Table of Contents
Advertisement
3. Unit Component Operation
3.1.
Compressor Protection and Delays
NOTE - If parameter 89 is set with a minimum off delay and there is a new demand, the M3 unit controller display will
indicate the demand is active (i.e., cooling). However, the compressor(s) will not come on until the delay time has been
specified has been met.
3.1.1.
Compressor Minimum Run-Time and Off-Delay
3.1.1.1.
All Energence LC/LG Ultra-High Efficiency Units
Energence UltraHigh Efficiency Units have both compressor Minimum Run-Time (default 240 seconds) and Minimum
Off-Delay (default 300 seconds) and is always enabled. This method cannot be altered, however parameter time settings
can be adjusted.
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 91 (COMP MIN RUN TIME)
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 89 (COMP MIN OFF DELAY)
3.1.1.2.
All Other Energence Models
On all other Energence models, Minimum OFF Time is enabled by default while Minimum Run Time is disabled by
default.
This method can be altered by modifying parameter 225 but can only be modified using the Lennox unit controller
Software (UCS).
Selecting the UNIT_OPERATION_DISABLE_SLUG_2_0' option will enable Minimum Run Time (parameter 91) and
disable the Minimum OFF Time (parameter 89) protection for 3-phase systems only.
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 91 (COMP MIN RUN TIME)
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 89 (COMP MIN OFF DELAY)
NOTE: For units with multiple compressors, compressors will remain off for a user specified duration (parameter 89),
when the last running compressor is turned off due to completion of demand or a fault that cause both compressors to be
shut down.
3.1.2.
Compressor On Delay
On Energence models 036H, 048H and 060H the fan will start a few second before starting the compressor. The time
delay is fixed and cannot be altered.
On Energence high efficiency 3 to 5 ton units (with ECM outdoor fan only) the low stage compressor on delay is set for 11
seconds. This will allow the outdoor fan to come up to full speed for at least five seconds before the compressor starts.
During this delay, the M3 unit controller will display on the screen (DELAY UP TO 20 SEC).
3.1.3.
Freeze-stats (S49, S50, S53 and S95)
Normally closed freeze-stat switches will open when the evaporator coil temperature drops to de-energize the
corresponding compressor or tandem compressors. Once coil temperature rises the switch automatically resets to allow
compressor operation. The corresponding compressor or tandem compressors are locked out after three occurrences
(default) during a single demand cycle (mechanical cooling only) which is set using parameter 81. The adjustable range is
1 to 3 occurrences.
When a compressor is de-energized due to an open freeze-stat switch, alarm 32 (S49 switch), 34 (S50 switch), 36 (S53
switch) or 38 (S95 switch) is issued.
NOTE: No alarms are recorded during free cooling or off cycles between cooling calls. In addition, even if parameter 81 is
set to an alternate occurrence number, the alarm itself will always indicate three strikes.
NOTE: Freeze-stat alarms will not indicate an OFF ON ALARM state (see table 61).
The corresponding compressor is locked out after three occurrences (default) which is set using parameter 81.
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 81 (MAX FREEZE STAT OCC)
3.1.4.
Thermal Protection Switches (S5, S7, S8, S31 and S180)
NOTE: Not all models use all of the reference switches. Verify with unit wiring diagram to confirm switch(es) used. Also
refer the unit installation instruction for switches used and operation.
Thermal protection switches open on a temperature rise to de-energize the corresponding compressor. Switches
automatically reset when temperature drops.
The corresponding compressor is locked out after three occurrences (default) of either high pressure or high temperature
conditions during a demand cycle. The number of occurrences can be changed using for parameter 98. Adjustable range
is 1 to 7 occurrences.
16
Hide quick links:
Advertisement
Table of Contents
