A construction heater equipped with a highly energy-efficient fan and heated by a burner free of emissions. Exhaust gases from the burning contributes to room warming so that the efficiency approaches 100%. The fan is of radial type and is free from noise and reaches almost 95% efficiency. The heater has a design that allows the heated air to be distributed equally in all directions and by using the Coanda effect reaches the hot air all over the floor surface. This provides uniform drying of the concrete or which are intended to be dried. The heater is equipped with a supermarket trolley wheels. With a motor of 50 W is obtained 500 cbm/h air flow and a warming of the air by 14 degrees Celsius. By the heated air is heated again to get a highly efficient energy cycle. Construction heaters are used with different effects on the recorder due to the outdoor climate. Production involves the spinning of the body are continuously welded to a frame that holds together the structure. The fan is attached to a base plate with the brackets on the motor. The plate is attached to the body with welded attachments.