TM_i-BX(-N)_NC05_00_06_20_EN
MEHITS S.p.A.
●
TECHNICAL MANUAL
Version NC05 - Translation of the Original Instructions
44
4.11
ELECTRIC HEATER AT THE DELIVERY
The purpose of the delivery electric heater is to assist in the production of hot water produced using the heat pump (compressor), when this is not
able to meet the heat demand as a result of an inhibition (operation in replacement mode; in this case it will come on instead of the compressor), or
when the heat load exceeds the power that can be produced by the machine (operation in integration mode; in this case it will come on at the same
time as the compressor).
Using the parameter, activation will be p
ossible for antifreeze purposes and during the defrost cycle: see paragraphs “6.11.3
” “6.11.4
4.11.1
REPLACEMENT HEATER
OBLIGATION:
For the function to be performed correctly, probe BT9 must be connected. For the correct positioning refer to the use /
installation manual
By setting the parameter
010G
= REPLACE HP, the heater is activated in system heating or DHW (the latter only if there is no configured DHW
storage tank dedicated heater), replacing the compressor if this unable to meet a setpoint due to inhibition for the following reasons:
•
transducer or pressure switch high pressure intervention
•
transducer or pressure switch low pressure intervention
•
operation outside envelope
•
external air temperature higher or lower than the operating limits set by parameters
0311
(set by the installer) or
133Z
(machine operation
absolute lower limit) and
0515
•
maximum water temperature based on the external air temperature, as defined by parameters
133E
,
133F
,
133G
,
133H
•
LOP, MOP and EEV low overheating alarms
•
probe fault (with the exception of regulation probes).
The regulation of the heater for the production of system water will follow the same regulation algorithm of the compressor in heating operation. The
heater will be activated immediately, ignoring any delay set in parameter
0616
.
For DHW production see paragraph “7.2.3
The previously described replacement is automatic. However, manual replacement is also possible by setting parameter
0620
= MANUAL; in this
case, the water will only be heated using the heater, inhibiting compressor operation. This mode is normally used in case of compressor fault.
The switching on of the heater will be as follows:
ON
Delivery heater
(step 1 and 2)
OFF
Water T BT9 [°C]
Water temperature
setpoint
Regulation hysteresis
When configured as replacement, the heater switches on based on the water temperature, irrespective of the external air temperature: Therefore,
parameter
0303
, switching on based on the external air temperature, will be ignored.
In case of intervention of
the primary system flow switch (DI2) after the “flow switch alarm” delay,
1403
, the heater is disabled.
The heater operation is inhibited if the “Demand limit” (DI8) contact is active (see the “
” paragraph).
4.11.2
INTEGRATION HEATER
By setting parameter
010G
= INTEGRATE HP, the heater is activated in system heating or DHW (the latter only if there is no dedicated DHW storage
tank heater configured), to assist the operation of the compressor.
If the enable based on the external air temperature is set to
0303
= NO, the heaters will always be activated in case of insufficient heat, irrespective
of the external air temperature.
If the enable based on the external air temperature is set to
0303
= YES, the heater will be enabled based on the following criteria:
