Copyright © 1998 Honeywell Inc. • All Rights Reserved
X-XX UL
INSTALLATION INSTRUCTIONS
S8921D
Hot Surface Ignition Module
APPLICATION
The S8921D Hot Surface Ignition Module controls the
operation of an LP or natural gas fired direct ignition
heating appliance that includes a combustion air blower
and an air proving switch. The S8921D ignites the main
burner with a 120 Vac hot surface igniter (Norton 271 or
equivalent). A flame rectification safety circuit monitors
the main flame through a remote flame sense rod. The
system provides up to five trials for ignition before
lockout if the appliance fails to light or loses flame during
the heating cycle. An automatic recycle feature initiates a
new ignition trial if the call for heat remains for one hour
after lockout due to failure to light.
Because it has a special operating sequence that limits
the time that the combustion air blower is energized
when the appliance is not delivering heat, the S8921D is
well suited for agricultural and other applications where
cold air flow into the heated space is highly undesirable.
SPECIFICATIONS
Electrical Ratings:
Control Voltage: 24V, 60 Hz.
Valve Contact Rating: 2A.
Current Draw: .4A plus valve load.
Line Voltage: 120 Vac, 60 Hz.
Contact Rating at 120 Vac.
Hot Surface Igniter: 5A.
Combustion Air Blower: 3 FLA, 10 LRA.
IMPORTANT:
The S8921D is to be used only in a 60 Hz
system. Be sure the system is not 50 Hz.
Hot Surface Igniter:
Norton Model 271 or equivalent.
NOTE:
If an igniter other than a Norton Model 271 is
used, the igniter must meet the following
minimum specifications required over the life of
the igniter:
—
Igniter must reach 1832
°
F (1000
°
C) within
17 seconds with 102 Vac applied.
—
Igniter must maintain at least 500M ohm
insulation resistance between the igniter
leadwires and the igniter mounting bracket.
—
Igniter must not develop an insulating layer
on its surface (over time) that would
prevent flame sensing.
—
Igniter surface area immersed in flame
must not exceed one-fourth of the
grounded area immersed in flame. This
would prevent flame sensing.
—
Igniter current draw at 132 Vac must not
exceed 5A.
Flame Sensor:
Separate sensor required.
Air Proving Switch:
SPNO air proving switch required.
Prepurge:
0 seconds.
Igniter Warmup:
17 seconds (first trial).
27 seconds (second through fifth trials).
Ignition Trial:
7 seconds.
Ignition Activation Period:
4 seconds.
Between Trial Delay:
0 seconds.
Flame Failure Response Time:
Less than 0.8 second at 1 uA flame signal.
Flame Current:
0.8 uA dc minimum.
Ambient Operating Temperature:
-40
°
F to +175
°
F (-40
°
C to +79
°
C).
Approvals:
International Approval Services (IAS) Design Certified:
Report No. C2030018.
69-0924-2