P7710
Solid State Pressure Sensor
Boiler Control System 7700
The P7710 is a solid state steam pressure
sensor designed for use with the BCS 7700. The
P7710 utilizes a solid state pressure transducer
to provide indication of steam pressure. When
steam pressure is applied to the P7710, an internal diaphragm flexes, resulting in a low level
voltage output proportional to the steam pressure.
The P7710 is Underwriters Laboratories Inc.
component recognized, Canadian Standards
Association certified and Factory Mutual approved.
■ On/off operating control and modulating control
of burner firing rate.
■ Four available pressure ranges:
.75 - 15 psi.
7.5 - 150 psi.
15 - 300 psi.
37.5 - 750 psi.
■ Upper housing wiring enclosure with provisions
for 1/2 in. conduit connector.
■ NEMA 3 rated enclosure.
■ Pipe fitting, female 1/4 in. NPT thread.
■ Sensor-applied pressure causes internal diaphragm to flex, resulting in low level output voltage proportional to the steam pressure.
■ Solid state technology.
CONTENTS
Specifications ................................................ 2
Ordering Information .................................... 2
Installation .................................................... 3
Wiring ............................................................ 4
Operation and Checkout ............................... 8
T.M. • Rev. 10-91 • © Honeywell Inc. 1991 • Printed in U.S.A. • Form Number 63-2274—1
P7710
SPECIFICATIONS • ORDERING INFORMATION
Specifications
ACCESSORIES:
14026 Siphon Loop.
Fig. 1—P7710 steam pressure sensor dimensional diagrams.
ELECTRICAL RATINGS:
Input/output leadwires:
Red lead 8 Vdc +/- .05 Vdc (Supply).
Black lead (Common).
Blue lead 1.25 - 5.75 Vdc (Signal).
Power Dissipation:
250 milliwatts maximum.
2 (50.8)
4-7/8
MAX.
(123.8)
ENVIRONMENTAL RATINGS:
Ambient Temperature:
Operating 32˚F to 150˚F.
Storage -32˚F to 150˚F.
Humidity:
Operating 85% RH continuous, noncondensing.
Vibration:
0.5G continuous maximum.
Dimensions:
See Fig. 1.
Connections:
1/4 in. NPT female thread.
4
(101.6)
1-3/32
(27.8)
1/4 NPT (6.3)
1-7/8
(47.6)
APPROVAL BODIES:
Underwriters Laboratories Inc. Component recognized.
Canadian Standards Association certified.
Factory Mutual approved.
3-5/8
MAX.
(92.1)
3/4 (19)
ACROSS
HEX FLATS
3-3/4 MAX. (95.2)
M2034B
Ordering Information
When purchasing replacement and modernization products from your BCS 7700 distributor, refer to the TRADELINE Catalog for
complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1. Your local Honeywell Residential and Building Controls Sales Office (check white pages of your phone directory).
2. Residential and Building Controls Customer Satisfaction
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386 (612) 542-7500
In Canada—Honeywell Limited/Honeywell Limitee, 740 Ellesmere Road, Scarborough, Ontario M1P 2V9 International Sales
and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan,
Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
2
P7710
SPECIFICATIONS • INSTALLATION
Model
Max
Scale
Range
(psi)
Max
Scale
Range
(kPA)
P7710A1047
P7710A1054
P7710A1062
P7710A1070
.75-15
7.5-150
15-300
37.5-750
5.2-130.1
51.7-1033
103.3-2061
258.4-5152
Signal
Range
(Vdc)
Tolerance
(+/- %)
1.25-5.75
4%
Sustained
Pressure
(psi)
Sustained
Pressure
(kPA)
22.5
225
450
1125
154.6
1545.7
3091
7728.1
Installation
WHEN INSTALLING THIS PRODUCT. . .
1. Read these instructions carefully. Failure to follow
them could result in a hazardous condition or cause
damage to the product.
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for the
application.
3. Installer must be a trained experienced service technician.
4. After installation is complete, check out product
operation as provided in these instructions.
MOUNTING PROCEDURE
1. Be sure the boiler is not firing and zero steam
pressure exists in the boiler vessel.
2. Disconnect power to the BCS 7700 so the boiler
cannot sequence during installation of the steam pressure
sensor.
3. Remove the protective plug cap from the 1/4 in NPT
piping.
4. Make all pipe connections in accordance with approved standards. Apply only a small amount of pipe
compound; excess compound may clog the small hole in
the fitting and prevent proper operation.
CAUTION
IMPORTANT: To avoid leaks and case damage, use a
parallel jaw wrench on the hexagonal part of the case
close to the mounting pipe. Make all connections carefully and test for leakage. Do not tighten the pressure
sensor by hand.
Disconnect power supply before beginning installation to prevent possible equipment damage
or electrical shock, more than one disconnect
may be involved.
5. Complete remaining required system piping.
6. Install other controls in the system, connect wiring,
and complete setting and checkout of the sensor.
IMPORTANT:
1. Locate the sensor where the ambient temperature
will not exceed 150˚F.
2. Use pipe compound sparingly to avoid clogging the
hole in the pipe or diaphragm fitting.
3. Do not tighten the sensor by hand.
4. The sensor should be mounted in a steam trap
(siphon loop), in a vertical position. The unit should
be mounted with the 1/4 in. NPT connection facing
downward (see Fig. 2).
Fig. 2—Steam pressure sensor location.
MANUAL
RESET
HIGH LIMIT
P7710
STEAM PRESSURE
CONTROL
STEAM
PRESSURE
HEADER
MOUNTING
The P7710 sensor provides a 1/4 in. NPT female fitting
for connection to the steam header. When used with steam
boilers always mount the sensor above the water line in the
boiler. A steam trap (siphon loop) must be connected
between the sensor and boiler header (see Fig. 2) to
prevent boiler scale and corrosive vapors from attacking
the pressure sensor element.
The sensor may be mounted:
• alongside the pressure gage.
• in a fitting on the boiler.
• at a remote location in case of excessive vibration.
BOILER VESSEL
M592
3
63-2274—1
P7710
WIRING
Wiring
CAUTION
Fig. 3—Steam sensor electrical enclosure.
Disconnect the power supply before connecting
wiring to prevent electrical shock and equipment
damage; more than one disconnect may be involved.
COVER
1. All wiring must agree with applicable codes, ordinances, and regulations.
2. Upper housing provides wiring enclosure with provisions for 1/2 in. conduit connection.
3. DO NOT overload the sensor. See ACCESSORIES
above.
4. Pressure sensor requires a shielded three wire conductor cable that is UL listed for temperatures and voltages encountered in the application. Suggested cables
include:
a. Belden 9365, rated for 300V service at 105˚ C or
equivalent.
b. Belden 8770, rated for 300V service at 60˚ C or
equivalent.
5. Do not connect the shield to anything at the sensor
end; it should be clipped and taped to avoid unintended
contact with the sensor housing. At the BCS 7700 end, the
shield must be grounded to the CONTROL PANEL with
the lead wire length as short as practical.
6. Do not route sensor leadwires in conduit with line
voltage circuits.
7. Avoid routing sensor leadwires close to the ignition
transformer leadwires.
8. Route sensor leadwires outside of conduit if properly supported and protected from damage.
9. Be sure maximum sensor leadwire length is 100
feet.
10. Wire the P7710 according to Fig. 10 and 11.
11. Complete required checkout procedures as indicated in these instructions and return the system to normal
operation.
12. Utilize wire nuts provided.
LEAD
WIRES
M15593
SETTINGS AND ADJUSTMENTS
The P7710 adjustment is made through the Keyboard
and Display Module (see Fig. 4). The Keyboard and
Display Module is the primary user interface to the
system. It consists of a keyboard, LCD display and three
status LEDs. The module is used to program the controller
and display boiler operating status and parameters.
To ensure proper understanding of the Keyboard and
Display Module and that programming is performed correctly, read forms 63-2287 and 63-2290. Failure to read
the reference manual results in a higher probability of user
error. Reading the reference manual makes system operation straight forward. For proper steam pressure control,
five settings are required: sensor range, operating setpoint,
boiler on, response and boiler off. To make these settings,
refer to the Programming Specifications, form 63-2290.
Operation and Checkout
• Operating Set point—Determines the desired operating pressure, midpoint of control band, point P2,
Fig. 5.
• Response—Determines the width of the control
band, point P3, Fig.5.
• Boiler On—Determines the pressure level that initiates a boiler cycle, point P1, Fig. 5.
• Boiler Off—Determines the pressure level which
terminates a boiler cycle, point P4, Fig. 5.
OPERATION
The P7710 is a solid state steam pressure sensor which
incorporates a pressure transducer. The pressure transducer uses a stainless steel diaphragm coupled to semiconductor strain gauges. The transducer is powered from the
BCS 7700.
As pressure flexes the diaphragm, the resistance values
change causing a bridge circuit imbalance that is amplified with an internal amplifier. The resulting voltage
output is proportional to the pressure causing the diaphragm to flex. This output voltage is amplified to a 1.25
- 5.75 Vdc range.
The BCS 7700 compares the amplified 1.25 - 5.75 Vdc
signal to the programmed setpoints and the boiler sequence is affected according to the functions of each set
point:
• Sensor Range—Selects the proper range of sensor
operation based on the sensor used; i.e., 15 psi.
Firing Rate Control
The rate control determines what the firing rate of the
burner should be during the run period. Steam pressure is
monitored and processed by the BCS 7700 rate control to
select a firing rate which minimizes load pressure variations, reduces on-off cycling, and minimizes firing rate
motor adjustments. The firing rate control for hot water or
4
P7710
OPERATION AND CHECKOUT
at low fire until pressure drops to the Operating Set point
(OperSet point), point P2. At this point, the burner is
allowed to modulate under the control of the firing rate
control .
The rate control will control the pressure with a control
band as defined by the response factor. One of five
response factors can be chosen to determine the tightness
of control. A response factor of 5 provides very tight
control that requires numerous firing rate motor repositions. A response factor of 1 is loose control that does not
require numerous firing rate motor repositions.
As pressure rises, the burner will shut down at point P4,
Boiler Off.
Fig. 4—Keyboard and display module.
CHECKOUT
For detailed troubleshooting and programming procedures, refer to the Troubleshooting and Programming
specifications, forms 63-2291 and 63-2290.
1. Turn the burner switch off to place the BCS 7700 in
the Standby mode.
2. Use the Keyboard and Display Module to determine
the actual steam pressure.
3. Use the Keyboard and Display Module to determine
the voltage signal that is present at the sensor.
4. Check the readings obtained in steps 2 and 3 against
the appropriate graph, voltage output to steam pressure,
based on the sensor’s pressure range. These values should
be within +/- 4%. If these values are incorrect, refer to
Troubleshooting section, form 63-2291 for corrective
action.
5. Return the boiler to normal operation.
steam boilers is the same except for the inputs from the
sensor. Refer to Fig. 5 for a graphic representation of the
firing rate control.
Rate Control
A burner sequence begins when operating pressure
reaches the Boiler On setting, point P1. The burner is held
Fig. 5—Rate control response.
Fig. 6—Pressure to voltage .75-15 psi range.
TEMPERATURE OR
PRESSURE
SOLID STATE STEAM PRESSURE SENSOR
PRESSURE VS. VOLTAGE
INPUT - 8.0 VDC LIMITED SUPPLY
15
BOILER OFF
P1
PSI
BOILER ON
P4
7.5
1.5
P2
OPERATING
SET POINT
0
RESPONSE (P3)
1.25 1.70
3.50
OUTPUT, VDC
5.75
M1070A
TIME
P = PRESSURE OR TEMPERATURE POINT
M582A
5
63-2274—1
P7710
OPERATION AND CHECKOUT
Fig. 7—Pressure to voltage 7.5-150 psi range.
Fig. 8—Pressure to voltage 15-300 psi range.
SOLID STATE STEAM PRESSURE SENSOR
PRESSURE VS. VOLTAGE
SOLID STATE STEAM PRESSURE SENSOR
PRESSURE VS. VOLTAGE
INPUT - 8.0 VDC LIMITED SUPPLY
INPUT - 8.0 VDC LIMITED SUPPLY
300
PSI
PSI
150
75
150
15
30
0
1.25
0
1.25 1.70
3.50
OUTPUT, VDC
5.75
1.70
3.50
OUTPUT, VDC
M1071A
Fig. 9—Pressure to voltage 37.5-750 psi range.
SOLID STATE STEAM PRESSURE SENSOR
PRESSURE VS. VOLTAGE
INPUT - 8.0 VDC LIMITED SUPPLY
PSI
750
375
75
0
1.25
1.70
3.50
OUTPUT, VDC
6
5.75
M601
5.75
M600
P7710
OPERATION AND CHECKOUT
Fig. 10—BCS 7700 internal block wiring diagram.
L1
L2
(HOT)
E
EARTH GROUND
3
OIL
52
OIL SELECT
53
GAS SELECT
49
120 VAC
GAS
11K1
55
54
50
OPTOISOLATOR
INPUTS
19 LOAD
DEMAND
14 ALARM
SIGNAL
32
8
18
13
23
OIL TEMP.
SENSOR
COMMON
35
8K1
9K1
2
SIGNAL
34
24VDC
WATER TEMP.
SENSOR / CONFIG. ANALOG
COMMON
33
TEMPERATURE
SENSOR
AMPLIFIER
DIGITAL
MONITOR
51
8K2
9K2
ATOMIZING AIR
COMPRESSOR
MOTOR STARTER
56
10K1
DIGITAL
MONITOR
20
15
OIL LINE
PURGE VALVE
2
7K2
POWER (RED)
RELAY
DRIVE
CIRCUIT
SENSOR
POWER
SUPPLY
10K
36
SIGNAL (BLUE)
37
5
11K
COMMON (BLACK)
38
SIGNAL (BLUE)
COMMON (BLACK)
44
SIGNAL (BLUE)
46
COMMON (BLACK)
47
SAFETY
1K
RELAY
CIRCUIT
OPTOISOLATOR
INPUTS
A
B
C
RS485
2
GAS
PRESSURE
SENSOR
2
25
26
3K
RELAY
DRIVE
CIRCUIT
OIL
PRESSURE
SENSOR
24
FIRING
RATE
24VDC
2K
21
POWER (RED)
45
PROGRAM MODULE AND
CHASSIS MODULE INTERFACE
2
POWER (RED)
42
MICROCOMPUTER
8
COMMON
41
43
RUN-TEST
SWITCH
7K1
SIGNAL
40
ANALOG
TO
DIGITAL
CONVERTOR
22 UNUSED
2
POWER
39
RESET
PUSHBUTTON
STEAM
PRESSURE
SENSOR /
CONFIG.
ANALOG
27
4K
6K
ALARM
RELAY
7K
9K
28
PLUG IN
FLAME
AMPLIFIER
FLAME
DETECTOR
29
8K
30
1
7
31
6K1
L2
BURNER
MOTOR
STARTER
4
L1
PREINGINTION
INTERLOCKS
5
BURNER
SWITCH
7
RECYCLE
LIMITS
LOCKOUT
INTERLOCKS
6
1K1
PILOT
VALVE
4K1
8
IGNITION
TRANSFORMER
10
F1, 10A
3K1
OIL MAIN
VALVE
11
2K1
ATOMZING
AIR PROVING 16
SWITCH
GAS PRESSURE
SENSOR TEST VALVE
GAS MAIN
VALVE
12
120VAC
40VA
KEYBOARD AND DISPLAY
FIRING RATE MOTOR
24VAC
2
LIQUID CRYSTAL DISPLAY
A
B
C
3
OPEN
RS485
1
MICROCOMPUTER
9
KEYBOARD
CLOSE
INDICATES FEEDBACK SENSING TO
OPTOISOLATORS
G
T
Y
1
2
3
WIRING SHOWN FOR INFRED FLAME DETECTOR FOR C7027
ULTRA VIOLET FLAME DETECTOR WIRE AS NOTED BELOW
– ULTRA VIOLETDECTECTOR BLUE LEAD - TERMINAL 31
– ULTRA VIOLET DETECTOR WHOTE LEAD - TERMINAL 30
THE ULTRA VIOLET FLAME DETECTOR WIRING IS POLARITY SENSITIVE,
REVERSING THE LEDS WIRES MAY DAMAGE THE SENSOR.
FOR ULTRA VIOLET C7012E,F WIRE AS NOTED BELOW:
– BLUE LEAD - TERMINAL 31
– YELLOW LEAD - TERMINAL 29
– WHITE LEAD - TERMINAL 27
– WHITE LEAD - L2
– BLACK LEAD - L1
– BLACK LEAD - L2
WIRE THESE TERMINALS WITH SHIEDLED CABLE PER SPECIFICATION.
THE CABLE SHIELD SHOULD NOT BE CONNECTED AT THE SENSOR END
AND SHOULD BE TAPED TO AVOID UNINTENTIONAL CONTACT. AT THE
BOILER CONTROLLER END, THE SHIELD WIRES MUST BE GROUNDED
TO THE CONTROL PANEL WITH AS SHORT AS POSSIBLE A LEAD LENGTH.
4
DO NOT CONNECT WIRES TO ANY UNUSED TERMINALS.
TERMINALS 9, 17, 21, 22, 23, 28, 48 ARE NOT USED.
5
POWER SUPPLY FOR SYSTEM SENSORS.
6
FIELD WIRING
INTERNAL CIRCUITRY.
7
SEE FLAME DETECTOR WIRING FIGURE IN FORM NO 63-2991.
8
SEE TYPICAL STACK TEMPERATURE SETUP FIGURE
IN FORM 63-2991.
9
USE 120 OHM TERMINATING RESISTOR ON DEVICE FURTHEREST
FROM BC7700 CHASSIS MODULE (120 OHM TERMINIATING
RESISTOR INSTALLED BETWEEN TERMINALS A AND B.)
M602C
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
7
63-2274—1
120V
LINE
(HOT)
3
LINE
COMMON
1
MOV
Residential and
Building Controls Division
Honeywell Limited—Honeywell Limitée
740 Ellesmere Road
Scarborough, Ontario
M1P 2V9
J2
12
N/C
15
GAS
MAIN
VALVE
14
J3
16
13
17
UNUSED
OIL
MAIN
VALVE
AAPS
11
20
18
21
N/O
22
COM
N/O
19
23
N/C
COM
1
24
CLOSE
M741B
3
25
2
COM
ALARM AAPS
N / O COM N / C
LOAD
DEMAND
UNUSED
FIRING
RATE
MOTOR
26
G
27
SHTR
OPEN
T
28
UNUSED
Y
LINE COMMON
120V
24V
WIRING SHOWN FOR C7015 INFRARED FLAME DETECTOR, FOR C7027 ULTRA VIOLET
FLAME DETECTOR WIRE AS NOTED BELOW:
– ULTRA VIOLET DETECTOR BLUE LEAD - TERMINAL 31
– ULTRA VIOLET DETECTOR WHITE LEAD - TERMINAL 30.
THE ULTRA VIOLET FLAME DETECTOR WIRING IS POLARITY SENSITIVE, REVERSING THE
LEDS WIRES MAY DAMAGE THE SENSOR. FOR ULTRA VIOLET C7012E,F WIRE AS NOTED
BELOW:
– BLUE LEAD - TERMINAL 31
– YELLOW LEAD - TERMINAL 29
– WHITE LEAD - TERMINAL 27
– WHITE LEAD - L2
– BLACK LEAD - L1
– BLACK LEAD - L2
GAS
PILOT
VALVE
10
9
LOCKOUT
INTERLOCKS
7
8
DEMAND
6
PREIGNITION
INTERLOCKS
BURNER
MOTOR
STARTER
L1
EARTH
GROUND
L2
RECYCLE
LIMITS
5
4
J1
29
30
J7
WATER
TEMP.
33
2
6
WATER
TEMP.
SENSOR
32
OIL
TEMP.
35
2
OIL
TEMP.
SENSOR
34
STEAM
PRESSURE
ATOMIZING AIR COMPRESSOR
MOTOR STARTER
L1
OIL LINE
PURGE VALVE
GAS SELECT
OIL SELECT
37
38 39
2
6
STEAM
PRESSURE
SENSOR
36
40
41
2
UPPER PROGRAM MODULE CONNECTOR
LOWER PROGRAM MODULE CONNECTOR
GAS
MOTOR
OIL
POSITION
PRESSURE PRESSURE
PROGRAM MODULE
43
44
2
OIL
PRESSURE
SENSOR
42
46
47
2
GAS
PRESSURE
SENSOR
45
J8
DO NOT CONNECT WIRES TO ANY UNUSED TERMINALS. TERMINALS 9, 17, 21, 22, 23, 28, 48 ARE NOT USED.
SEE FLAME DETECTOR WIRING FIGURE.
SEE TYPICAL STACK TEMPERATURE SETUP FIGURE.
USE 120 OHM TERMINATING RESISTOR ON DEVICE FURTHEST FROM BC7700 CHASSIS MODULE (120 OHM
RESISTOR INSTALLED BETWEEN TERMINALS A AND B).
M1924A
5
6
7
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
WIRE THESE TERMINALS WITH SHIEDLED CABLE PER SPECIFICATION SHEET. THE CABLE SHIELD SHOULD
NOT BE CONNECTED AT THE SENSOR END AND SHOULD BE TAPED TO AVOID UNINTENTIONAL CONTACT. AT
THE BOILER CONTROLLER END, THE SHIELD MUST BE GROUNDED TO THE CONTROL PANEL WITH AS SHORT
A LEAD LENGTH AS POSSIBLE.
56
55
54
53
52
TERMINAL 51
TERMINAL 50
4
3
2
ATOMIZING AIR
COMP.
PURGE
VALVE
GAS
OIL
51
50
Fig. 11—BCS 7700 field wiring diagram.
IGNITOR
BMSI
CAPS
LMTS
BS
LWCO
MGV
BURNER
MOTOR
STARTER
3
2
1
G
SIGNAL
F2
SIGNAL
CHASSIS
MODULE
L2
COMMON
49
COMMON
31
SIGNAL
F1
POWER
PLUG-IN FLAME
AMPLIFIER
LINE HOT
UNUSED
COMMON
48
POWER
5
SIGNAL
1
COMMON
J4
SIGNAL
J10
POWER
7
UNUSED
COMMON
J9
PILOT
VALVE
IGNITION
SIGNAL
A
B
C
OIL MAIN
VALVE
GAS MAIN
VALVE
POWER
Residential and
Building Controls Division
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, Minnesota 55422
COMMON
KEYBOARD / DISPLAY
MODULE
P7710
OPERATION AND CHECKOUT
QUALITY IS
KEY