Atag BC100124, Appliance Technical Manual

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Gradient speed CH
The gradient allows the boiler to increase the CH water temperature with a pre-set (parameter 5) number of degrees per
minute. The number of degrees can be set between 1 and 15 per minute (factory set to 5).
The Gradient control is a calculated increase of the T-Set value. When the flow temperature is 5 degrees higher than the
T-set temperature, the boiler will switch off. So if you set the max flow temperature to 80 the boiler will switch off at 85.
Scenario:
Boiler set with parameter 5 with a gradient speed CH of 5 = 5°C per minute increase.
CH T-max 80°C
If the boiler starts with 35°C flow temperature the boiler will calculate a T-set temperature using the gradient line.
This will look to raise the flow temperature to 40°C after 1 minute and look to raise it a further 5°C the minute after, as
an on ongoing gradient line, which is recalculated as the boiler is working. If the boiler goes past this gradient line T-set
temperature by more than 5°C the boiler will switch off. The boiler 5 minute anti-cycle feature will operate. When the
boiler comes back on again it will start the process off again with the new flow temperature.
A boiler / system that cannot get rid of this heat effectively will see a rapid increase in the flow temperature (more
than the 5°C per minute it has been set up to do). The flow temperature will quickly go over the calculated T-set
temperature (gradient) by the 5°C and would switch off.
The following gradient speed settings are recommended for each type of heating system:
1 – 2 underfloor heating
4 – 5 Radiator convectors
7 – 8 Indirect heated air heater
Setting the gradient parameter to P5 = 0
If you set this to 0, you switch off the gradient control and the T-set is the temperature set with the CH button (normally 80°C).
In this case there is no limit to the number of degrees temperature increase per minute and the boiler will try to reach its
set point as quickly as possible.
So the boiler will go to full load and try to reach the set water temperature set under the CH button.
There is no restriction to the number of degrees temperature increase per minute (The brake is off). The boiler will then
modulate, because the delta T is reached. The boiler will try and maintain the delta T across the heat exchanger around 20°C.
Heating line
The heating line is used when an outside sensor or ONE controller is used via a Wi-Fi connection to give an outside
temperature. The boiler takes into account the outside temperature to give a calculated flow temperature to the
heating system. The ONE is an OpenTherm thermostat and will overrule some settings in the boiler.
This is shown in the weather compensator section.
Summer-eco temperature
If an outside sensor is fitted, then the summer eco mode becomes active.
The summer-eco temperature is at what temperature the boiler stops operating for heating, because the temperature is
higher than the set summer-eco temperature. This is based on the average outside temperature, with the calculation of
the average outside temperature (Factory setting 25°C).
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