Rtem W/ Rtrm V7.0 And Earlier - Trane ReliaTel Diagnostic Manual

During normal occupied mode, if the unit is not actually heating or cooling, and the fan switch is
set to auto, the supply fan will be off. If the unit is configured for Active DCV control (DCV Mode
OPEN), the supply fan will be energized when the space CO
Setpoint and the DCV algorithm will be in control of the outdoor air damper position. When the
space CO
close the damper to the DCV Min Position Setpoint. Once the space CO
Limit CO
will de-energize if not requested ON by another function.
The RTEM allows the selection of either Active or Passive DCV control. Installing a jumper across
J10-1 and J10-2 on the RTEM module configures the unit for Passive DCV control. When configured
for Passive DCV control, DCV control is not allowed to force on the supply fan, and DCV control will
only be allowed when the supply fan is on (commanded ON by another function, such as comfort
heating or cooling control, or the supply fan mode set to ON). Passive DCV will operate identically
to Active DCV once the Supply Fan is energized.
Important: While the ReliaTel will allow Active DCV control when the fan mode is set to AUTO

RTEM w/ RTRM v7.0 and Earlier

For units equipped with an RTRM v7.0 or earlier and also an RTEM, the control will utilize a single
CO
Setpoint Selection
Units equipped with an RTRM v7.0 or earlier will utilize a single CO
this setpoint and space CO
between the Bldg Design Min Position and DCV Min Position Setpoints.
For DCV control in these units, the CO
Design Min Position will be set using the onboard potentiometer which will have a range of 10 to
50% and the DCV Min Position will be set using the onboard potentiometer which will have a range
of 0 to 40%. This scheme enforces a 10% differential between the Bldg Design Min Position and the
DCV Min Position Setpoints.
Sequence of Operation
For units equipped with RTRM v7.0 or earlier and an RTEM, only Active DCV control is available,
as the DCV Mode Configuration input is not recognized prior to RTRM v8.0.
Supply Fan Mode = ON
When the unit is in the occupied mode, the outdoor-air (OA) damper opens to the DCV Min Position
Setpoint. If the space CO
Design Min Position Setpoint. If the space CO
50 ppm below the setpoint, the OA damper will stop modulating (holding its current position). If
the space CO
DCV Min Position Setpoint. If there is a call for economizer cooling, the outdoor air damper may
be opened further to satisfy the cooling request.
Supply Fan Mode = AUTO (from Zone Sensor or all T-stat inputs inactive)
When the supply fan is energized (commanded ON by another function, such as comfort heating
or cooling control), DCV control will operate as described above ("Supply Fan Mode = ON").
When the supply fan is de-energized, if the space CO
control will energize the supply fan and open the OA damper to the Design Min Position Setpoint.
RT-SVD03G-EN
CO Sensor Connections (ReliaTel Units with Demand Controlled Ventilation)
2
level falls below the Lower Limit CO
2
Setpoint minus 50 ppm and the OA damper is at the DCV Min Position the Supply Fan
2
(cycle on and off with the compressor or heater), this practice is discouraged
because it can result in excessive fan cycling and may not comply with ASHRAE
Standard 62.1. If CO
(operate whenever the zone is occupied) or the unit should be configured for Passive
DCV control.
Setpoint and two separate Damper Minimum Position Setpoints as described below:
2
level rises above the CO
2
level drops below the CO
2
Setpoint minus 50 ppm, DCV control will begin to
2
-based DCV is used, the supply fan mode should be set to ON
2
input value to determine the active OA damper position setpoint
2
Setpoint will have a range of 500 to 1500 ppm. The Bldg
2
2
level drops below the CO
2
Setpoint minus 50 ppm, the OA damper will close to the
2
level rises above the Lower Limit CO
2
level is below the Lower
2
Setpoint. The RTEM will use
2
Setpoint, the OA damper will open to the Bldg
Setpoint, but is not yet
2
level rises above the CO2 Setpoint, DCV
2
2
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