Knowledge in the heating tube of the oven

What is the difference between the number of 4 and 6 heating tubes in the oven? The more electric heating tubes are not the better, because the power of the oven is generally fixed. The more electric heating tubes, the smaller the power allocated to each tube. Slower heating, increased preheating time, and lower thermal efficiency will occur. Baked food is very unfavorable. Therefore, the design of the oven heating tube should consider the baking effect. Generally, ovens above 50L use 6 tubes, and 15-50L use 4 tubes.