Do not install the relay module where it could be subjected
to vibration in excess of 0.5G continuous maximum
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 horizon-
tally with the bifurcated contacts pointing down. The
standard vertical position is recommended. Any
other position decreases the maximum ambient
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 ser-
vice, 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
NOTE: You might receive an error code 101 (via KDM) if
one of the following conditions exist:
a. The screws securing the relay to the subbase are
not tight enough, re-tighten to insure there is no
gap between the relay and the subbase.
b. If you attempt to place a 2000 series relay on a
non-compatible 1000 series subbase, this indi-
cates that you must:
• Change out the subbase to a Q7800A2003/U
• Choose a compatible 1000 series relay
Relay Module and Subbase
NOTE: There are several different subbase models that
can be purchased. It is important to note which
subbase is compatible with the relay module
when purchasing new, repair or replacement
Series 1000 Relay Modules
All relay product codes that start with a 1 (example:
EC7820A1026/U) can be used with existing subbase
Q7800A1003/U and Q7800A1005/U.
Series 2000 Relay Modules
All relay product codes that start with a 2 (example:
EC7820A2026/U) must be used with subbase
Q7800A2003/U and Q7800A2005/U.
Any Relay Module in the 1000 Series with a Software
Revision level number starting with a "5" or greater will be
compatible with all subbase models both installed and
newly purchased. This includes (Q7800A1005/U,
Q7800B1003/U), and the 2000 Series subbases
See Fig. 1 for Software Revision Level number location on
the label (located on the rear of the relay module).
Any relay module in the new 2000 series will only be able
to be installed on subbase Q7800A2005/U,
Q7800B2003/U and will not be backward compatible with
any Q7800A1003/U and Q7800A1005/U subbases
already installed in the field.
Fig. 1. Software revision location.
Make sure to check the relay model number and
the software revision level on the relay.
If you attempt to place a 2000 series relay on a non-
compatible 1000 series subbase, you will receive an error
code of 101. This indicates that you must a) change out the
subbase to a Q7800A2003/U or Q7800A2005/U or b)
choose a compatible 1000 series relay module.
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
2. For proper remote wiring of the KDM, refer to the
Specifications for the 2-line VDF KDM (65-0090),
the 4-line LCD KDM (32-00110), Data ControlBus
Module™ (65-0091) or Extension Cable Assembly
3. All wiring must comply with all applicable electrical
codes, ordinances and regulations. Wiring, where
required, must comply with NEC, Class 1 (Line Volt-
4. Recommended wire routing of leadwires:
c. Do not run high voltage ignition transformer
wires in the same conduit with the flame detec-
tor, Data ControlBus Module™, or remote reset
7800 SERIES RELAY MODULES