Construction
The new ALFA2 heater is about 1/3 smaller and lighter than its predecessor. Thanks to the enlarged heat exchange area of the exchanger and the use of stainless steel, we were able to reduce the size of the unit and use less but much higher quality material. Furthermore, thanks to the optimal design of the exchanger (air passes through it in laminar flow), it was possible to use smaller axial fans, which have 30-50% lower electricity consumption at the same air output. All external and internal components of the heat exchanger are made exclusively of stainless steel and the heater casing is made of painted galvanized sheet metal.
In order to comply with the strict Ekodesign 2021 (COMMISSION REGULATION (EU) 2016/2281) regulations and operate the equipment as non-condensing, it was necessary to design the device to modulate 100-55% as much as possible and most of the time operate at maximum efficiency, which is LCV efficiency (chimney loss) of 94.5% and GCV efficiency (efficiency based on combustion heat) of 84% at values NOx of only 54 mg / kWh. All these values were verified by an authorized testing laboratory in accordance with the new standard EN 17082/2020.
Exchanger
The exchanger for the new ALFA2 is welded from highly resistant EN 1.4541 stainless steel sheets, which can withstand temperatures up to 850 °C for a long time. It consists of individual half-lamellae, first formed by drawing the material and then cut by fiber laser into the desired shape. The half-lamellae are cut into three basic shapes. The exchanger contains the largest number of central half-lamellae, one is left to close the exchanger, and one is used as a flange, into which holes are cut for mounting the burner flange and flue. The half-lamellas prepared in this way are welded in a fully automatic robotic workplace. The result is an all-stainless steel exchanger, which is composed of individual fins, where the flue gasses flow inside and the air that is heated from the outside.
Eco mode
After the room thermostat issues a heating request, the device starts up and the premix burner is lit. Next, the ANTI-CONDENSATION mode starts and runs until the modulation temperature is reached. When the modulation temperature is reached, the device automatically switches to ECO mode, with a fixed modulation temperature of 140 °C. The device tries to maintain the EKO modulation temperature throughout the operation. As a result, the flue gas temperature oscillates between 130 – 150 °C, which guarantees maximum efficiency. Thanks to this mode, gas consumption is about 10% lower than the original units, which did not meet the E=kodesign regulations.
Anti-condensation mode
ALFA2 TOP can prevent the formation of condensate in the device with maximum certainty, because it doesn’t allow for the room thermostat to switch off until it reaches the modulation temperature. This helps to evaporate a small amount of condensate in the condensate tank, but it has little effect on the elimination of condensate in long uninsulated or coaxial fume extraction.
Design specifics
The ALFA2 device operates in the ECO mode throughout the entire modulation. When designing, it is necessary to take into account that even though the air heater starts to heat with “max” power, most of the time it will heat the hall with a power close to “min.” and the flue gas temperature will be around 140 °C. This means that in the case of long and non-insulated fume extraction systems, condensation will take place. Therefore, we recommend that you always include a condensate sump with condensate drain at the beginning of the flue, and insulate the entire length of the flue. For shorter fume extraction systems with a length of approx. 2 m, the risk of condensation in the flue is minimal, but it cannot be completely ruled out, especially if the hall is only tempered, e.g. to 10 °C. When using coaxial fume extraction, use only one that has the inner flue pipe insulated.
