8
Control Systems Options
The MT series infrared heaters are available with a choice of
three different gas control options. The available controls and
associated control codes are (see Table 8.1 for description of
Control Codes):
• Direct spark ignition with 100% safety lockout with manual
reset
Natural Gas – Control Code 47 or 48
Propane Gas – Control Code 97 or 75
• Intermittent pilot ignition with non-100% shut-off
Natural Gas only – Control Code 08 or 04
• Millivolt, self-energizing with standing pilot and 100% safety
shutoff
Natural Gas – Control Code 27
Propane Gas – Control Code 67
Control Operating Sequence
Direct Spark Ignition Gas Controls – Control Codes
47, 48, 97, and 75
Utilizes a single-stage combination gas control, an ignition
control, and a single-stage thermostat.
1. The thermostat calls for heat.
2. The main gas valve opens and the spark igniter sparks in
an attempt to light the gas at the ceramic burner.
3. Once the burner is lit, the flame sensor proves ignition and
stops the spark igniter from sparking. If ignition is not
proven (the burner does not light) within 15 seconds, the
system will lockout, de-energizing the gas valve and ignition
control system. If the system locks out, it may be reset by
an interruption of the power source. The system will then
attempt to light the burner, if a call for heat from the
thermostat remains.
4. The unit continues to operate until the thermostat is
satisfied, at which time the main gas valve closes 100%
and the unit shuts off.
Intermittent Pilot Ignition with Non-100% Shut-Off
Gas Controls – Control Codes 08 and 04
Utilizes a single-stage combination gas control, an ignition
control, and a single-stage thermostat.
1. The thermostat calls for heat.
2. The pilot gas valve opens and the pilot spark igniter sparks
in an attempt to light the pilot.
3. The pilot flame sensor attempts to prove pilot ignition. If the
pilot does not light, ignition sparking and pilot gas flow will
continue until the pilot flame is established.
4. Once the pilot is lit, the pilot flame sensor proves ignition
and stops the spark igniter from sparking. At the same time
the main gas valve is opened and the ceramic burner is lit.
The unit continues to operate until the thermostat is
satisfied, at which time the main gas and pilot gas valves
are closed 100% and the unit shuts off.
Millivolt, Self-Energizing with Standing Pilot and
100% Safety Shutoff Gas Controls – Control Codes
26 and 67
Utilizes a single-stage combination gas control and a single-
stage millivolt thermostat.
1. The pilot is manually lighted with the gas valve control knob
depressed in the PILOT position and held (approximately 1
minute) until the millivolt generator is heated sufficiently to
keep the pilot valve open. The control knob is then turned
to the ON position.
2. Upon a call for heat, the millivolt thermostat contacts close,
completing the circuit to the gas valve. The gas valve will
open and the ceramic burner is lit from the standing pilot.
3. Once the millivolt thermostat is satisfied, the main gas valve
closes 100% and the unit shuts off, with the pilot valve
remaining open with a standing pilot.
4. If the pilot goes out, the millivolt generator will cool and
interrupt the circuit to the pilot valve. Both the pilot and
main gas valves are closed 100%. The unit remains
inactive until step 1 is repeated.
START-UP PROCEDURE
Table 8.1
Performance and Available Control Systems
➀ ➁
➀
Model MT high intensity infrared heaters with direct spark or intermittent pilot ignition are equipped with 25 volt controls.
➁
Control codes specified for line voltage supply include 115V/25V step-down transformers.
Direct Spark Ignition of Burner
➀
Intermittent Pilot
➀
Millivolt, Self Energizing
100% Safety Lockout with Manual Reset
Non 100% Shut Off
Standing Pilot, 100% Safety Shut Off
Control Code
- Supply/Thermostat Voltage
Control Code
- Supply/Thermostat Voltage
Control Code
- Thermostat Voltage
Natural Gas
Propane Gas
Natural Gas
Natural Gas
Propane Gas
Model No. 47
- 115V
➁
48
- 25V
97
- 115V
➁
75
- 25V
08
- 115V
➁
04
- 25V
27
- Millivolt
67
- Millivolt
MT-28
•
•
N/A
N/A
•
•
•
N/A
MT-30
•
•
•
•
•
•
•
•
MT-33
•
•
N/A
N/A
•
•
•
N/A
MT-56
•
•
N/A
N/A
•
•
•
N/A
MT-60
•
•
•
•
•
•
•
•
MT-66
•
•
N/A
N/A
•
•
•
N/A
MT-84
•
•
N/A
N/A
•
•
•
N/A
MT-90
•
•
•
•
•
•
•
•
MT-99
•
•
N/A
N/A
•
•
•
N/A
MT-112
•
•
N/A
N/A
•
•
•
N/A
MT-120
•
•
•
•
•
•
•
•
MT-132
•
•
N/A
N/A
•
•
•
N/A
MT-160
•
•
•
•
N/A
N/A
N/A
N/A