22
OMM 1008-1
20 ma
(54.0°F)
Cool LWT Set-Point
(44.0°F)
4 ma
LWT Reset (Cool mode)
(temperatures are examples only)
0 ma
Max Reset Delta T
(10.0°F)
1.
Cool LWT setpoint
2.
Max Reset Delta T setpoint
3.
Start Reset Delta T setpoint
Reset is accomplished by changing the Active Leaving Water variable from the (Cool LWT setpoint) to the
(Cool LWT se Max Reset Delta T setpoint) when the evaporator (return – leaving) water temperature
delta varies from the (Start Reset Delta T setpoint) to 0.
The Active Leaving Water variable is set equal to the Cool LWT setpoint if the reset signal is less than or
equal to 4 mA. It is set equal to (Cool LWT se Max Reset Delta T setpoint) if the reset signal equals
or exceeds 20 mA. The Active Leaving Water variable will vary linearly between these extremes if the reset
signal is between 4 mA and 20 mA. An example of this action is shown below.
