Honeywell C645A-E User Manual
60-2159-8
C645A,B,D,E
C645A,B with Window
C645C
GENERAL
The C645 pressure switches are safety devices used in
positive-pressure or differential-pressure systems to sense
gas or air pressure changes.
C645A-E
Pressure Switches
PRODUCT DATA
FEATURES
• C645A,B models are for use on natural gas, LP gas,
or air.
• C645B1047 includes a scaleplate stop to meet
American Gas Association (AGA) requirements for
gas-fired boilers with inputs over 2-1/2 million Btuh.
• C645C,D models are for use on air only.
• C645E for use with distillate fuel oil.
• Spring-loaded diaphragm actuates snap-acting
Micro Switch.
• Switch can be wired to turn on alarm.
• C645A,C and D models break control circuit on
pressure fall.
• C645B models break control circuit on pressure rise.
• Lockout and manual reset optional in A and C models.
• Removable, zinc-plated cover protects scaleplate and
adjusting screw.
• Lockout models have external manual reset lever.
• Pipe tappings allow selection of positive pressure,
differential-pressure, or venting connections.
• Optional switch position indicator available.
• Models of C645A,B available with cover window for
setpoint visibility.
• Buna-N fiber-reinforced material for increased control
diaphragm strength.
• Two seal-off diaphragms for added reliability.
Copyright © 1995 Honeywell Inc. • All Rights Reserved
Contents
General ............................................................................... 1
Features .............................................................................. 1
Specifications ...................................................................... 2
Ordering Information ........................................................... 2
Installation ........................................................................... 4
Settings and Adjustments ................................................... 6
Operation and Checkout ..................................................... 7
C645A-E PRESSURE SWITCHES
SPECIFICATIONS
Models:
C645A,C,D Pressure Switches—break a circuit when
pressure falls to scale setting minus the differential.
Refer to Table 1.
C645B Pressure Switches—break a circuit when pressure
rises to scale setting. Refer to Table 1.
C645E—breaks circuit when pressure falls to scale setting
minus the differential. Refer to Table 1.
Table 1. Pressure switch model selection.
Differential
Scale
Models (in. wc) (kPa) Gas Air Action Indicator
C645A 3 to 21 0.7 to
C645B 3 to 21 0.7 to
C645C 0.6 to
C645D 3 to 21 0.7 to
C645E 3 to 21 0.7 to
a
Locks out when pressure falls to setpoint minus differential; can be reset manually after pressure rises to setpoint.
b
Locks out when pressure rises to setpoint; can be manually reset after pressure falls to setpoint minus differential.
c
Without indicator on Auto Recycle; with indicator on Lockout model.
d
With surge orifice.
Range
5 to 35 1.2 to
5 to 35 1.2 to
5.3
2 to 20d0.5 to 5 No Yes Auto Recycle No 1 3 0.2 0.7 5 34.5 No
Scale
Range
5.2
8.7
5.2
8.7
0.1 to
1.3
5.2
5.2
Natural
or LP
Yes Yes Auto Recycle
Yes Yes
Yes Yes Lockout
Yes Yes Yes 1 4 0.2 1.0 5 34.5 Yes
No Yes Auto Recycle
No Yes Auto Recycle No 1 3 0.2 0.7 5 34.5 No
No Yes Auto Recycle No 1 3 0.2 0.7 5 34.5 No
Switching
or Lockout
b
or Lockout
Switch
Position
Optional 1 3 0.2 0.7 5 34.5 Optional
a
c
Yes 1 3 0.2 0.7 5 34.5 Optional
Optional 0.2 0.8 0.05 0.02 1.5 10.3 No
a
Range
(in. wc)
Nom. Max. Nom. Max.
1 4 0.2 1.0 5 34.5 Yes
Differential
Range
(kPa)
Maximum
Surge
Pressure
(psi) (kPa) Window
Maximum
Pressure Cover
Surge
Switch Ratings (Amperes):
Model 120 Vac 240 Vac
C645A Full Load 7.4 3.7
C645B Locked Rotor 44.4 22.2
C645D
C645C Full Load 8.0 5.1
Alternate Electrical Ratings when used with Honeywell
Flame Safeguard Programmers (all C645 models):
Ignition
540 VA
Transformer
Pilot Valve 50
Main Valve 250 VA with 10 times inrush.
400 VA with 2-1/2 times inrush.
Locked Rotor 48.0 30.6
C645E Full Load 7.4 3.7
Locked Rotor 44.4 22.2
All models also rated 2A at 30 Vac.
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or your distributor, refer to the
TRADELINE® catalog or price sheets for complete ordering number, or specify—
1. Order number. 3. Optional specifications.
2. Air or gas control on C645A,B models. 4. Accessories, if desired.
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 Home and Building Control Sales Office (check white pages of your phone directory).
2. Honeywell Home and Building Control Customer Relations
Honeywell, 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9. 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.
60-2159—8
2
C645A-E PRESSURE SWITCHES
Switching:
Spdt Micro Switch snap-acting switch (Fig. 3).
Minimum Ambient Temperature:
-20°F (- 29°C).
Maximum Ambient Temperature:
125°F (52°C).
Connections:
1/4-18 NPT female tapping for main or high pressure
connection.
1/8-27 NPT female tapping for venting or low-pressure
connection.
Approvals:
Underwriters Laboratories Inc. listed: C645AE File
no. MP2168, Guide no. MFHX; for use in ambient
temperatures normally prevailing in occupiable spaces,
which usually are not higher than 77°F (25°C) but can
occasionally be as high as 104°F (40°C) for brief periods.
2-7/8 (73)
Canadian Standards Association listed: C645A-E, File no.
LR1620-369, Guide no. 140-A-2; for use subject to
same ambient temperature restrictions as Underwriters
Laboratories Inc.
Factory Mutual Approved.
Industrial Risk Insurers: C645A-D models with window in
cover approvable for applications on burners over
5 million Btuh (5 thousand cfh) input.
Optional Specifications:
1. C645A with position indicator and manual reset.
2. C645A operation to 1.5 in. WC with position indicator
and manual reset.
3. C645B with position indicator and manual reset.
4. C645C with position indicator and manual reset.
5. C645D with 2 in. (50.8 mm) differential.
Accessories:
1. C645A,B,D: Mounting Bracket: part no. 15865AC.
2. C645C: Mounting Bracket: part no. 112657A.
3. C645A: Cover with Window: part no. 137637B.
4. C645B: Cover with Window: part no. 137637C.
3-1/2 (88.9)
MOUNTING
BRACKET
(OPTIONAL)
4
3-1/2
(88.9)
3/8
(9.5)
1
IMPORTANT: FOR MODELS WITH LOCKOUT, DO NOT OBSTRUCT MANUAL RESET LEVER.
1-1/8
(28.6)
(101.6)
Fig. 1. Dimensions of C645A,B,D, and E in in. (mm).
4-3/4
(120.6)
1
2-1/2 (63.5)
1-5/16
(33.3)
5/8
(15.9)
3/16 (2)
(4.8)
1/4-18 NPT
1/8-27 NPT
3/8 (9.5)
M7564
3
60-2159—8
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