Frost Protection - Viessmann VITOTRONIC 200 Service Instructions Manual

Buffer cylinder
(cont.)
Operating status in time
program for buffer cylinder
"Top"
"Standard"
"Fixd value"
Operating status
"Vitotronic 200" operating instructions

Frost protection

If the buffer temperature falls below the frost protection
limit, the heat pump control unit immediately switches
on the heat pump and the instantaneous heating water
heater.
Any activated block of the instantaneous heating water
heater for the central heating becomes ineffective
("Enable instant. heating water heater for central
heating 7902" set to "0").
Temperature limit Central heating with heating water buf-
fer cylinder or heating water/coolant
buffer cylinder
Frost protection limit
Shutdown limit
Low loss header
For the hydraulic separation of the secondary circuits
and the heating circuits.
The heat pump control unit treats a low loss header in
the same way as a small heating water buffer cylinder.
In the heat pump control unit, the low loss header must
therefore be configured as a heating water buffer cylin-
der ("Enable buffer cylinder/low loss header
7200").
The buffer temperature sensor is installed either in the
low loss header or downstream of the low loss header
in the system flow.
Buffer cylinder cooling
ON
Set buffer temperature plus
"Start hysteresis coolant
buffer cylinder 722B" at
buffer temperature sensor is
exceeded.
OFF
Set buffer temperature minus "Stop hysteresis
coolant buffer cylinder 7223" at buffer tempera-
ture sensor is undershot.
Set buffer temperature at buffer temperature
■
sensor is undershot.
and
Set buffer temperature minus "Stop hysteresis
■
coolant buffer cylinder 7223" at secondary cir-
cuit return temperature sensor is undershot.
"Temp in op. status fixed value for coolant
■
buff cyl. 7220" at buffer temperature sensor is
undershot.
and
"Temp in op. status fixed value for coolant
■
buff cyl. 7220" minus "Stop hysteresis, buffer
cylinder 7209" at secondary circuit return tem-
perature sensor is undershot.
Frost protection heating ends when the buffer temper-
ature exceeds the stop limit.
Room cooling with heating water/coolant
buffer cylinder
3 °C
10 °C
Note
To ensure that as much of the return temperature of
the heating circuits as possible is transferred to the
return of the secondary circuit, the flow rate on the
heating circuit side must be higher than the heat pump
flow rate on the secondary side.
Function description
/
3 °C
6 °C
47