the room heating signal is
applied to the room signal receiving unit 11 equipped in
the control device 10. In the room signal receiving unit
11, the decoder IC1 converts the room heating signal into
a voltage pulse signal waveform-shaped to be recognizable
by the control unit 12 and then sends it to the control
unit 12.
The voltage pulse signal is outputted at the room
heating signal output terminal a of the decoder ICl and
thus applied to the non-inverting input terminal (+) of
comparator IC4 via the diode D1 and resistors R3 and R10.
Accordingly, the comparator IC4 generates a high level
output signal which is, in turn, sent to the input
terminal CP of the circulation pump drive circuit CPD4 of
output unit 13, via the resistor R20 and the diode D7. In
the circulation pump drive circuit CPD4, the transistor
T~2 is activated by the signal received at its base,
thereby causing the relay RY4 to be activated. By the
activation of relay RY4, AC power is supplied to the
circulation pump 5 disposed in the boiler case 1, thereby
enabling the circulation pump 5 to drive. On the other
hand, the signal from the room heating signal output
terminal a of the decoder IC1 is also applied to the non-
inverting input terminal ~+) of comparator IC5, via
resistors R7 and ~2' The comparator IC5 also receives the
source voltage Vcc at its inverting input terminal (-) via
-18- 2109719
resistors R5 and R13, in that the temperature sensor S1 is
at its OFF state. Since the voltage level at the
inverting input terminal (-) of comparator IC5 is higher
than that at the non-inverting input terminal (+), the
comparator ICs outputs a low level signal, so that the
comparator IC7 which receives at its inverting input
terminal (-) the low level output from the comparator IC5
via resistors R23 and R30 outputs a high level signal. At
this time, the temperature sensor 51 is at its OFF state.
This high level signal from the comparator IC7 is sent to
the input terminal BM of the burner motor drive circuit
BMD1 of output unit 13. In the burner motor drive circuit
BMD1J the transistor TRg is activated by the signal
received at its base, thereby causing the relay RY1 to be
- 15 activated. According to the activation of relay RY1, the
burner motor 31 of burner device 3 drives. ~y the driving
of burner motor 31, combustion air enters the diffuser via
the combustion air suction pipe 32. At the same time, the
comparator IC6 outputs a high level signal which is, in
turn, sent to the timer IC10 of timer circuit 19 via the
diode D28 of safety shutoff unit 17. In response to the
signal from the comparator IC6, the timer IC10 applies an
output signal to the input terminal EP of the oil pump
-drive circuit EPD3 of output unit 13. In the oil pump
drive circuit EPD3, the transistor TRl1 is activated by the
signal received at its base, thereby causing the relay RY3
to be activated. According to the activation of relay
RY3, the electromagnetic pump which is a fuel ~supply
device drives and supplies oil to the burner device 3.
After the lapse of a predetermined time, the timer IC10
applies an output signal to the input terminal IT of the
- ignition transformer drive circuit ITD2. In the ignition
transformer drive circuit ITD2, the transistor TR10 is
activated by the signal received at its base, thereby
causing the relay RY2 to be activated. By the activation
of relay RY2, power is supplied to the ignition
transformer, thereby achieving an ignition and thus
-19- 21097 19
combustion of oil. By continued combustion of oil, water
in the water chamber 21 is heated, thereby carrying out
- room heating. That is, by the forcible pumping operation
of circulation pump 5, hot water in the water chamber 21
as room heating water is repeatedly circulated along a
room heating water circulation path constituted by the
room heatlng water output line 102, the load 100 arranged
around the room and room heating water feedback line 101,
so as to achieve room heating.
When the temperature of room heating water in the
water chamber 21 increases above the temperature set by
the temperature control volume ~ (FIG. 10) during the
room heating operation, the temperature sensor S1 which is
a thermistor is activated, thereby causing the voltage
source Vcc to be coupled to ground via the resistor R5 and
the temperature sensor S1. As a result, a low level
signal is applied to the inverting input terminal (-) of
comparator IC5, so that the comparator IC5 outputs a high
level signal. As the high level signal from the
comparator IC5 is applied to the inverting input terminal
(-) of comparator IC7 via resistors R~ and R30, the
comparator IC7 applies a low level output signal to the
burner motor drive circuit BMD1, so that the transistor
-T~ is deactivated, thereby causing the relay RY1 for
driving the burner motor to be switched to its OFF state.
At the same time, in response to a high level signal from
the comparator IC6, the timer IC10 applies a low level
output signal to the oil pump drive circuit EPD3.
Accordingly, the transistor TR11 is deactivated, thereby
causing the relay RY3 for driving the electromagnetic oil
pump to be switched to its OFF state. As a result, the
temperature of room heating water increases no longer.
When the temperature of room heating water decreases below
a predetermined temperature, the burner and the oil pump
are operated again, to increase the temperature of room
heating water. Thus, the temperature of room heating
water can be maintained at a desired level, by repeating
-20-
the above-mentioned operations.
During the room heating operation of boiler, the
water in the water chamber 21 should be maintained at the
level needed for its room heating circulation. Also, the
internal pressure of water chamber 21 which may be
increased due to overheating of the heat exchanging
chamber 2 should be maintained at a proper level. To this
end, the present invention provides the supplement water
tank 4 disposed in the boiler case 1 and communicated with
the water chamber 21 via the expansion pipe 42, and the
supplement water line 71 constituting the room heating
water supplement device 7 connected to the water chamber
21 (conventionally, a supplement water tank disposed
outwardly of boiler is provided for the same purposes).
That is, as the pressure of room heating water
in the water chamber 21
increases due to continues heating, the increment of the
water pressure, that is, the excessive water pressure is
released to the supplement water tank 4 of the type of
open to atmosphere disposed in the boiler case 1, via the
internal pressure controlling socket 23 provided at the
upper portion of water chamber 21 and the expansion pipe
42 connected between the socket 23 and the supplement
water tank 4. Accordingly, the internal pressure of water
chamber 21 is automatically controlled and maintained at
a proper level. If the pressure of water is decreased
caused by lowering of
the water temperature of boiler, the quantity of water
which was discharged into the supplement water tank 4
during the expansion of water in the water chamber 21 is
fed back from the supplement water tank 4 to the water
chamber 21, via the expansion pipe 42. Therefore,
supplement of water from external is unnecessary. Air
bubbles which are generated during the above-mentioned
operations also vent automatically to atmosphere, through
the port 41 of supplement tank 41. Inconvenience of
periodically venting air as in prior art is naturally
-21- 2109719
eliminated. That is, water expansion and supplement
operations are automatically achieved under no pressure.
On the other hand, when the room heating water in the
water chamber 21 decreases in quantity, due to its
evaporation or leakage, its decreased quantity is
supplemented from the supplement water tank 4. If water
in the supplement water tank 4 is decreased below a
predetermined low water level by its supplement to the
water chamber 21, this is sensed by the low water level
sensor S4 which, in turn, makes the water supply valve 72
disposed in the supplement water line ~1 open under the
control of control device 10. Accordingly, the water
passing through the cold water input line 62 enters the
water chamber 21 through the water supply valve 72, so
that the water chamber 21 is filled again with the water
to a proper level. The supplement of water is continued
until the water level in the water chamber 21 reaches a
predetermined water level higher than the predetermined
low water level. That is, when the water level in the
water chamber 21 reaches the predetermined water level,
the water supply valve 72 is closed, thereby completing
the supplement of room heating water. Simultaneously with
the low water level sensing of low water level sensor S4,
- the heating operation of boiler is automatically stopped.
Therefore, the above-mentioned supplement of water is
- carried out under non-operation of boiler.
Now, this room heating water supplement operation
will be described, in conjunction with the control
circuits of the present invention.
When the low water level sensor S4 senses a shortage
of room heating water, it disables supplying of voltage
through the bridge rectifier circuit BD to the comparator
IC18 of low water level sensing unit 18 shown in FIG. 15.
As a result, the comparator IC18 maintains LOW level at
its inverting input terminal (-) and thus outputs a high
level signal. This high level signal from the comparator
IC18 is applied to the resistor R21 of control unit 12 via
210g719
-22-
the diode D37, thereby causing the transistor TR3 to be
activated. By the activation of transistor TR3, the
output terminal of comparator IC4 is coupled to ground.
Thereby, supplying of voltage to the circulation pump
drive circuit CPD4 of output unit 13 is shut off, and thus
the operation of circulation pump 5 is stopped. At the
same time, the high level signal from the comparator IC18
is applied to the alarming unit via the diode D38, so that
the room temperature controller displays alarm. The
output signal from the comparator IC18 is also applied to
the inverting input terminal (-) of compa~rator IC7 via the
diode D38 and the diode D39 of overheat sensing unit 16,
thereby causing the comparator IC7 to output a low level
signal. As a result, the operations of burner device 3
and oil pump constituting the fuel supply device are
stopped. The output signal from the comparator IC18 is
also applied to the input terminal AW of the water supply
valve drive circuit AWD5 of output unit 13, via the diode
D~. In the water supply drive circuit AWD5, the
transistor T~3 is activated by the signal received at its
base, thereby causing the relay RY5 to be activated. By
the activation of relay RY5, the water supply valve 72 is
opened to supply water to the water chamber 21.-
When the water level in the water chamber 21 reaches
a predetermined water level higher than the predetermined
low water level, the low water level sensor S4 enables
supplying of voltage through the bridge rectifier circuit
BD to the comparator IC18 so that the comparator IC18
outputs a low level signal. Accordingly, the alarm
displaying is stopped and the boiler is ready for its
normal operation.
As apparent from the above description, the low water
level sensing system of the present invention makes it
possible to automatically supplement water to the water
chamber without any troublesome manipulation, upon sensing
a shortage of water. Therefore, there is provided a
convenience in manipulation.
-23- 21097 19
On the other hand, when the temperature of room
heating water increases excessively and reaches a
dangerous level, due to the operation of boiler at a high
temperature for a long time or hot water supplying for a
long time, the overheat sensing unit 16 sends a safety
shutoff signal to the control unit 12, so as to stop the
operation of boiler.
This operation will now be described, in conjunction
with the circuit of overheat sensing unit 16 shown in FIG.
13.
When overheat occurs during the operation of boiler,
it is sensed by the overheat sensor S2 which is disposed
in the heat exchanging chamber 2 and integrated with the
temperature sensor S1. Accordingly, the comparator IC16
which is coupled at its inverting input terminal ~-) to
the overheat sensor S2 outputs a low level signal which
is, in turn, sent to the non-inverting input terminal (+)
of comparator IC17, via the diode D31, resistor R71 and
condenser C10. Thus, the comparator IC1? outputs a high
level signal which is a safety shutoff signal. This
signal from the comparator IC17 is applied to the
inverting input terminal (-) of the comparator IC7 of
control unit 12 via the diodes D35 and D39, so'that the
-comparator IC7 outputs a low level signal. Since the
comparator IC7 can not send a high level signal, the
operation of boiler is stopped, thereby achieving a safety
shutoff against the overheat. The output signal from the
comparator IC17 is also sent to the alarming unit via the
diode ~35, so that the alarming unit displays an alarm for
informing the user of the overheat.
Alternatively, the overheat sensing unit 16 may be
constructed by using a single comparator IC17, as shown in
FIG. 14. In this case, it is possible to obtain a simple
and inexpensive construction, although the sensitivity is
degraded.
Return of the normal operation of control device 10
after stopping of the boiler caused by the overheat can be
2109719
-24-
accomplished by simply pushing the manual operation return
button RSW ~ FIG . 1 3 ), in that the button RSW is arranged
- on the control panel of control device 10 mounted to the
front door of boiler case 1 such that it exposes
outwardly. Such an arrangement of the button RSW on the
control device 10 can be made by constituting the overheat
sensor S2 by a thermistor and incorporating the overheat
sensing unit 6 in the control device 1~.
The return operation wiIl now be described in
conjunction with FIG. 13.
When the manual operation return button RSW is
pushed, the high level voltage outputted from the
comparator IC16 is bypassed into ground via the diode D31,
resistor R71, and diode D32. Accordingly, the comparator
IC17 maintains HIGH level at its non-inverting input
terminal (+) and thus outputs a low level signal. As a
result, alarm displaying of the alarming unit is stopped.
At the same time, sending of high level signal to the
inverting input terminal (-) of the comparator IC7 of
control unit 12 is shut off. At this state, the room
heating operation can be restarted by a high level signal
from the comparator IC7, and thus the boiler operates in
a normal condition.
- Since the manual operation return button RSW
connected to the safety shutoff unit 17 is connected to
the overheat sensing unit 16 in accordance with the
present invention, as mentioned above, its manipulation
for restating the boiler can be carried out without a
requirement of opening the front door of boiler case,
thereby providing a convenience. Such a requirement is
encountered in the prior art. It is noted that the
pushing manipulation of button RSW makes only the boiler
return to its restating condition.
In a normal operation of boiler, oil should be
injected into the burner device 3 by the oil pump and its
burning should be normally achieved. However, if such a
burning is not performed, then oil is undesirably
2109719
-25-
accumulated in the fire chamber due to its continued
supplying. In order to avoid an occurrence of this
phenomenon, a safety shutoff device is needed. In this
regards, the present invention provides the safety shutoff
unit 17 including the flame sensor S5 disposed adjacent to
the burner device 3.
Now, the operation of safety shutoff unit 17 will now
be described, in conjunction with FIG. 11.
When no flame (namely, burning light~ is sensed by
the flame sensor S5 during the operation of oil pump, the
inverter IC13 maintains HIGH level at its input so that
the inverter IC14 series connected to the inverter IC13
outputs a high level signal. This high level signal from
the inverter IC14 is applied to the base of transistor TR7
via the resistor R50, diode D20 and resistor R51, thereby
causing the transistor TR7 to be activated.
Simultaneously with the activation of transistor TR7, the
voltage which has flowed into the inverting input terminal
(-) of comparator IC15 flows into the collector of the
transistor T~ which is coupled at its emitter to the
collector of transistor TR7. As a result, the comparator
IC15 maintains LOW level at its inverting input terminal
(-) and thus outputs a high level signal, so that the
-light emission diode LED2 emits light to display the
abnormal condition of boiler. The output signal from the
comparator IC15 is also sent to the alarming unit, so as
to give an alarm indicative of the abnormal condition of
boiler. At the same time, the output signal from the
comparator IC15 is sent to the inverting input terminal (-
) of the comparator IC7 of control unit 12, thereby
causing the comparator IC7 to output a low level signal.
Accordingly, the operation of burner device 3 is stopped.
Also, the timer IC10 applies a low level output signal to
the oil pump drive circuit EPD3. Accordingly, the
transistor T~1 is deactivated, thereby causing the relay
RY3 for driving the electromagnetic oil pump to be
switched to its OFF state. Thus, supplying of oil is shut
~ -25- 2109719
o~f.
At this state, pushing of the manual operation return
button-RSW makes the voltage which has applied to the non-
inverting input terminal (+) of comparator IC15 flow into
ground through the button RSW. As a result, the
comparator IC15 outputs a low level signal, thereby
causing the light emission diode LED2 and the alarming
unit to be deactivated.
Since the button RSW is coupled to' the control unit
12 by a diode D12, its pushing also makes the voltage from
the control device 12 flow into ground,. thereby causing
the burner device to be deactivated. Thus, a safety is
provided even during the return operation of control
device.
As mentioned above, the control device of the present
invention also has the forcible water supply function.
Now, the forcible water supply operation of control device
1~ will be described, in conjunction with FIG. 12.
When the forcible water supply button MWB is pushed
for supplying water to the water chamber 21, the source
voltage Vcc is applied to the input terminal CP of
circulation pump drive circuit CPD4 via the diode D29 and
to the input terminal AW of water supply drive circuit
AWD5 via the diode D30. In the circulation pump drive
circuit CPD4, the transistor TR12 is acti-vated by the
signal received at its base, thereby causing the relay RY4
to be activated. By the activation of relay RY4, the
circulation pump 5 drives. In the water supply drive
circuit AWD5, the transistor TRl3 is activated by the
signal received at its base, thereby causing the relay RY5
to be activated. By the actiyation of relay RY5, the
water supply valve 72 is opened, thereby enabling
supplying of water to the water chamber 21 through the
water supply valve 72. The source voltage vcc is also
sent to both the light emission diodes LED3 and LED4, via
the resistors R65 and R67, respectively, so that the light
emission diodes LED3 and LED4 emit light to inform of both
-27- 2109719-
the operation of circulation pump 5 and the water
supplement through the water supply valve 72.
As mentioned above, the anti-fixing circuit 15 is
also provided to avoid an occurrence of fixing at the
circulation pump 5, in accordance with the present
invention. In case of, for example, selecting the water
supply mode using the room temperature controller, a
corresponding signal, namely, a water supply signal is
applied to the control unit 12 via the room signal
receiving unit 11, so that the c~ntrol unit 12 outputs an
active signal for operating the water supply system to the
output unit 13. Accordingly, the bur~er motor drive
circuit BMD1, the ignition transformer drive circuit ITD2
and the oil pump drive circuit EPD3 are activated. Thus,
water in the water chamber 21 is heated to a temperature
ranging from about 85~C to about 90~C to obtain hot supply
water at a temperature ranging from about 40~C to about
60~C. In conventional boiler systems wherein both the
burner device and the circulation pump are continuously
operated in the room heating mode, however, the
circulation pump is designed not to be operated in the
water supply mode (although the circulation pump is
generally disposed at the room heating water feedback
line, it may be disposed at the room heating water output
line, as in the embodiment of the present invention
illustrated in FIG. 6). As a result, the operation of
circulation pump is shut off for several months in the
summer season. However, the operation of water supply
system.is achieved even in the summer season, so as to
avoid an occurrence of fixing at the circulation pump 5.
Now, this anti-fixing operation will now be described
in conjunction with FIG. 16.
When a water supply signal from the room temperature
controller is sent to the room signal receiving unit 11
and thus the control unit 12 (FIG. 9), that is, when the
generation of water supply signal is recognized by the
anti-fixing circuit 15, the source voltage vcc flows
21()9719
- -28-
through the diode D42 via the resistor R~ and is also
applied to the non-inverting input terminal (+) of
comparator Q3, thereby causing the comparator Q3 to output
a high level signal. This high level signal from the
comparator Q3 is sent to the non-inverting input terminal
(+) of comparator Q4 via the charge circuit including the
condenser C21 and diode D43, so that the comparator Q4
outputs a high level signal. This high level signal from
the comparator Q4 is sent to the circulation pump drive
circuit CPD4 via the diode D24 and resistor ~9, thereby
causing the circulation pump drive cir,cuit CPD4 to be
activated. In this case, the operation time of
circulation pump 5 is determined by RC time constant of
the charge circuit and is preferably about 30 seconds to
about 40 seconds.
On the other hand, the anti-fixing circuit 15 is
constructed so that when the temperature of water in the
water chamber 21 is high, it disables the temporary
operation of circulation pump 5 even though recognizing
the water supply signal from the room signal receiving
unit 11.
That is, when the temperature sensor S1 (FIG. 10)
senses the high water temperature of above 40~C, the
comparator Q1 of sensing circuit 15A maintains LOW level
at its non-inverting input terminal (+) and thus outputs
a low level signal. Accordingly, the comparator Q2 series
connected to the comparator Q1 also outputs a low level
signal. As a result, the source voltage Vcc flows through
the diode D42, so that the comparator Q3 of circulation-
pump control circuit 15B maintains LOW level at its non-
inverting input terminal (+) and HIGH level at its
inverting input terminal (-) and thus outputs a low level
signal. Therefore, the circulation pump 5 is not
operated, in the same manner as mentioned above.
Alternatively, the anti-fixing circuit 15 may be
constructed in accordance with another embodiment of the
present invention illustrated in FIG. 17.
2109719
~_ .
-29-
In this case, the anti-fixing circuit comprises a
sensing circuit A coupled at its input terminal to the
room signal receiving unit ll and at its output terminal
to the timer circuit D including a timer MC and a
circulation pump control circuit B including an inverter
Q13, a transistor TR21 and a diode SD1, and an oscillation
circuit C coupled to the timer MC of timer circuit D and
including a pair of inverters Q14 and Q15, three resistors
~01 r ~02 and ~03. The sensin~ circùit A includes a
comparator Q11 and an inverter Q12 . The comparator Q11 is
connected at its inverting input term~nal (-) to the
temperature sensor S1 via a resistor ~ and at its non-
inverting input terminal (+).to a tap on a voltage divider
including resistors ~08 and ~ coupled between a'12V
voltage source and ground. The output terminal of
comparator Q11 is coupled to the 6th input terminal of
timer MC, by a diode SD2. The inverter Q12 is coupled at
its input terminal to the room signal receiving unit ll,
to sense a water supply signal. The output terminal of
inverter Q1z is coupled to the 6th input terminal of timer
MC, by a diode SD3. The inverter Q13 of circulation pump
control circuit B is coupled at its input terminal to the
3th output terminal of timer MC and at its output terminal
to the collector TR21 by the diode SD1. The output
terminal of inverter Q13 is also coupled to the control
unit 12 by the diode SD1 and a resistor ~11.The transistor
TR21 is coupled at its emitter to ground and at its base
to the diode SD2 of sensing circuit A, by a resistor ~.
The inverter Q14 of oscillation circuit C is connected at
its output terminal to an input terminal of the timer MC
via the resistor ~01~ The inverter Q15 series connected to
the inverter Q14 is coupled at its input terminal to the
10th output terminal of timer MC by a diode SD4. The
resistor ~02 iS coupled between the output terminal of
inverter Q105 and the junction of the diode SD4 and the
resistor ~03. With this construction, the circulation
pump 5 can be temporarily operated during the operation of
-30- 2109719
water supply system so that it is always maintained at its
normal operation condition. The anti-fixing circuit of
this embodiment may be activated upon not only sensing the
water supply signal, but also sensing an outing signal.
The operation of anti-fixing circuit with the above-
mentioned construction will now be described.
Upon pushing of the water supply button equipped in
room temperature controller, a water supply signal from
the room signal receiving unit ll is applied to the
inverter Q12 of sensing circuit A, thereby causing the
inverter Q12 to output a low level signal. At this time,
if the temperature sensor S1 senses the water
temperature of not more than 40~C in the water chamber 21,
the comparator Q11 maintains HIGH level at its inverting
input terminal and thus outputs a low level signal. This
low level signal from the comparator Q11 is sent to the
6th input terminal of the timer MC, so that the timer MC
is activated and outputs a low level signal at the 3th
output terminal thereof for a predetermined period. In
response to the low level signal from the timer MC, the
inverter Q3 of circulation pump control circuit B outputs
a high level signal which is, in turn, applied to the
control unit 12. Thus, the circulation pump 5 is operated
for several ten seconds.
- At the same time, the timer MC outputs a high level
signal at the l0th output terminal thereof. In response
to this signal from the timer MC, the oscillation circuit
C oscillates to make the timer MC initiate its timing
operation.
When the timing operation of timer MC is switched to
OFF state after the lapse of the setting time during which
outputting of the low level signal is maintained at the
3th output terminal thereof, the voltage level at the 3th
terminal is switched to High level. As a result, the
inverter Q3 of circulation pump control circuit B outputs
a low level signal, thereby the circulation pump 5 to be
- deactivated. In a manner similar to that of the above-
2109~19
~_ -31-
mentioned embodiment illustrated FIG. 16, when the water
temperature in the water chamber 21 is above ~0~C, the
comparator Ql1 maintains LOW level at its inverting input
terminal and thus outputs a high level signal. In
response to this high level signal, the timer MC and thus
the circulation pump 5 are deactivated.
The transistor TR21 ~f circulation pump control
circuit B is activated by a high level signal from the
comparator Q11 and serves to bypass the circulation pump
driving signal from the timer MC.
As apparent from the above descriptcion, the present
invention provides a hot water boiler of the type of an
operation under no pressure comprising a water supplement
tank disposed in a boiler case and having a water
expansion function, thereby capable of achieving a smooth
room heating water circulation under atmospheric pressure.
In accordance with the present invention, water expansion
and supplement operations are automatically accomplished
without any water supplying from external, so that the
content of oxygen dissolved in the room heating water is
minim;zed (upon being subjected to heat, oxygen in water
is vaporized and forms air bubbles which will be vent to
atmosphere through the supplement water tank).
Accordingly, it is possible to reduce the loss of heat,
eliminate an inconvenience caused by a periodical air
venting work, and avoid an occurrence of corrosion
phenomenon. When a shortage of room heating water occurs
during the operation of boiler, a supplement of room
heating water is accomplished by an opening operation of
a water supply valve based on a low water level sensing
operation of a low water sensor, in accordance with the
present invention. Since the supplement water tank having
a water pressure control function is arranged in the
interior of boiler, the overall size of boiler can be also
compact. Furthermore, it is possible to easily carry out
boiler installation and piping works, avoid a
contamination of room heating water and provide an
2109719
-32-
improvement in safety. In accordance with the present
invention, there is also provided a manual operation
return button equipped in a control device. By the
provision of manual operation return button, there is
obtained advantageous functions of releasing an operation
shutoff caused by an occurr~ence of overheat and of
forcibly supplying water. Accordingly, it is possible to
provide a reliable boiler having improvements in safety
and utility. In accordance with the present invention,
temperature sensors for sensing the overheat and the
temperature of room heating water are comprised of
thermistors which can be integrated into a single sensor.
Therefore, there is an effect of providing both the
overheat sensing function and the room heating water
temperature sensing function, with a single sensor. In
accordance with the present invention, the return
operation for releasing an operation shutoff caused by an
occurrence of overheat is achieved by the control device,
thereby obtaining a convenience in use. When a shortage
of water occurs during the operation of boiler, the
present invention also makes it possible to sense the
shortage of water, safely shut off the operation of boiler
upon the sensing and simultaneously supply water to
-replenish the shortage, thereby improving an efficiency in
operation. The control device also includes a circulation
pump anti-fixing circuit which enables an intermittent
operation of the circulation pump in every hot water
supply operation. Such an intermittent operation of the
circulation pump makes it possible to prevent fixing of
impellers, thereby preventing an accident possibly caused
by the fixing of impellers and lengthening the life of
circulation pump. In particular, there is provided a
safety circuit which prevents the boiler from operating
during the return operation for releasing an boiler
operation shutoff for a safety. Thus, the present
invention provides a boiler exhibiting an improvement in
safety and a convenience in use.
