EDGE-1830 / EDGE-2440 / EDGE-3240 / EDGE-2460 / EDGE-3260 / EDGE-3860 / EDGE-4460 / EDGE-3270
Original Service Manual
12
Rev 2.1, January 2021
❖
iHeat is Active, begins system test
✓
iHeat spins up the induction blower and verifies TACH feedback (absence of TACH
results in brief Blower full ON state and a failed verification (not within ±10% of expected
TACH feedback)
✓
iHeat verifies 4-20mA control signal from the control system (must be > 2mA)
✓
iHeat performs self-check on the VALVE output (square wave detection)
✓
iHeat begins 30s pre-purge timer, following which, iHeat begins Run Cycle
❖
iHeat control ignition/run cycle (1)
✓
Pre-purge period expires, iHeat RELAY N.O./COM contacts are closed, passing 24VAC
✓
24VAC from RELAY N.O. supplies Ignition Module (FS/SI) and Optical Detector (FS)
✓
iHeat valve output (0-10VDC) and MOTOR L/N output to induction blower are modulated
according to control signal
❖
Ignition Module Operation
✓
FS/SI performs verifi
cation of “No Flame” prior to ignition trial
✓
FS/SI sends 24VAC from valve output to Honeywell valve cable (output of cable is 24VDC)
✓
FS/SI excites electrodes for a period of 4s
✓
If flame is detected, valve output remains powered, system is now in normal operation mode
✓
If flame is not detected, 30s inter-purge delay followed by 2
nd
trial, lock-out after 3
rd
trial (112s)
❖
iHeat control ignition/run cycle (2)
, “Recovery ON/OFF”
✓
iHeat modulates induction motor and valve according to control signal
✓
If control signal reaches and maintains 4mA for 45 seconds, an over-temperature situation
is presumed: RELAY N.O. will open, deenergizing the ignition system until control loop signal
is above 10.2mA *(gas pressure out of adjustment) **
STAGE 1 OTP
✓
If control signal falls below 2mA, RELAY N.O. will open until power cycle occurs *(lost control
signal)
✓
If Blower Motor TACH signal falls ±10% of expected, RELAY N.O. will open until power cycle
occurs
❖
High limit prevention **STAGE 2 OTP
The high limit prevention circuit will shut down the combustion system (P9.3) if the bake chamber
temperature exceeds 650°F / 343
°
C. This will also occur if the thermocouple is disconnected or has a
break.
**STAGE 3 OTP
, a 700
°
F / 371
°
C Manual Reset Thermostatic switch is installed in the back of
the oven. This thermostatic switch, when opened, will remove power from the combustion system.
❖
Cool down
When the bake chamber temperature exceeds 225°F / 107°C, the cool down circuit will be triggered.
Relay K1 (P10.1) will be held ON until the temperature falls to 223°F / 106°C. During this time, the
Oven Control will display the temperature, Cool Down Icon, and a Power Icon. The cooling fan and
Main Motor fan will remain ON during the cool down process.
Before performing any service tasks on the oven, be sure the power and gas supply have been
disconnected.
Always make good notes and take photos to ensure correct re-assembly.
