Determining The Boiler Set-Point - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Correction

Determining the boiler set-point

ºF ºC
194 90
176 80
158 70
140 60
122 50
104 40
86 30
68 20
50 10
0
20 15 10
68 60 50
Outside temperature
Legend
A Selector dial "tr
r " setting: 1 r r
B Selector dial "tr
r " setting: 2 r r
C Selector dial "tr
r " setting: 3 r r
D Selector dial "tr
r " setting: 4
r r
E Factory default
F Selector dial "tr
r r " setting: 6 r
G Selector dial "tr
r " setting: 7 r r
tr
Fig. 70
G
F
E
D
C
B
5 0 -5 -10 -15
41 32 23 14 5
Factory default
A
-20 ºC
-4 ºF
Troubleshooting
Room dependent control:
Outdoor temperature sensor not
connected
With no outdoor sensor installed, the
"tr r " dial will provide a constant r r
temperature set-point for the boiler
based on the dial position selected.
Setting the dial between 1 and 6 will
provide a set-point value of 81ºF to
178ºF / 27ºC to 81ºC respectively. The
dot between 4 and 5 represents the
factory default set-point value of
140ºF / 60ºC.
Weather dependent control:
Outdoor temperature sensor connected
With the outdoor sensor connected,
the boiler will automatically recognize
the sensor and switch the set-point dial
operation from constant temperature
calculated to outdoor reset calculated.
Adjusting the "tr r r r " dial will select the
heating curve corresponding with the
heating curve chart. The set-point will
be calculated from the design boiler
water temperature associated with the
heating curve selected, and reset from
the actual outdoor air temperature.
Setting the dial between 1 and 6 will
select the corresponding curve from
the chart. The dot between 4 and 5 is
the factory default curve.
Note:
Both the room dependent control and
the outdoor reset control strategies
require a closed contact at terminals
RT to generate a call for heat to the
boiler.
Setting the dial to "0" places the boiler
in freeze protection mode regardless of
the control option selected or the
contact position at RT.
69