Trane Tracer VV550 Installation, Operation And Maintenance Manual page 54

Sequence of Operations
CO2-based demand-control ventilation procedure
CO
controller cannot monitor CO
space CO
demand ventilation rate of the zone. The resulting ventilation rate is called the effective
ventilation setpoint. The effective ventilation setpoint is the outdoor airflow required to
provide ventilation. It is used to calculate the ventilation ratio of the zone.
outlines the derivation of the outdoor air requirement.
Table 36.Calculation of reported effective ventilation setpoint for CO
Communicated space CO
Less than configured space
CO low limit
2
More than configured space
CO high limit
2
Configured space CO low
2
limit  communicated space
CO  configured space CO
2
high limit
a. If the value of the communicated ventilation setpoint is valid, it is used but it is limited by the configuration: Configured
standby-ventilation setpoint  Communicated ventilation setpoint  Configured ventilation setpoint.
b. Reported effective ventilation setpoint = Configured standby-ventilation setpoint + (Communicated space CO
space CO low limit) * Communicated ventilation setpoint limited by configuration: Configured standby-ventilation setpoint ÷
2
(Configured space CO
2
The communicated space CO
limit and the configured space CO
must fall between the configured ventilation setpoint and the configured standby-
ventilation setpoint. If the configured space CO
configured space CO
configured standby-ventilation setpoint.
54
-based demand-control ventilation uses the communicated space CO
2
concentration to the configured band of CO
2
Reported effective
ventilation
setpoint
2
Configured standby-
ventilation setpoint
Communicated
ventilation setpoint
limited by
a
configuration
Linear modulation
between configured
standby-ventilation
2
setpoint and
communicated
ventilation setpoint
limited by
a
configuration
high limit – configured space CO
low limit, the reported effective ventilation setpoint is equal to the
2
from a local CO sensor. The controller compares the
2 2
-based DCV zones
2
Description
Zone CO concentration is low. Zone is most likely unoccupied.
2
Contaminants come from the zone itself (carpet, furniture, paint,
etc.). A minimum of ventilation air is required to ventilate the
zone.
Zone CO concentration is high. Zone is most likely at maximum
2
designed occupancy. Contaminants come from people and
building sources. A maximum of ventilation air is required to
ventilate the zone.
Zone CO concentration is mid-range. Zone is most likely at partial
2
occupancy. Contaminants come from people and building sources.
However, zone is not at maximum design occupancy and does not
need maximum design ventilation.
low limit).
2
value must fall between the configured space CO
2
low limit. The reported effective ventilation setpoint
2
high limit is less than or equal to the
2
value. The
2
values and determines the
2
Table 36
b
– Configured
2
CNT-SVX17G-EN
high
2