Low Ambient Operation - York eco2 050 Installation Operation & Maintenance

Sequence of Operation
Sensor
If all conditions are met, the control will look for an
attached IAQ sensor at the appropriate AI 4. The read-
ing at the AI 4 will be used along with the "IAQ Sen-
sor Span" setting to determine the building CO
The sensor must be supplied in the Þ eld and the "IAQ
Sensor Span" will vary based on the manufacturer and
type of sensor.
If the CO level indicated at the AI is out of range, the
2
controller will interpret the reading as a sensor failure
and generate a Trouble Fault. Demand Ventilation con-
trol sequences will not be allowed if the CO
de ter mined to be unreliable.
Algorithm
An appropriate algorithm is used for Demand Ven ti -
la tion control. A step and wait algorithm with the fol-
low ing characteristics is used:
• Step size is a function of the dif fer ence be tween
the measured IAQ (CO2) level and the De mand
Ventilation Setpoint.
• Step time is Þ xed.
The Demand Ventilation operation will have the fol-
low ing constraints:
70
The maximum OA Damper position called for by De-
mand Ventilation operation will be equal to the ("Max
DV Multiplier") * ("OA Damper Min Pos #1"). The
"Max DV Multiplier" parameter can be set for a mini-
mum of 1, which results in a damper position the same
level.
as the minimum position, to 4, which results in a damper
2
position 4 times the minimum position.

LOW AMBIENT OPERATION

With the standard unit, mechanical refrigeration will
only be allowed to operate when the ambient tem per a ture
is above the "Cool Lockout OAT" setting. Be low
sensor is
2
this tem per a ture, compressors will be inhibited from
operating.
Optional hardware can be installed on one or more
com pres sor systems that will allow me chan i cal re frig -
er a tion to occur below the Cool Lockout OAT Set point.
The hardware for each Low Am bi ent con Þ g ured sys-
tem consists of a Condensing Pres sure trans duc er on
the refrigerant circuit and a Vari able Speed Drive that
varies the speed of one con dens er fan to con trol the
Condensing Pres sure in side the con dens er coil. The
second condenser fan for the system is op er at ed on/off
through di rect con trol by the com pres sor sys tem. The
following Þ gure il lus trates the equip ment re quired for
low am bi ent operation.
FORM 100.50-NOM1 (604)
YORK INTERNATIONAL