Return Water Reset - Daikin EWWQ-AJYNN Service Manual

Functional Control
2.5

Return Water Reset

1
Introduction
2
Function
description
3
4
5
Explanation
2–56
When return water is selected as the reset mode, the MicroTech controller will adjust the leaving
chilled water setpoint to maintain a constant return water temperature equal to the return water
setpoint. The return water temperature is sampled every 5 minutes and a proportional correction is
made to the leaving chilled water setpoint. The corrected leaving water setpoint is never set to a value
greater than the return water setpoint and is never set to a value less than the actual leaving chilled
water setpoint.
Actual Setpoint
Max
reset
Local or Dual
Setpoint
chLWT Return Reset
Start dT
Max Reset
Remark: When the unit is designed for a ∆T of 5°C (at 100% capacity), then the start ∆T and Max
Reset should also be set to 5°C.
The return water reset will adjust the leaving chilled water setpoint according to the evaporator ∆T. In
this way the chiller can maintain a constant return water temperature.
0 start
∆T
3 ˚C
3 ˚C
ESIE07-05
∆T on evaporator
Part 2 – Functional Description