Bosch Heatronic 4000 Installation & Operating Instructions Manual page 27

Wiring a Boiler Inlet Sensor (7738003451)
A single boiler inlet sensor measures the water temperature entering the boilers.
• Connect one wire from the boiler inlet sensor to the Boil In terminal 24.
• Connect the second wire to the Com terminal 25.
Wiring a Primary Supply Sensor (7738003451)
A primary supply sensor measures the temperature of water coming from the boiler plant. This sensor should
be installed on the supply pipe ahead of the tees supplying any loads.
• Connect one wire from the primary supply sensor to the Prim Sup terminal 18.
• Connect the second wire to the Com terminal 19.
Wiring a Primary Return Sensor (7738003451)
A primary return sensor measures the temperature returning to the boiler plant. This sensor can be installed
on the return side of the primary loop, ahead of the boiler plant piping.
• Connect one wire from the boiler return sensor to the Prim Ret terminal 20.
• Connect the second wire to the Com terminal 22.
Wiring a DHW Sensor (7738003451)
A DHW sensor is used to measure the temperature of a DHW tank. For indirect DHW heating, the DHW sensor
can be used instead of a DHW aquastat. For direct DHW heating, only the DHW sensor can be used to control the
temperature of the DHW tank.
• Connect one wire from the DHW sensor to the DHW terminal 21.
• Connect the second wire to the Com terminal 22.
Wiring a Flow Sensor (provided by others)
An analog flow sensor can be connected to the Heatronic 4000 to provide flow monitoring. The control
supports an analog 4-20 mA type flow sensor. Using the primary supply sensor & the primary return sensor,
energy output can be calculated & displayed from the flow measurement. The flow sensor can also be used
to prove primary pump flow.
• Connect one wire from the flow sensor to the 20 V dc Out terminal 11.
• Connect the second wire to mA (+) In terminal 12.
BTC461503101C | 6720810369 (2018/03) 27 of 60
Terminals 24, 25
Com Boil Com
Flue In
23 24 25
No Pow er
Terminals 18, 19
Out Prim Com
doo r Sup
(-)
17 18 19
No Pow er
Terminals 20, 22
Prim DHW Com
Ret
20 21 22
No Pow er
Terminals 21 to 22
Prim DHW Com
Ret
20 21 22
No Pow er
Terminals 11, 12
20V mA
dc (+)
Out In
11 12
Flow
Sen sor
Heatronic 4000