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5712 717 v1.0
Vitotronic 100, KW10B Installation, Start-up and Service
Alternate Control Function
A1 Auxiliary input - heat demand
A1 Auxiliary input - 0-10VDC
This auxiliary input A1 can be used for one of two
functions based on the DIP switch setting (S6.7).
Refer to the altering settings on page 23 of this manual.
By default (with S6.7 in the OFF position), the control
comes set to allow a dry contact to provide a demand to
the control. A typical application for this kind of demand
may be a call from zone valve, snow melting demand,
external heat demand or any other kind of demand that
is required over and above the outdoor reset function.
When the control senses a closed contact, the internal
control set point is set to 176° F (80° C). The stages
will be fired to satisfy the new boiler set point.
Opening the contact will reset the boiler to the current set
point that is being calculated either from DHW or outdoor
reset.
WARNING
Ensure that only dry contacts are applied here as damage
to the PCB may occur otherwise.
The second function of the A1 auxiliary input (with S6.7
ON) is the ability to provide the control with a 0-10VDC
input signal to generate a boiler temperature set point.
Once the DIP switch is set correctly (see details on page
23), the signal can be applied to the control on the + and
- terminals. The signal is scaled from 2VDC to 10VDC to
equate to set point of 68° F (20° C) to 212° F (100° C)
respectively.
Signal below 1.9VDC will generate a 32° F (0° C) set
point.
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