Air duct heaters are widely used in industrial air supply, drying rooms, and air conditioning auxiliary heating systems. However, prolonged continuous operation often leads to several typical issues, most of which are related to duct design, scaling, fan matching, and control protection.
I. Most common: uneven heating, local overheating
1.The airflow velocity is uneven in the duct, with some areas having strong winds and others weak, leading to localized dry burning of the electric heating tube.
2. There are vortices and dead zones in the air duct, preventing heat dissipation, which leads to excessively high surface temperatures on the heating tube, accelerating aging and even causing it to burn out.
3. Significant fluctuations in the inlet air temperature, along with intermittent high and low loads on the heater, can also exacerbate localized overheating.
II. Damaged, burned-out, or leaking electric heating tubes
1. Prolonged high temperatures combined with dust and oil stains adhering to the pipe walls reduce heat dissipation, leading to overheating and melting of the pipe body.
2. Moist air ducts with corrosive gases cause magnesium oxide powder to absorb moisture, leading to insulation degradation, leakage, and tripping.
3. The flange seal is not tight, allowing water vapor to enter the junction box and causing a short circuit.
4. Incorrect material selection (e.g., using ordinary stainless steel in environments with acids, alkalis, or sulfur-containing flue gases) leads to corrosion perforation.
III. Issues caused by the mismatch between the fan and the heater
1. The fan must stop before the heater, or the heater must be turned off when there is no wind or only a breeze. Otherwise, direct dry burning will cause damage.
2. Insufficient air volume, excessive heater power, frequent overtemperature protection activation, and even direct burnout.
3. Excessive duct resistance results in insufficient actual airflow, manifested as inability to raise the outlet air temperature despite the equipment being very hot.
Ⅳ. Condensation, Freezing, and Moisture Issues
During cold starts, condensation in the air duct adheres to the heating tube, causing a significant impact when power is applied.
2. In winter, heating outdoor fresh air can easily lead to fin icing, duct blockage, and a sharp decline in heating efficiency.
3. Without moisture-proof treatment after shutdown, the insulation fails to meet standards upon restart, rendering power transmission impossible.
V. Control and Safety Protection Issues
1. Overtemperature protector, dry burn temperature control failure, poses fire hazards.
2. Contactors exhibit contact erosion and frequent tripping, resulting in intermittent heating.
3. No fan interlock, manual misoperation leads to windless dry burning.
Ⅵ. Decreased efficiency and increased energy consumption
1. Accumulation of dust, fluff, and grease in the fin gaps leads to significant reduction in heat transfer efficiency.
2. Scaling and oxidation on the heating tube surface reduce thermal conductivity, resulting in higher power consumption at the same temperature.
3. Severe air leakage in the air duct results in significant heat loss.
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Post time: Apr-08-2026
