27
8.1
EXTERNAL WIRING
The appliance comes with a factory fitted (TA)
link to allow basic operation of the boiler via the
mode selector switch. If external controls are to
be added to the system, they must be connected
to the appliance as shown in the following
diagrams. For advice on controls that are not
featured in this book, please contact Vokera
technical on 0870 333 0520.
8.1.1
EXTERNAL WIRING LIMITATIONS
Any external wiring must remain within the limits
as detailed in the table below
CONNECTION
MAX. LENGTH
External sensor
30-metres
Room thermostat
30-metres
OT+ connection
30-metres
8.2
TYPICAL CONTROL APPLICATIONS
The appliance can be used with the following
controls:
•
Single-channel, voltage-free time clocks (fig.
39).
•
Programmable room thermostats (fig. 40).
•
OT+ control, please contact Vokera technical
for detailed instruction on specific OT+ controls.
•
Vokera external sensor.
8.3
OTHER DEVICES
Contact the controls manufacturer and/or Vokera
technical department should you require more
specific information on the suitability of a particular
control. Further guidance on the recommended
practice for the installation of external controls,
can be found in CHeSS – HC5/HC6
(www.energyefficiency.gov.uk).
SECTION 8
WIRING DIAGRAMS
8.4
VOKERA MECHANICAL CLOCK (code )
The Vokera mechanical clock (product code) is
entirely suitable for the Unica HE range and
eliminates the need for an external time control.
The kit is comprised of the following:
•
Mechanical clock
•
Wiring harness
•
instructions
Fig. 39
Fig. 41
U.H.T.
= underfloor heating thermostat
C.P.A.
= condensate pump alarm
E.S.
=
external sensor
OT+
=
ope connection
OPTIONAL DEVICE (24V) TERMINAL BLOCK
Fig. 40
Isolate the appliance from the electrical supply
and remove the clock blanking disc from the clock
aperture on the boiler. Keep the screws safe, as
they will be required to secure the programmer to
the aperture.
Connect the spade connections of the wiring
harness to the clock as shown in figure 39.
Connect the other end of the wiring harness as
detailed in figure 41.
Secure the clock to the clock aperture using the
screws previously removed from the blanking disc.
IMPORTANT
•
The boiler must always be supplied with a
permanent 230V electrical supply.
•
Always remove the link between TA & TA on the
appliance high-voltage terminal strip whenever
additional controls are connected to the
appliance.
•
Do not connect any controls or auxiliary
equipment to the low-voltage terminal strip, other
than that approved/supplied by Vokera Ltd.
