Viessmann VITOTRONIC 100 GC1B Service Manual download pdf (Page 105)

Functional description

105

Boiler Temperature Control

Brief description

The boiler water temperature is

controlled by switching the burner on

and off.

The set-point boiler water temperature

value is determined by the set-point

supply temperature values of the boiler

circuit (A1), the heating circuits with

mixing valve (from Vitotronic 050) and

the set-point supply temperature value

preset via coding address ”9b” as well

as the set-point domestic hot water

temperature, and is dependent on the

boiler and the heating and control

facilities installed.

In conjunction with Therm-Control:

The set-point boiler water temperature

is increased when the temperature falls

below the set-point value on the sensor

of the Therm-Control.

Coding addresses which influence

the boiler temperature control

02 to 06, 08 to 0b, 13 to 1C.

Functions

The boiler water temperature is

measured via a multiple sensor well by

three sensors separately:





Fixed high limit FHL

(liquid expansion)





Adjustable high limit AHL

(liquid expansion)





Boiler temperature sensor BTS

(change in resistance PT 500)

Upper limits of control range





Fixed high limit FHL

110°C / 230°F, can be adjusted to

100°C / 212 or 230°F





Adjustable high limit AHL

95°C/ 203°F, can be adjusted to

100°C / 212°F





Electronic maximum limit

Setting range: 20 to 127°C /

68 to 261°F

The maximum limit for the boiler

water temperature is defined in

coding address ”06”.

Lower limit of control range





The control unit regulates the boiler

water temperature in normal

operation and in the frost protection

mode according to the boiler

concerned (boiler coding card).

Control sequence

Boiler temperature falls

The burner override signal is set for a

boiler water temperature setpoint value

of –2°C / -4°F, and the burner starts

its own monitoring program. Depending

on the range of additional control

facilities and the method of firing,

burner override can be delayed by a

few minutes.

Boiler temperature rises

The switch-off point of the burner is

defined by the switch-off differential

(coding address ”13”).

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