Operating Mode Selection; Compressor Frequency Calculation; Cooling Mode; Heating Mode - Carrier 30AWH004HB Service Manual

Operating mode selection

The operating mode is selected based on the command chosen by the remote control.

Cooling Mode

Depending by the system configuration and when the operating mode is cool, the system could operate as follows:
With Comfort NUI (CS1).
With SUI (RC1) / Dry inputs.
The WSP (Water Set Point) will be defined as follow:
- Fixed WSP: as per the appropriate variable value (Standard and Eco)
- Climatic Curve depending by OAT (see the controls manuals and the paragraph 7.3.5 )
For more information about the cooling mode logics used to determine the WSP, refers to the SUI or NUI manuals.

Heating Mode

Depending by the system configuration and when the operating mode is Heat, the system could operate as follows:
With Confort NUI (CS1).
With SUI (RC!) / Dry inputs
The WSP will be defined as follow:
- Fixed WSP: as per the appropriate variable value (Standard and Eco)
- Climatic Curve depending by OAT (see the controls manuals and the paragraph 7.3.5 )
Off Mode
If the Operating Mode is OFF then:
- All outputs must be de-energized except those turn on by protections.
- Send Forced OFF Message to the unit
- Water pump is de-energized AFTER 30 SEC.
- Antifreeze and all protections algorithms will be always operative
- Sanitary Hot Water management in OFF mode is based on code 153 (1: always active 2: active only in HTG or CLG
mode)
In case of User Interface is Simple User Interface (dry contacts). The code 100 must be 0 or 1 & code 101 must be 0.
Cooling mode and in SHW demand. Every time the compressor turns on a timer restarts to count the Compressor Run
Time (CRT).
- If CRT < 18 minutes the compressor frequency is progressively reduced from the current to the
minimum value until CRT >18 minutes.

Compressor Frequency Calculation

- When the Frequency reduction mode is activated through the NUI Bus, RS 485 bus or Limitation Frequency Input, the
max compressor frequency
- When the Unit Mode is OFF, the unit operates in cool/heat satisfied mode with a compressor frequency of zero, F(n) =0.
Calculating Frequency
The calculated water temperature exiting exchanger and calculated set point are continuously monitored. The frequency
is calculated on the values of LWT and WSP. If the leaving water temperature changes causing a positive delta or if the
calculated set point changes, a normal demand calculation is performed every 90 seconds (60 in heat mode). Now the
frequency is calculated on the values of E(n) and ΔE(n).
Demand vs. Satisfied
max (Fhmin, F(n)) ) , and demand calculations execute every 90 (60 in Heat mode)
seconds.
- When the compressor is on send the Cool/Heat Demand message to the unit.
Water pump is always energized
SM_30AW.indd 58
Control management
58
5
OAT: Outdoor
Air
Temperature
WSP: Water Set Point
LWT: Leaving water
temperature
WSP:
calculated water
set point
F(n): frequency
sent to the
unit, clamped
between zero
and Fcmax
E(n)=LWT- WSP
ΔE(n): E(n-1)-E(n)
Fcmax:
maximum com-
pressor
speed allowed
in cooling
Fcmin:
minimum
compressor
speed allowed
in cooling
Fhmax:
maximum
compressor
speed allowed
in heating
Fhmin:
minimum
compressor
speed allowed
in heating
30AW
14-03-2011 14:45:05