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RT-SVD03L-EN
ReliaTel
™
™
Hot Surface Ignition Control
12.5 to 50 Tons, 1 Stage, 2 Stage,
and Modulating Gas Heat
This microprocessor based, communicating solid state
device provides gas valve control, proof of ignition,
ignition retries, one hour reset, operation of the inducer
and diagnostics through an LED, as well as
communication to the RTRM via a MODBUS
communication link. Inputs to the control include high
limits and flame sensor operation. A combustion fan
proving switch is used with modulating gas heat units
but is not used with 1 or 2 stage burners. This device
takes control of the ignition, timings related to the
ignition cycle and supervision of the gas components.
Table 89.
Ignition module specifications
Voltage range
18-32 vac, 50/60 Hz
Ignitor voltage
115vac, 50/60 Hz
Flame sense current
4.5 microamps (nominal), 1
microamp minimum
Pre-purge
45 sec
Flame establishment
period
2 sec min, 7 sec max
Flame failure response
time
0.8 sec or less
Loss of flame lockout
3 tries, locks out after 3rd try
Lockout reset
Interrupt power for 3 seconds
minimum
Auto reset
1 hour
Loss of communication
lockout(with RTRM)
10 sec
Ignition Control Module
Diagnostics
There is a green LED located on the ignition module.
The table below lists the diagnostics and the status of
the LED during the various operating states.
Any time the Ignition module is powered, the LED will
be lit to provide status of the ignition system. At initial
power-up, the LED will flash for one second.
The pause between groups of flashes is approximately
two seconds.
Modbus voltage (measure between RTRM J5-3 and J5-
4):
•
With J5 plug connected, will read approximately 9.6
to 10.7 vdc (Flashing)
•
With J5 unplugged, will read approximately 10.5 to
11.2 vdc (Flashing).
Table 90.
Ignition module diagnostics
Steady OFF
No power/ Internal failure
Steady ON
Normal power-up, with no heat call.
Slow flash rate
Normal call for heat, ¾ second on, ¼ second
off.
Fast flash rate
Used for error indication only
One flash
Communication loss between RTRM and IGN
Two flashes
System lockout; failed to detect or sustain
flame
Three flashes
Not used
Four flashes
High limit switch open
Five flashes
Flame sensed and gas valve not energized; or
flame sensed and no call for heat
Sequence of Operations (1 and 2
heat units)
The 12.5-through 50-ton packaged units use a drum
and tube heat exchanger with a negative pressure gas
valve and hot surface ignition. This design is the same
as was used with the UCP micro controls, but the
control circuitry for ignitions has changed to take
advantage of ReliaTel
™
MODBUS communications.
When the system switch is set to the "Heat" position
and the zone temperature falls below the heating
setpoint, a heat cycle is initiated when the RTRM
communicates ignition information to the ignition
module (IGN).
The IGN runs a self-check (including verification that
the gas valve is de-energize). IGN checks the high-limit
switches (TC01 & TCO2) for normally closed contacts.
With 115 vac supplied to the ignition module (IGN), the
hot surface ignitor probe (IP) is preheated for
approximately 45 seconds. The gas valve (GV) is
energized for approximately 7 seconds for trial ignition
to ignite the burner.
Once the burner is ignited, the hot surface ignition
probe (IP) is de-energized by the ignition module and
then functions as the flame sensor. The unit initially
fires on high heat, but after approximately 60 seconds,
if no additional heating is required, the ignition module
will drop back to low heat.
When the fan selection switch is set to the "AUTO"
position, the RTRM energizes the indoor fan relay (F)
approximately 45 seconds after initiating the heating
cycle to start the indoor fan motor (IDM).
If the burner fails to ignite, the ignition module will
attempt two more ignition cycles before locking out.
The green LED will indicate a lockout by two fast
flashes. An ignition lockout can be reset by:
Summary of Contents for ReliaTel
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