Carrier Aqua SNAP PLUS 30AWH004H Manuel D'installation page 18

Additional Water pump (ADD WP )
It is possible to connect an additional water pump through the
pins 12 and N. It is managed in the following way:
The additional water pump activation depending by the NUI
code 156.
1. ON/ OFF depending on the outdoor unit water pump logic,
there is an output (1ph ~ 230V, 2A max) that can be
programmed using the remote User Comfort Interface (see
the control manual, Installation Menu code 106).
Two different strategies are possible based on Outdoor Air
Temperature:
1) Turn off heat pump and activate backup heat source. This
function is activated when OAT < Temperature set in NUI
code 148 (default value -20°C). In this region heat pump
turns off and external backup is activated following one of
below logic (NUI CODE 154):
its own regulation.
(NUI CODE 154=1)
(CODE 154=2) in case NUI is not installed/available.
2) Both heat pump and backup heat source activated in case
Units without an integrated pump allow driving an external
one.
contact) is available to force off the unit.
dry contact open the system turns ON and works in the last
10 30AWH
NUI code 148.
2. ON/ OFF depending on the outdoor unit water pump logic,
If OAT < temperature set in NUI code 148.
The additional water pump activation depending by the
NUI code 157 (0. always ON, 1. always OFF or 2. ON/OFF
depending by EHS).
activated when OAT < Temperature set in NUI code 150 (but
NUI
keeps working and backup heater turns on if set point on
water is not reached by 5°C (value can be set with NUI CODE
152) for 10 minutes (value can be set with NUI CODE 151).
Backup heater turns off when set point on water is reached
again.
IMPORTANT NOTICE :
In case of SHW activation (pins 13-15 closed) heat pump will
turn on and backup heater will turn off. This will happen in
both the above strategies.
WARNING :
In case of EHS installation, it is mandatory to install a
thermal switch on the water circuit to protect the system
from too high water temperatures. This protection item has
to be located immediately downstream the EHS.
It is possible to use this feature connected with different
external control systems and/or safety devices. For example
in case of danger an external safety device could send an
output alarm signal to close the contact. So the outdoor unit
turns off and remains in that condition until the dry contact
is reopened.
(Fig. 17)