WLE and WLE-K Air Heaters

Simply more than hot air!

Directly fired, stationary air heaters are being used wherever direct, fast and cost-effective heating of large room volumes is required and no hot water is available as a carrier medium.


For efficient heating and temperature maintenance with high injection temperatures

Directly fired, stationary air heater for outside, mixed and recirculating air operation.

The room air is heated directly via the heat exchanger.
Oil or gas can be used as the heating medium.

  • With standard heat exchanger
  • Can be used standing or lying
  • Flue gas pipe connection behind - lateral connection possible
  • 2 suction grids right and left
  • Highly efficient fans with energetically optimized AC/EC drives


  • fan and drive on site


  • Condensate-free
  • regulation of room air temperature
    burner control „ON - OFF“
  • Capacity - full load 100% burner control „ON - OFF“
  • Capacity - partial load burner and fan 2-stage, coupling of burner stage with fan stage
  • Exhaust gas temperature even in partial load range > 170 ºC
  • Outside air operation in full and partial load burner control „ON - OFF“


  • High plant and heating efficiency
  • No transfer loss
  • Fast and low-cost assembly
  • Short heating-up periods

Long-lived and safe

  • Triple safety thermostat
  • Regulation
  • No freezing - no water-bearing parts
  • Long service life of heat exchanger due to highly heat-resistant steel


  • Many accessories (filters, regulation)
  • Variable exhaust gas pipe (3 sides)
  • Compact size


For heating and ventilation with controlled injection temperature and / or stepless capacity control

Directly fired, stationary air heater as standard WLE, however equipped for condensing operation.

  • With stainless heat exchanger
  • With condensate discharge pipe
  • Can be used standing or lying
  • Flue gas pipe connection behind - lateral connection possible
  • 2 suction grids right and left
  • Highly efficient fans with energetically optimized AC/EC drives


  • fan and drive on site


  • Use of modulating burners in a range of 30 - 100%
  • High efficiency up to 96%
  • Condensing operation by corrosion- and condensate-proof high-grade steel
  • Cost saving, since no regulating flaps
  • triple safety thermostat

Heat Exchanger

The centerpiece of air heater WLE-K is the heat exchanger with flue gas box made of corrosion-proof high-grade steel.


  • Flame reversal - thus large combustion chamber with favourable flow characteristics
  • Heating cavities with turbulators
  • Easy to clean
  • Long service life of combustion chamber due to high-grade materials

Please note

Condensate disposal acc. to ATV Information Sheet M 251. Observe local waste water guidelines resp. obtain authorization for granule neutralisation. Such plants are available for each capacity.


  • Condensing operation possible
  • Constant air inlet temperature regulation
    - modulating 30 - 100%
    - 2,3-step sliding
    - continuously variable
  • Outside air operation
    - modulating 30 - 100%
    - 2,3-step sliding
    - continuously variable


As a highly efficient system supplement for all ventilation areas

Weatherproof T1 / TB1
Direct-fired air conditioner in weatherproof design

Direcly fired air conditioning unit for locations where no hot water is available as heating medium and / or rapid heating with high efficiency and economy is required.

  • Power range 28 - 1317 kW
  • Air output range 1500 - 150 000 m³/h
  • Heating media oil and gas
  • Outside, mixed and recirculating air operation
  • All versions, also available in weatherproof construction
  • Can be used in all ventilation and air-conditioning units in combination with a heat recovery system


  • Guaranteed long service life of the heat exchanger due to the use of high-heat and corrosion-resistant stainless steel
  • immediate heating effect
  • high efficiency of up to 96 %
  • modern control for automatic, trouble-free and cost-optimized operation
  • plug-and-play delivery

Quality Guarantee

Garantie für Qualität Logo A plus
Garantie für Qualität Logo QZV
Garantie für Qualität Logo RLT
Garantie für Qualität Logo DVGW
Garantie für Qualität Logo TÜV
Garantie für Qualität Logo IP
Garantie für Qualität Logo ErP
Garantie für Qualität Logo CE

Operating modes and control

Outside, mixed and recirculating air operation

For effective and substance-sparing warmth

Outside air operation

WLE / WLE-K vertical with fresh air connection, duct air filter, butterfly valves. (Supply air via on-site duct and outlet grille)

The air to be heated is taken directly from outside.

On appropriate conditions, this procedure guarantees cleean, fresh air. In summer, outside air is brought directly into the room (pure ventilating operation).

Mixed air operation

WLE / WLE-K lying on wall bracket with air outlet hood (grille horizontal or vertical)

Outside air (mixing ratio variably adjustable) is sucked together with room air.

This procedure reduces heating costs, because partially already warmed air out of the heated room is used, covering also outside air demand.

Recirculating air operation

WLE / WLE-K vertical, free inlet, with air outlet hood (1-4-sided air outlet)

The air is taken from the room to be heated and blown back into the room after being heated.

This procedure causes lowest operating costs.


  • The heat requirement of churches is calculated according to DIN EN 1283-1.
  • The basic temperature must be maintained at 8 °C during the set-back phase.
  • The temperature must be maintained from approx. 12 °C to approx. 15 °C during periods of use.
  • The air outlet temperature at the air outlet grille must not exceed 45 °C.
  • The change in temperature during the heating-up and the cooling process may not exceed 1.5 K/h in churches with valuable equipment.

Control WOLF-Tronic

  • Supply air control via duct sensor and room sensor for averaging
  • room temperature sensor
  • Switch cabinet with remote control panel

Protection of historical monuments

Through the use of modern control technology, the hot-air heating also meets the high requirements of listed buildings. Coordinated control protects inventory and substance.