If you have a hydronic, or water-based heating system, then you have radiators that run through your home. The radiators allow heated water to move through the metal pipes and heat the air as they pass. Sometimes water will no longer move through the pipes in one section of your house. Keep reading to find out why this might happen and also how you can fix the issue.
Why Does A Radiator Fill With Air?
In some cases, a radiator may have a small leak or there may be a pin-sized hole somewhere in your heating system. This allows small bits of water to escape and air enters the pipe to replace the missing water. This air forms pockets in the heating system and the air moves through the heating system with the water. Once air builds up and bubbles become larger, they become trapped in a radiator. This blocks the water from flowing through the pipes.
In other cases, you may not have a leak in the system at all. Air bubbles gather in the main water tank or heat exchanger unit of the system. This air then travels with the water as it is pumped to the radiators. Sometimes the bubbles get trapped, like in the scenario where a leak is present. The air will often remain in the system and build until it is released.
How Is The Air Removed?
If one zone of your house is no longer being heated, then it is wise to bleed the air from your radiators. You can do this in several ways. If your radiators have bleeder valves on them, then place a small bowl under the valve opening. Open the valve and let the water release. You will notice air coming out as well and you may hear a slight hissing sound. Once the hissing sound stops, close the valve.
If you do not see any bleeder valves on the radiators, then you may need to flush air out from the hydronic pipes themselves that sit in your basement. These pipes typically have a drain valve on each return pipe. Most returns are labeled so you can release water or air if there is a need. Place a bucket underneath the return and turn the knob on the appropriate pipe to release water and air. You will see a slow and inconsistent flow as air moves out of the pipe. When water flow is consistent, close the valve.
Keep in mind that you should only need to bleed your heating system about once every few months. If you find yourself completing the task much more often, contact an HVAC service professional so a leak can be detected.