Trane ReliaTel - Economizer Operation Enthalpy Changeover; Dry Bulb;Reference Point Selections; Comparative Enthalpy Method; Reference Enthalpy Method

104 RT-SVD03G-EN
Economizer Operation Enthalpy Changeover
Dry bulb/Reference Point Selections
The Dry Bulb or Reference Enthalpy Point is user-selectable, according to the choices below. This
selection is made on the ECA.
*factory setting
Comparative Enthalpy Method
OA Enthalpy is compared with RA Enthalpy.
• The Economizer is enabled when OA Enthalpy < [RA Enthalpy - 3.0 BTU/lb.]
• The Economizer is disabled when OA Enthalpy > RA Enthalpy.
• While [RA Enthalpy - 3.0 BTU/lb.] < OA Enthalpy < RA Enthalpy, the Economizer enable/disable
status is not changed.
Reference Enthalpy Method
OA Enthalpy is compared with a reference enthalpy point.
• The Economizer is enabled when OA Enthalpy < [reference enthalpy point - 0.5 BTU/lb.].
• The Economizer is disabled when OA Enthalpy > [reference enthalpy point + 0.5 BTU/lb.].
• While [reference enthalpy point - 0.5 BTU/lb.] < OA Enthalpy < [reference enthalpy point + 0.5
BTU/lb.], the Economizer enable/disable status is not changed.
Potentiometer
Setting Point
Dry bulb
changeover
Point
Reference
Enthalpy
A 73°F 27 BTU/lb
B 70°F 25 BTU/lb.
C* 67°F* 23 BTU/lb.
D 63°F 22 BTU/lb.
E 55ºF 19 BTU/lb
Figure 61. Comparative Enthalpy Enable
Economizer Enabled
Economizer Disabled
OA Enthalpy - RA Enthalpy
Comparative Enthalpy Hysteresis
Figure 62. Reference Enthalpy Enable
Economizer Enabled
Reference Enthalpy Hysteresis
OA Enthalpy - Ref Enthalpy (BTU/lb.)
Economizer Disabled