Solution to thermal failure of electric heating furnace

If the upper radiator is overheating, the lower radiator is too cold in a two-pipe, top-split heating system; or if the upper radiator is not warm in a multi-story building with a bottom-feed system, the lower radiator is overheating. This vertical thermal imbalance can occur for two reasons:

1. There is a significant difference in the heat transfer flow through the upper and lower radiators. To correct this problem, turn down the valve on the upper radiator branch pipe. First, reducing the heat transfer flow can cause the lower end of the branch pipe to become clogged with scale, iron oxide, and other debris. Second, this increases the resistance of the circulation system, disrupting the pressure balance between the system's various loops. In this case, promptly remove the debris from the pipe section or replace the branch pipe to reduce resistance and restore the pressure balance between the system's various loops.

2. If the upper radiator is not warm, it may be due to air trapped in the upper radiator. Check the radiator's bleed valve or the exhaust valve on the pipe to remove the air. Alternatively, the system may be depleted of water and should be refilled.

Sometimes, a loop may overheat. When there are multiple loops connected in parallel in a system, some loops may not heat up, a phenomenon known as horizontal imbalance. In this case, the master control valves on each loop should be adjusted to balance the pressure losses between the loops, thereby eliminating uneven heating and cooling.

Overheating of radiators near the heat inlet, while radiators at the end of a multi-pass system do not heat up, is also a case of horizontal thermal imbalance. This phenomenon occurs because the valves at the front are wide open, creating an imbalance between the pressure applied by each loop and the pressure consumed by that loop. As a result, the heat transfer in radiators near the main line inlet has a short path, resulting in minimal pressure loss and a high residual pressure. This results in an excessively high heat transfer flow rate within the loop, exceeding the actual required value. In radiators at the far end, the heat transfer has a long path, resulting in greater pressure loss, and a reduced heat transfer flow rate through the far end loop. In this case, the valve on the branch pipe at the system inlet should be closed, and the bleed valve on the terminal air tank should be opened or the automatic vent valve checked to remove any remaining air from the system.