Riello NXHM - Page 51

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ENGLISH
Symptom 7: Heat mode can’t change to DHW mode immediately
POSSIBLE CAUSES CORRECTIVE ACTION
Volume of tank is too small and the location of water temperatu-
re probe not high enough
• Set "dT1S5" to maximum value, and set "t_DHWHP_RESTRICT" to
minimum valve.
• Set "dT1SH" to 2°C.
• Enable TBH, and TBH should be controlled by the outdoor unit.
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fulllled, the heat pump will turn on.
• If both TBH and AHS are not available, try to change the postion of T5
probe (refer to 2 "General introduction").
Symptom 6: Space heating capacity shortage at low outdoor temperatures
Symptom 8: DHW mode can’t change to Heat mode immediately
POSSIBLE CAUSES CORRECTIVE ACTION
Heat exchanger for space heating not big enough
• Set "t_DHWHP_MAX" to minimum valve, the suggested valve is 60min.
• If circulating pump out of unit is not controlled by unit, try to connect it
to the unit.
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Space heating load is small Normal, no need for heating
Disinfect function is enabled but without TBH
• Disable disinfect function
• add TBH or AHS for DHW mode
Manual turn on the FAST WATER function, after the hot water
meets the requirements, the heat pump fails to switch to the
air-conditioning mode in time when the air conditioner is in de-
mand
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When the ambient temperature is low, the hot water is not
enough and the AHS is not operated or operated late
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DHW mode priority
If there is AHS or IBH connect to the unit, when the outdoor unit failed, the
hydraulic module board must run DHW mode till the water temperature
reach the setting temperature before change to heating mode.
Symptom 6: Space heating capacity shortage at low outdoor temperatures
Sy mptom 9: DHW mode heat pump stop work but setpoint not reached, space heating require heat but unit stay in DHW mode
POSSIBLE CAUSES CORRECTIVE ACTION
Surface of coil in the tank not large enough
The same solution for Symptom 7
TBH or AHS not available
Heat pump will stay in DHW mode untill "t_DHWHP_MAX" reached or
setpoint is reached. Add TBH or AHS for DHW mode,TBH and AHS should
be controlled by the unit.
Symptom 6: Space heating capacity shortage at low outdoor temperatures