• "Holiday" activated in menu 6.
– Enter menu 6 and deactivate.
LOW ROOM TEMPERATURE
• Closed thermostats in several rooms.
– Set the thermostats to max in as many rooms as pos-
sible. Adjust the room temperature via the "Heating”
home screen, rather than turning down the thermostats.
• S1256 in incorrect operating mode.
– Enter menu 4.1 - "Operating mode". If "Auto" mode is
selected, select a higher value for "Stop heating" in
menu 7.1.10.2 - "Auto mode setting".
– If mode "Manual" is selected, select "Heating". If this is
not enough, also select "Additional heat".
• Too low set value on the automatic heating control.
– Adjust via the smart guide or home screen "Heating"
– If the room temperature is only low in cold weather, the
curve slope in menu 1.30.1 - "Curve, heating" may need
to be adjusted upwards.
• Too low or no operating prioritisation of heat.
– Enter menu 7.1.10.1 - "Operating prioritisation" and in-
crease the time for when heating is to be prioritised.
Note that if the time for heating is increased, the time
for hot water production is reduced, which can give a
smaller amount of hot water.
• "Holiday" activated in menu 6 - "Scheduling".
– Enter menu 6 and deactivate.
• External switch for changing room temperature activated.
– Check any external switches.
• Air in the climate system.
– Vent the climate system.
• Closed valves (QM31), (QM32) to the climate system.
– Open the valves.
HIGH ROOM TEMPERATURE
• Too high set value on the automatic heating control.
– Adjust via the smart guide or home screen "Heating"
– If the room temperature is only high in cold weather,
the curve slope in menu 1.30.1 - "Curve, heating" may
need to be adjusted downwards.
• External switch for changing room temperature activated.
– Check any external switches.
UNEVEN ROOM TEMPERATURE.
• Incorrectly set heating curve.
– Fine-tune the heating curve in menu 1.30.1.
• Too high set value on "dT at DOT"..
– Go to menu 7.1.6.2 (flow set. climate system) and reduce
the value of "DOT".
• Uneven flow over the radiators.
– Adjust the flow distribution between the radiators.
LOW SYSTEM PRESSURE
• Not enough water in the climate system.
– Fill the climate system with water and check for leaks
(see chapter "Filling and venting").
THE COMPRESSOR DOES NOT START
• There is no heating or hot water demand, nor cooling de-
mand (accessory is required for cooling).
– S1256 does not call on heating, hot water or cooling.
• Compressor blocked due to the temperature conditions.
– Wait until the temperature is within the product’s work-
ing range.
• Minimum time between compressor starts has not been
reached.
– Wait for at least 30 minutes and then check if the com-
pressor has started.
• Alarm tripped.
– Follow the display instructions.
WHINING NOISE IN THE RADIATORS
• Closed thermostats in the rooms and incorrectly set
heating curve.
– Set the thermostats to max in as many rooms as pos-
sible. Fine-tune the heating curve via home screen
heating, rather than choking the thermostats.
• Circulation pump speed set too high.
– Go to menu 7.1.2.2 (Pump speed heating medium GP1)
and reduce the speed of the circulation pump.
• Uneven flow over the radiators.
– Adjust the flow distribution between the radiators.
67Chapter 11 | Disturbances in comfortNIBE S1256
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