Viessmann 301.BS090, Installation And Service Instructions For Contractors

Page: 35 / 100

35
Terminals Function Explanation
21X5 Groundwater/cold water flow switch Requires floating contact:
■
Closed:
Heat pump in operation
■
Open:
Heat pump shut down
No jumper should be installed if a flow switch is con-
nected.
38X4 External fault message, dry cooler Requires floating contact:
■
Closed:
Dry cooler fault
■
Open:
Dry cooler OK
19X0 Optional heat pump emergency stop
switch Requires floating contact:
■
Closed:
Heat pump in operation
■
Open:
Heat pump shut down
No jumper should be installed if a flow switch is con-
nected.
19X2 Power supply utility control Economy tariff peak block
19X4 External demand 1 Requires floating contact:
■
Closed:
Demand 1 active
No jumper should be installed if a start command is
connected.
19X6 External demand 2 Requires floating contact:
■
Closed:
Demand 2 active
No jumper should be installed if a start command is
connected.
19x8 External changeover command
Heating/cooling Requires floating contact:
■
Closed: Cooling
■
Open: Heating
External demand 1+2
Terminal 19x4,
1+2
Terminal 19x6,
1+2 Description
Open Open Not enabled
Closed Open Enable 1 stage
Open Closed Enable 2 stages
Closed Closed Enable 3 stages
Note
With the contact closed, 24 VDC must be available
at terminal number 2. Note
The terminal strip for internal heat pump components
is position
6 in the graphic on page 30.
Installation sequence
Overview of electrical connections
(cont.)
5549 991 GB
Installation