The Content Of The Article:

A radiator is a device that emits heat for the purpose of heating a room. For this, two main technologies are used: convection or radiation. Sometimes, various malfunctions may occur and it may happen that the radiator is hot up and cold down. What are the possible causes of this phenomenon? What steps to take?

Hot radiator at the top and cold at the bottom

Hot radiator at the top and cold at the bottom

Thermostatic valve not sufficiently open

A radiator hot up and cold at the bottom can be caused by incorrect handling of the thermostatic valve: it is possible that it is not sufficiently open and in this case it automatically clamps the hot water supply. This is one of the simplest causes to solve. The thermostatic valve must then be fully opened to obtain a uniform heating of the radiator. If the situation does not change, this is another potentially more serious problem.

Note that beyond the thermostatic valve too little open, the poor hot water circulation may cause an imbalance in the operation of the radiator. In particular, it is necessary to check the elbow side, but also the adjustment tee (at the return to the boiler), which must not be closed.

System tamping

A hot radiator at the top and cold at the bottom may also be due to partial or total slugging of the heating circuit. In general, the mud accumulates in the lower part of the radiator. This situation prevents the water from circulating normally. If this is the case, it is necessary to proceed with a a rinse part or all of the circuit. Depending on the problem, parts may need to be changed. Given the complexity of the situation, it is preferable to entrust this type of intervention to a professional heating engineer in this area.

Other possible causes

In addition to the thermostatic faucet and a possible sludge, other factors can be at the origin of a hot radiator up and cold down. In this case, check:

  • the radiator trap. In the event of a malfunction, an air bubble can be created and alter the flow of water
  • insufficient flow at the circulator
  • insufficient pressure in the heating circuit

When there is the slightest doubt as to the origin of a radiator heater malfunction, it is always preferable (and highly recommended) to seek the advice of a specialist. This heating expert will be able to establish an accurate diagnosis and make the necessary repairs respecting all the safety standards in force.


Video Instruction: How to fix a radiator that won't get hot - By Trade Radiators