Technical data

13
Outside Air Sensor
To be used with cascade controller,
the optional outside temperature
sensor must be wired directly to the
cascade controller to exploit the full
control functionality, including
weather compensation.
This sensor must be connected
to the control scheme and must
be positioned on an external wall
with northerly aspect.
Room Sensor Non Adjustable
For installations where controls
are not to be adjusted by the
building occupants, the QAA10 non
adjustable room sensor may be used.
This prevents tampering and
communicates room temperature
to RVA47 Cascade Controller.
No user adjustment is possible.
Room Sensor Offset Adjustable
For installations where limited control
is required by the building occupants,
the QAA50 offset adjustable room
sensor ay be used. This permits
adjustment +/- 3°C from the
programmed temperature set point
and communicates room temperature
to RVA47 Cascade Controller.
Zone Controller
Multiple heating zones may
be connected into the system
to provide a comprehensive
building control.
A zone controller and sensors
are required for each zone.
Control Features:
n 3 programmable periods per day
n Optimised start / stop
n Constant or variable temperature
n Pump output to control zone pump
via relay/contactor (not HHL supply)
n Mixing valve output
n Reduced temperature/night set back
for non occupancy hours
n Frost protection
n 7 day time clock with automatic
summer/winter clock adjustment
Zone Control
Additional to the cascade control,
multiple heating zones can be
connected into the system to provide
a comprehensive building control.
Each zone has an individual 3 program
timer, which together with outside
and inside air temperature sensors can
provide optimised start/stop for that
circuit.
Using the RVA46 controller, zones
can be configured for either constant
temperature or variable temperature.
Heat demand is calculated according
to zone air temperature and where
applicable outside air temperature.
Using the same compensation heat
curves and parallel displacement curves
as the cascade controller (shown on
page 15), each zone can be configured
to operate individually from any other
zone in the system. Individual night set
back and frost protection settings as
well as summer shut down settings can
also be programmed.
Demands for heat are communicated
to the cascade controller via the LPB
bus to initiate heat generation when
required. The cascade will set the
primary circuit operating temperature
according to the highest heat demand,
therefore where multiple heating zones
are used, these are best configured
as variable temperature circuits
making use of the zone controller
mixing valve outputs. This way, when
differing heat requirements exist across
multiple zones, the lower temperature
zones can modulate the mixing
valve to maintain water temperature
requirements.
Each zone control has a pump output
that can be used to control the zone
pump via a relay/contactor. When a
heat demand exists within the zone,
the pump will be started until the
demand for heat is satisfied.
An individual room air temperature
sensor is required in each zone. The
same selection of room temperature
sensors are used as for the cascade
controller. External air temperature
is communicated via the LPB from
the sensor connected to the cascade
controller.
Each zone controller also has a DHW
time program which can be used
to initiate the cascade controller for
hot water production. Using the
same cylinder as the cascade circuit,
the cascade will produce hot water
whenever there is a hot water demand
from one of the zones or from the
cascade controller integral hot water
time program providing a central hot
water facility.
Domestic Hot Water
A domestic hot water cylinder may be
connected to the cascade controller.
With the immersion temperature
sensor connected directly to the
cascade controller, hot water will be
produced whenever there is a demand
within the timer programmed periods.
The hot water circuit is provided with
its own three period time clock, and
also has a separate night set back
feature, frost protection and an anti
legionella function.
The primary circuit to the calorifier
is controlled using the domestic hot
water pump output which is energised
only when a hot water demand
is present. This pump should be
connected to the controller via
a relay contactor.