A
M-TRAC1
IOM-55
May 2019
19
HEAT OPERATION FLOWCHART
- Close heat switch and/or any other contacts or interlocks to power terminal
HS (24Vac).
- If system is reverse interlock the AL output will have closed when the supply
fan successfully started, and enabled the exhaust fan.
- Light D slow blink should now be Off.
Light B
irregular
blink?
Light B slow
blink?
Light B fast
blink?
Light B on?
- Wiring or flame relay problem. Check wiring into
terminals VFB120 and VN safety inputs.
- High limit safety contact is open. M-TRAC is
expecting 120Vac to terminal LMT.
- 16 second prepurge (DIP #6 on) or delay to set
modulating valve to ignition position.
No
Yes
Yes
Yes
Yes
No
No
No
- FR and CFR contacts close.
- PV1 and PV2 contacts close.
- Ignition control enabled.
Ignition sequence:
- Ignition control enables pilot valve and sparks at electrode.
- Pilot flame achieved and sensed.
- Ignition control outputs power to main valve control relay.
- Relay contact close to enable main valve(s) (SSOV).
- 120V feedback signal into terminals VFB120 and VN from main valve(s).
- Main burner lit from pilot flame.
- Ignition spark off.
- PV1 and PV2 contacts delay off to disable pilot valve. Ignition control is sensing
main burner only.
- Light D on (burner on).
End of heat section.
- Burner modulating valve enabled to
maintain discharge air temperature
setpoint, from 0-10Vdc output terminal
HD.
