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Blauberg ENH 125-1.2-1 S21 V.2

Duct heater for supply air reheating.
  • Description
  • Characteristics
  • Capacity diagram
  • Downloads
  • Designation key
  • Compatibility chart
  • Dimensions

The heater is designed for integration into a ventilation system and joint operation with an air handling unit equipped with a control system used to switch on the heater and control its operation. The heater maintains the supply duct air temperature at a point set by the unit controller.Compatible with Ø 125 up to 315 mm air ducts.


The heater design ensures its mounting on the round ducts in any position by means of clamps (included in delivery). The air flow direction shall match the direction of the arrow on the heater casing.In case of horizontal mounting the control box must be installed with the cover upwards. Swivel range from the normal position up to max. 90°. Do not install the control box with the cover downwards.


The casing, the junction box and the heater cover are made of galvanized steel with the heating elements in stainless steel. The heater casing is additionally heat-insulated with 20 mm non-flammable mineral wool layer. The heaters are equipped with rubber seals for airtight connection to the air ducts. ENH S21 V.2 duct heaters are equipped with a factory-wired power supply cable and control cable, as well as a duct temperature sensor which is connected to the air handling unit. The temperature is controlled smoothly by the air handling unit controller using a PWM signal in cycles of 10 seconds. Load commutation is carried out by a semiconductor device (triac). The heaters are equipped with overheat thermostats:

  • main overheat protection with automatic reset at +60 °С;
  • emergency overheat protection with manual reset at +90 °С.
Parameter ENH 125-1.2-1 S21 V.2 Measurement unit
Current 5.2 A
Power 1200 W
Min. air flow 90 m³/h
Min. air flow 25 l/s
Insulation incombustible mineral wool, 20 mm mm
Casing material galvanized steel -
Air duct for round air ducts -
Connection diameter 125 mm
Capacity diagram
Capacity diagram
  • Selection method:
  • Air capacity:
  • Pressure:
Operating point
  • Air capacity: --
  • Pressure: ---
Documents archieve
Documents archieve
Select a document type
  • Catalogues
  • Technical documentation
  • Certificates
S21 - user's manual (pdf 611.32Kb)
EVH S21 V.2 / ENH S21 V.2 - user's manual (pdf 1.5Mb)
ENH S21 V.2 - data sheet (pdf 432.69Kb)
ENH S21 V.2 - image (png 504.76Kb)
Designation key
Designation key
Series Connected air duct diameter [mm]   Heater power [kW]   Number of phases Compatibility with automation
ENH 125; 150; 160; 200; 250; 315 0.6; 0.8; 1.2; 1.7; 2.0; 3.0 1: single-phase S21 V.2: compatible with an S21 automation without a DB-9M connector
Compatibility chart
Compatibility chart
Heater model Unit model
ENH 125 S21 V.2 KOMFORT EC SB unit with a ∅ 125 pipe and an S21 automation without a DB-9M connector

Model Overall dimensions [mm]
Ø D B H L L1
ENH 125-1.2-1 S21 V.2 125 164 249 306 192
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