Air heaters

Air heaters type NPA

NPA air heaters are designed to produce hot process air and are mainly used in grain or herb dryers. They are also used to heat large storage facilities, plastic tunnels, greenhouses, etc.

The machines are adapted to work with grain dryers, like, for example, Araj, Riela, Drzewicz, etc. They may be used wherever it is possible to use renewable fuels, often inutilely lost.


NPA air heaters use a counter current biomass combustion system with adjustable and properly arranged air blow enabling the achievement of better performance of the combustion process. This process is as follows: the air blowing fan to the combustion chamber, controlled by a microprocessor controller, sucks in air and feeds it to the combustion chamber to the places of the combustion of the charge. The heat produced as a result of the combustion is released into the air supplied by the air blowing fan. Then, the hot air can pass to the receiver through the duct system. The air is heated in exchangers directly from the heat generated during the combustion of straw (without a medium, like, for example, oil or water). This design enables the achievement of the increased efficiency of the machines and higher air temperatures.

In order to obtain an optimum exhaust composition it is advisable to use seasoned straw with a moisture content of up to 15%. NPA air heaters are not subject to Technical Inspection and registration at the Inspectorate of Technical Inspection.


The basic fuel for firing NPA air heaters is pressed straw of four types of grain and rape with a moisture content of up to 15% in the form of bales with dimensions of fi1500x1200 mm. The combustion of straw with a higher moisture content will reduce thermal efficiency and accelerate the wear of the heater and the chimney installation. The combustion of straw seasoned less than a year may accelerate the corrosive wear of the heater. Moreover, the combustion of straw with a moisture content of above 30% is energetically unacceptable and economically unjustified. Where necessary, an alternative fuel may be wood waste and branches.


  • -efficiency of about 75%
  • cheap fuel (straw, hay, etc.) 4 kg straw= 1 litre of heating oil
  • easy operation
  • compact design
  • environmentally-friendly combustion of straw

Each heater has CE marking, the construction meets the requirements of European Union Directives.

It is possible to produce heaters with parameters other than those listed above.

DetailsUnitNPA 250NPA 350NPA 600NPA 850NPA 1100NPA 1300NPA 1600NPA 2400
Boiler power rating*kW2503506008501100130016002400
Heated air temperatureC110105
Heated air flow ratem3/h~7000~10000~18000~22000~36000~40000~54000~72000
1 bale fi1 bale fi2 bales fi2 bales fi3 bales fi3 bales fi3 bales fi4 bales fi
Fuel load120x120150x120150x120150x120150x120150x120180x120180x120
Straw moisture%15
Weight of one chargekg~140-170~240-250~480-500~480-500~720-750~720-750~960-1000~1200-1400
Weight of unit with ceramics (gross)kg~7000~9000~11000~13000~19000~21000~25000~30000
Required exhaust draftPa~55~65~75~85~95
Chimney heightm12151620222424
Chimney sectionfi300350450500600600800900
Thermal efficiency%~75
Installed capacitykW~9~9~14~18~29~29~44~49
Heater length **mm A31003550474052606250625062508200
with fan **450047007000780088008800920011200
Heater width **mm B17002100210021002100210024002400
with control box **23502450245024502450245027502750
Heater height **mm H21802575259027002700280032003300