Viessmann VITOTRONIC 300 Installation And Service Instructions Manual page 61

Vitotronic 300, GW5B & MW1B Installation and Service
Boiler Temperature Control of the Vitotronic 300, GW5B
ON
OFF
set
low heat average heat
demand demand
ON
OFF
set
low heat average heat
demand demand
ON
OFF
set
low heat average heat
demand demand
Switching hysteresis, burner
Permanent switching hysteresis
Code "04:0"
Time
Heat demand-dependent switching hysteresis
The heat demand-dependent switching hysteresis takes
the boiler load into account.
The switching hysteresis, i.e the burner runtime varies
high heat
subject to actual heat demand.
demand
ERB50 function
Code "04:1"
Time
Subject to heat demand, values between 6 and 12 K
result.
high heat
demand
ERB80 function
Time
Code "04:2"
Subject to heat demand, values between 6 and 20 K
result.
Control sequence
Boiler goes cold
(set value −2 K)
The burner start signal is selected as the set boiler water
high heat
temperature minus 2 K, and the burner starts its own
demand
monitoring program.
Note: The burner start may be delayed by a few minutes
Boiler heats up
(Set value +2 K)
The burner shuts down.
Modulating burner:
The burner stop point is determined by the stop
differential (coding address "13" in the "Boiler" group).
(continued)
subject to the number of auxiliary circuits and the
combustion type.
Function Description
61