Honeywell RM7838A Installation Instructions Manual

RM7838A

66-1087-2

7800 SERIES Relay Modules

INSTALLATION INSTRUCTIONS

APPLICATION

The Honeywell RM7838A is a microprocessor-based
integrated burner control for semi-automatically fired gas, oil,
or combination fuel single burner applications. The RM7838A
Relay Module is intended to replace the Industrial
R4138A,B,C and D Flame Safeguard Primary Control, but
does not include an override on momentary power
interruptions. The RM7838A System consists of a relay
module, keyboard display module, subbase, amplifier and
purge card. Options include Personal Computer Interface,
Data ControlBus Module™, remote display mounting, first-out
expanded annunciator and Combustion System Manager
Software.

Functions provided by the RM7838A include semi-automatic
burner sequencing, flame supervision, system status
indication, system or self-diagnosis and troubleshooting.

This document provides installation and static checkout
instructions. Other applicable publications are:

63-2278 Q7700 Network Interface Unit Product Data.
65-0084 Q7800A,B 22-Terminal Wiring Subbase Product

Data.

65-0089 ST7800A Plug-in Purge Timer Installation

Instructions.
65-0090 S7800A Keyboard Display Module Product Data.
65-0091 S7810A Data ControlBus Module™ Product

Data.
65-0101 S7830 Expanded Annunciator Product Data.
65-0109 R7824, R7847, R7848, R7849, R7861, R7886

Flame Amplifiers for the 7800 SERIES Product Data.
65-0131 221818A Extension Cable Assembly
65-0229 7800 SERIES Relay Modules Checkout and

Troubleshooting.

®

SPECIFICATIONS

Electrical Ratings, see Table 3:

Voltage and Frequency: 120 Vac (+10/-15%), 50/60 Hz

(±10%).
Power Dissipation: 10W maximum.
Maximum Total Connected Load: 2000 VA.
Fusing Total Connected Load: 20A maximum, type FRN

or equivalent.

Environmental Ratings:

Ambient Temperatures:

Operating: -40°F to 140°F (-40°C to 60°C).
Storage: -40°F to 150°F (-40°C to 66°C).

Humidity: 85% relative humidity continuous,

noncondensing.

Vibration: 0.5G environment.

Approvals:

Underwriters Laboratories Inc. Listed: File No. MP268,

Guide MCCZ.
Canadian Standards Association Certified: LR9S329-3.
Factory Mutual Approved: Report No. J.I.1V9AO.AF.
Industrial Risk Insurers: Acceptable.
Federal Communications Commission: Part 15, Class B,

Emissions.

INSTALLATION

When Installing this Product...

1. Read these instructions carefully. Failure to follow them
could damage the product or cause a hazardous
condition.

2. Check the ratings given in the instructions and marked
on the product to make sure the product is suitable for
your application.

3. Installer must be a trained, experienced, flame
safeguard technician.

4. After installation is complete, check out the product
operation as provided in these instructions.

WARNING

Fire or Explosion Hazard.
Can cause property damage, severe injury,
or death.

Verify safety requirements each time a control is
installed on a burner.

CAUTION

Electrical Shock Hazard.
Can cause electrical shock or equipment/
control damage.

Disconnect the power supply before beginning
installation.

® U.S. Registered Trademark
Copyright © 1998 Honeywell Inc. • All Rights Reserved

RM7838A 7800 SERIES RELAY MODULES

IMPORTANT

1. Wiring connections for the relay module are unique;
refer to Fig. 2 or the correct Specifications for proper
subbase wiring and sequence charts.

2. Wiring must comply with all applicable codes,
ordinances and regulations.

3. Wiring must comply with NEC Class 1 (Line Voltage)
wiring.

4. Loads connected to the RM7838A must not exceed
those listed on the RM7838A label or the
Specifications; see Table 3.

5. Limits and interlocks must be rated to simultaneously
carry and break current to the ignition transformer, pilot
valve, and main fuel valves.

6. All external timers must be listed or component­recognized by authorities having proper jurisdiction.

7. For on-off gas-fired systems, some authorities who
have jurisdiction prohibit the wiring of any limit or
operating contacts in series between the flame
safeguard control and the main fuel valve(s).

8. Two flame detectors can be connected in parallel with
the exception of Infrared Flame Detectors (C7015).

9. This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in
accordance with the instructions, can cause
interference with radio communications. It has been
tested and found to comply with the limits for a Class B
computing device of Part 15 of FCC rules, which are
designed to provide reasonable protection against such
interference when operated in a commercial
environment. Operation of this equipment in a
residential area can cause interference, in which case,
users, at their own expense, may be required to take
whatever measures are required to correct this
interference.

10. This digital apparatus does not exceed the Class B
limits for radio noise for digital apparatus set out in the
Radio Interference Regulations of the Canadian
Department of Communications.

Location

Humidity

Install the relay module where the relative humidity never
reaches the saturation point. The relay module is designed to
operate in a maximum 85% relative humidity continuous,
noncondensing, moisture environment. Condensing moisture
can cause a safety shutdown.

Vibration

Do not install the relay module where it could be subjected to
vibration in excess of 0.5G continuous maximum vibration.

Weather

The relay module is not designed to be weather tight. When
installed outdoors, protect the relay module in an approved
weather-tight enclosure.

Mounting Wiring Subbase

1. Mount the subbase in any position except horizontally

with the bifurcated contacts pointing down. The standard
vertical position is recommended. Any other position
decreases the maximum ambient temperature rating.

2. Select a location on a wall, burner or electrical panel.

The Q7800 can be mounted directly in the control
cabinet. Be sure to allow adequate clearance for
service, installation, access or removal of the
RM7838A, expanded annunciator, keyboard display
module, flame amplifier, flame amplifier signal voltage
probes, run/test switch, electrical signal voltage probes
and electrical field connections.

3. For surface mounting, use the back of the subbase as a

template to mark the four screw locations, then drill the
pilot holes.

4. Securely mount the subbase using four no. 6 screws

(not provided).

Wiring Subbase

CAUTION

Electrical Hazard.
Can cause electrical shock or equipment/
control damage.

Disconnect the power supply before beginning wiring.
More than one disconnect can be required.

1. For proper subbase wiring and sequence chart, see

Fig. 2.

2. For proper remote wiring of the keyboard display

module, refer to the Specifications for the keyboard
display module. (65-0090), network interface unit
(63-2278), Data ControlBus Module™ (65-0091) or
extension cable assembly (65-0131).

3. All wiring must comply with all applicable electrical

codes, ordinances and regulations. Wiring, where
required, must comply with NEC, Class 1 (Line Voltage)
wiring.

4. Recommended wire routing of leadwires:

a. Do not run high voltage ignition transformer wires

in the same conduit with the flame detector, Data
ControlBus Module™, or remote reset module
wiring.

b. Do not route flame detector, Data ControlBus

Module™ or remote reset module leadwires in
conduit with line voltage circuits.

c. Enclose flame detector leadwires without armor

cable in metal cable or conduit.

d. Follow directions in flame detector, Data

ControlBus Module™ or remote reset module
instructions.

66-1087—2

2

RM7838A 7800 SERIES RELAY MODULES

4

RESET
PUSHBUTTON

STATUS LEDs

BURNER
CONTROL

L1
(HOT)

CONFIGURATION
JUMPERS

SAFETY RELAY
CIRCUIT

1

120 Vac

50/60 Hz

FAN

3

MICROCOMPUTER

L2

RELAY
DRIVE
CIRCUIT

2K
3K
4K

5K
6K
7K
8K

9K

1K

POWER SUPPLY

PLUG-IN PURGE
TIMER CARD

FLAME SIGNAL

PLUG-IN
FLAME
AMPLIFIER

TEST

RELAY
STATUS
FEEDBACK
AND LINE
VOLTAGE
INPUTS

CONTROL
POWER

TEST
JACK

F

G

22

L2

6

RUNNING/
LOCKOUT

LIMITS

3K1

DDL

DDL
COMMUNICATIONS

PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED

1

S7800 INCLUDED WITH RM7838A.

2

COMBUSTION BLOWER OR EXHAUST RECIRCULATING FANS.

3

KEYBOARD
DISPLAY MODULE

INTERLOCK

HIGH FIRE SWITCH

19

RS485

1

2

REMOTE

3

RESET

1K1

7

2

5

1K1

2K1

7K1

2K2

5K1

8

10

21

9

3

LOW FIRE
SWITCH

ALARM
SILENCING
RELAY (DPST)

S445A
START

C

A

STOP

INDICATES FEEDBACK SENSING
OF RELAY CONTACT STATUS
AND LINE VOLT INPUTS

FIELD WIRING
INTERNAL WIRING

PILOT

D

IGNITION

B

MAIN VALVE(S)

ALARM

M5120C

Fig. 1. Internal block diagram of the RM7838A (see Fig. 2 for detailed wiring instructions).

3

66-1087—2

RM7838A 7800 SERIES RELAY MODULES

5. For recommended wire size and type, see Table 1.

6. For recommended grounding practices, see Table 2.

7. For keyboard display module (KDM). The KDM is

powered from a low voltage, energy-limited source.
It can be mounted outside of a control panel if it is
protected from mechanical damage.

NOTE: A 13 Vdc power supply must be used any

time more than one keyboard display
module is used. A maximum of two
keyboard display modules, Data ControlBus
Modules™ or S7810B Multi-Drop Switch
Modules are allowed in any combination.

9. Be sure loads do not exceed the terminal ratings. Refer

to the label on the RM7838A or to the terminal ratings
in Table 3.

10. The keyboard display module, Data ControlBus

Module™ (for remote mounting or communications) or

8. Maximum wire lengths:

a. RM7838A leadwires: The maximum leadwire

length is 300 feet (91 meters) to terminal inputs
(Control, Running Interlock, High Fire Switch and
Low Fire Switch).

b. Flame detector leadwires: The maximum flame

sensor leadwire length is limited by the flame
signal strength.

Communication Interface ControlBus Module must be
wired in a daisy chain configuration, (1(a)-1(a), 2(b)­2(b), 3(c)-3(c)). The order of interconnection of all the
devices listed above is not important. Be aware that
modules on the closest and farthest end of the daisy
chain configuration string require a 120 ohm (1/4 watt
minimum) resistor termination across terminals
1 and 2 of the electrical connectors for connections
over 100 feet (30.5m).

Table 1. Recommended Wire Size and Part Numbers.

Application Recommended Wire Size Recommended Part Numbers

Line voltage terminals 14, 16, or 18 AWG copper conductor,

600 volt insulation wire.

Keyboard Display Module 22 AWG two-wire twisted pair with ground,

or five-wire.

Data ControlBus Module™ 22 AWG two-wire twisted pair with ground,

or five-wire.

Remote Reset Module 22 AWG two-wire twisted pair, insulated for

low voltage.

Comunications Interface

22 AWG two-wire twisted pair with ground. Belden 8723 shielded cable or equivalent.

ControlBus™ Module
13 Vdc full wave rectified

transformer power input.

18 AWG wire insulated for votlages and
temperatures for given application.

c. Remote reset leadwires: The maximum length of

wire is 1000 feet (305 meters) to a remote reset
pushbutton.

d. Data ControlBus Module™: The maximum Data

ControlBus Module™ cable length depends on the
number of system modules connected, the noise
conditions and the cable used. The maximum
length of all Data ControlBus Module™
interconnecting wire is 4000 feet (1219 meters).

TTW60C, THW75C, THHN90C

Belden 8723 shielded cable or equivalent.

Belden 8723 shielded cable or equivalent.

—

TTW60C, THW75C, THHN90C

Table 2. Recommended Grounding Practices.

Ground type Recommended Practice

Earth ground (subbase and relay module). 1. Use to provide a connection between the subbase and the control

panel of the equipment. Earth ground must be capable of
conducting enough current to blow the 20A fuse (or breaker) in the
event of an internal short circuit.

2. Use wide straps or brackets to provide minimum length, maximum
surface area ground conductors. If a leadwire must be used, use
14 AWG copper wire.

3. Make sure that mechanically tightened joints along the ground path
are free of nonconductive coatings and protected against corrosion
on mating surfaces.

Signal ground (Keyboard Display Module,
Data Controlbus Module™, Communications
Interface ControlBus™ Module).

66-1087—2

Use the shield of the signal wire to ground the device to the signal
gorund terminals [3(c)] of each device. Connect the shield at both ends
of the daisy chain to earth ground.

4