High Temperature Protection; Anti Frost Protection; A/C Power Interruption; Envelope Limitation Protection - Carrier 30AWH004HB Service Manual

High Temperature Protection

When the water starts to get to hot, this is a sign that the pressure in the system is increasing.
Certain actions are taken to decrease the pressure.
While in Zone N or L the frequency can't increase.
While in Zone M the frequency is forced to decrease until Fcmin.

Anti frost protection

This function shall run when the unit is manually stopped or shutdown due to alarm. It shall protect the water exchanger
against freezing risk because of low outside temperature conditions.
The following logic shall be used:
o Trace Heater (first intervention) (when installed).
o Water Pump (second intervention)
Threshold A
Threshold B
Threshold C
Threshold D

A/C Power Interruption

This algorithm handles the case of losing A/C line cycles.
cool satisfied or heat satisfied until time guard expires.

Envelope Limitation Protection

This function limits frequency based on a combination of OAT and LWT, in order to guarantee the unit envelope. The
HEATING
-20 °C ≤OAT≤30 °C
20 °C≤LWT≤60 °C
COOLING
0 °C ≤ OAT ≤ 46 °C
4 °C ≤ LWT ≤ 18 °C
For more details see par 2.4 Operation Limits
When the OAT and/or LWT values are out of these limits the Aquasnap unit doesn't stop but it works in particular
conditions in order to preserve the compressor (frequency and for uptime limitation).
SM_30AW.indd 60
Tw
62 °C
61 ° C
L
60 ° C
[(EWT or LWT < (DELTA SP + 4°C))]
[(EWT or LWT < (DELTA SP + 3°C))]
[(EWT or LWT < (DELTA SP + 2°C )]
[(EWT and LWT > (DELTA SP + 5°C)]
Control management
Compressor OFF
M
N
TH WP
ON OFF
ON ON
OFF ON
OFF OFF
60
5
Tw:
Max(Actual
Water
Temperature
Entering,
Actual Water
Temperature
Exiting)
Tr: Actual
Refrigerant
Temperature
Fr(n):
real frequency
from the chiller
unit
Fhmin:
minimum
compressor
speed allowed
in heating
DELTA SP: NUI CODE
109
WP: Water Pump
TH: Trace heater
HP: Heat Pump
OAT: Outdoor Air
Temperature
EWT: Enter Water
Temperature
LWT: Leaving Water
Temperature
HP
OFF
OFF
ON
OFF
OAT: Outdoor Air
Temperature
LWT: Leaving Water
Temperature
30AW
14-03-2011 14:45:07