The Radiator Bleed That Warms Up Your Whole Room
The radiator in my office was hot at the bottom and cold at the top for an entire winter. I assumed it was just an old system being old. It was air, and it took about ten minutes to fix.
Why the Top Stays Cold
Air collects at the highest point of the radiator. Water cannot get up there, so that section never heats. The bottom stays warm because water is still sitting in it. If a radiator is cold at the top and warm at the bottom, that is almost always your answer.
What You Need
A radiator key, which costs a couple of dollars, plus a small cup or a towel. That is it.
Bleeding It
- Turn the heating off and let the system cool. Hot water under pressure is not something you want on your hand.
- Find the bleed valve at one end, usually the top corner.
- Hold the cup under it and turn the key counterclockwise a quarter turn.
- You will hear a hiss. That is the air leaving. Wait for it.
- When a steady stream of water appears with no spitting, close the valve.
If It Keeps Happening
Bleeding a radiator every month means air is getting into the system somewhere. That is a system issue, not a radiator issue. You may need a plumber to check the pressure and look for a leak or a bad seal. Once a year is normal. Weekly is not.
📋 Quick Summary: Cold at the top and warm at the bottom means trapped air. Cool the system down, then open the bleed valve until water runs steady.