
General
This function enables an external additional heater, e.g.
an electric boiler, wood boiler, pellet boiler, oil boiler,
gas boiler or district heating, to assist with the heating.
The heat pump/indoor module controls a shunt valve
(QN11) and a circulation pump (GP10) via AXC 40. If the
heat pump/indoor module cannot manage to maintain
the correct supply temperature (BT25), the additional
heat starts. When the temperature on the boiler sensor
(BT52) exceeds the set value, the heat pump transmits
a signal to the shunt (QN11) to open from the additional
heat. The shunt (QN11) is regulated so that the true
supply temperature agrees with the heat pump’s theor-
etically calculated set point value. When the heating
demand drops sufficiently, so additional heat is no longer
required, the shunt (QN11) closes completely.
Factory-set minimum operating time for the boiler is 12
hours.
The function smart energy source can be selected if you
want to prioritise automatically between heat pump
operation and additional heat versus the best price or
environmental impact.
COMPATIBLE PRODUCTS
• S1155
• S1255
• VVM S320
• VVM S325
Pipe connections
The external circulation pump (GP10) is located on the
supply line to the climate system after the temperature
sensor (BT25).
SHUNT VALVE
The shunt valve (QN11) must be placed on the supply
line to the climate system after the heat pump according
to the outline diagram.
• Connect the supply line from the
heat pump to the external heat
source via the T-pipe to port B on
the shunt valve (closes on reduce
signal).
• Connect the supply line to the climate system from
the shunt valve to the common port AB (always open)
• Connect the supply line from the external additional
heat to the shunt valve to port A (opens on increase
signal).
9Chapter 4 | Shunt controlled additional heatAXC 40
Shunt controlled additional heat