Heating Basics How to Bleed the System

Dear heating customers, the heating system is currently being gradually filled with water, and the heating season is fast approaching. However, air trapped in the heating system has become one of the key factors hindering circulation and affecting temperature. We would therefore like to provide you with instructions on how to bleed air from radiators and underfloor heating systems.

For systems using radiators, top-floor residents in traditional, non-individualized systems with a single supply and return line must bleed their radiators; otherwise, residents on lower floors may not receive adequate heat.

For individualized systems, first ensure that all valves are open. Residents with radiator heating can use a screwdriver or similar tool to open the bleed valve at the top of their radiator (located on the left or right side) to release air. Once a steady stream of water flows out, the bleeding process is complete. Be sure to bleed all radiators in each group completely; if even one group remains unbleeded, it will affect the temperature. It is especially important not to fully open the bleed valves, as this could cause them to come loose and result in a water leak.

For users with underfloor heating, follow these steps to bleed the system:

1. Close the main supply and return valves for the heating system (the manifold is typically located inside a kitchen cabinet);

2. Close the small regulating valves for each loop on the underfloor heating manifold;

3. Open the main return valve;

4. First, open the upper and lower regulating valves for the same loop on the manifold, then open the supply bleed valve to release air. Once all air has been purged, close this valve and open the regulating valve for the next loop. Continue in this manner until air has been completely purged from each loop and a steady flow of water emerges. It is recommended to place a towel near the bleed valve to prevent water from splashing;

5. Similarly, close the main return valve, open the main supply valve, and open the return air vent valve for each loop one by one to complete the bleeding process;

6. Open the supply and return regulating valves for each loop on the manifold, as well as the main radiator return valve, to resume normal heating.

Note: If you do not wish to bleed each loop individually, you can leave the branch valves open, close the return valve, open the supply valve, and then open the air vent valve to bleed the system.

Air accumulation is common during the initial stages of filling the system and starting the heating season. As the water temperature rises, trapped air will be released, and new gas may form. Additionally, if the heating supply is temporarily interrupted due to power outages, water outages, maintenance, or other reasons, air may accumulate in the heating system, requiring re-bleeding to ensure unobstructed hot water circulation.