Supplemental Heat Lock Out - Lennox Prodigy M2 Application Manual

The first stage of supplemental electric heat is energized when defrost is initiated (default). In units with multiple refrigerant
circuits, supplemental electric heat is energized with each defrost circuit. (ECTO 1.14).
NOTE − If ECTO 1.14 is set to 0", there will be no supplemental heat during defrost.
Economizer dampers close during a defrost cycle.
3.6.4.

Supplemental Heat Lock Out

The M2 will not allow the delayed (K16 and K18) bank of electric heat to be energized if the outdoor temperature is above
30°F default (ECTO1.06).
The M2 will not allow any banks of electric heat to energize when outdoor air temperature is above 40°F default (ECTO
1.07).
3.6.5. Test Supplemental Electric Heat Operation
To test the operation of supplemental electric heat at outdoor temperatures above 40°F (default), turn on W2 input only
(emergency heat). See Testing Unit Function" section. Supplemental electric heat will be energized. To test supplemental
heat with compressor operating, disconnect outdoor air temperature sensor RT17.
3.6.6. Thermostats With Emergency Heat Function
When ONLY the W2 thermostat input is energized, the M2 will lock−out compressor operation and energize only electric heat.
Electric heat temperature lock−outs are also ignored.
3.7. Low Pressure Switches (S87, S88, S98, S97)
Low pressure switches may trip during lower outdoor temperatures, especially with longer time periods between compres-
sor cycling. Each compressor stage has the strike three control feature. The strike three control has three functions:
1. De-energizes the compressor for five minutes (default) if the low pressure switch trips (once the ignore time period is
elapsed).
2. Ignores the low pressure switch for a specified period of time after thermostat demand.
3. Locks out the compressor stage if the low pressure switch trips three times within the same thermostat demand (once
the ignore time period is elapsed).
3.7.1. Low Pressure Switch Off
Once the ignore time period has passed, the low pressure switch will de-energize the compressor. The M2 will prevent compres-
sor operation for five minutes. See ECTO parameter 5.02 to change compressor off time interval.
NOTE − Low pressure switches are ignored on heat pump units during heating.
3.7.2. Ignore or Shunt Time Period
The specified time period varies according to compressor off time and the outdoor ambient temperature. See chart below for
low pressure ignore default times and temperatures and the electronic configure to order (ECTO) parameter used to adjust
the ignore time period.
Ambient Temperature
ECTO 5 15 ECTO 5.15
3.7.3. Control De-Energizes Unit
If the low pressure switch trips three times (default) during a thermostat demand, the M2 will lock out the compressor. The
number of times required to de-energize the unit is adjustable. (ECTO 1.13, 4.15).
3.8. Loss of Power Detection (Single phase units only)
The M2 will turn off compressors for five minutes (default) if a loss of power is detected for two cycles. This indicates a problem
with supply voltage; waiting five minutes allows pressures to equalize ensuring start−up. (ECTO 5.02).
3.9. Thermostat Bounce Delay (Local thermostat mode only)
The M2 will ignore room thermostat inputs for three seconds to prevent sporadic cycling.
3.10. Return Air Temperature Limits
Zone temperatures may be limited by changing ECTO parameter 5.05. Change ECTO 5.06 to interrupt a heating demand
and ECTO 5.07 to interrupt a cooling demand. If return air temperatures are exceeded, the demand will be interrupted. Error
codes 40 or 41 are displayed but not stored in memory for recall.
3.10.1. Smoke Detector (A17−Optional)
If smoke detector senses smoke, normally opened contacts close. The M2 turns off the unit and closes the economizer
dampers. Variations in damper position and power exhaust and blower operation may be changed (ECTO 5.01). See table
7.
506457−01 05/10
Cold < 70º F
Hot > 70º F
Compressor Off Time ECTO 5.14
Short < 4 Hrs
5 Minutes ECTO 5.13
2 Minutes ECTO 5.12
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3. Unit Component Operation
Long > 4 Hrs
12 Minutes ECTO 5.11
6 Minutes ECTO 5.10