Bleeding your radiators will keep your home warmer this winter.
If you have hot water radiators like many homes in the Twin Cities, you might need to bleed air from your radiators to keep your heat consistent throughout your home. If your system is running but one or more of your radiators feels colder than the rest, that’s a good sign that there is air trapped inside that prevents the hot water from flowing freely through all the fins.
When to complete: This is a task that you may need to repeat. Do it at the beginning of heating season, and again as needed. Check up on the system throughout the season by feeling the radiators for cold spots or checking the valve at the radiator furthest from the boiler to see if air is present.
What you need:
- Radiator key (or flat-head screwdriver for screw-type valves.)
- Small container or rag to catch water
Step 1: Check the pressure gauge on your boiler. It should be 1 pound of pressure for every 2 feet the water needs to rise. For most homes, this will be in the range of 12-15 lbs. or 20-25 feet. The gauge on your boiler is probably helpfully marked with the pressure your home needs.
Step 2: If the pressure is too low, add water to your system.* Open the valve that comes from your water supply – you will hear water flow into the system. Stop when the gauge reaches the target pressure level.
Step 3: Bleed the air from your radiators, starting on the top floor with the radiator that is furthest from the boiler. With a cup or rag held below the spout, use the radiator key to open the bleed valve. First, you’ll hear air rush out. When the air is removed, water will flow out. The air that is removed will often have an odor that’s similar to kerosene – this is normal.
Step 4: Repeat with other radiators. As you are releasing the air, the pressure on your system will drop as well. You may need to return to Step 2 once or twice before you finish the whole house.
Step 5: Add water to the system one more time to bring it to your target pressure.
*To be on the safe side, don’t add ice-cold water to an already hot system. Turn off your heat for an hour or so before beginning this task, especially later in winter when tap water is extremely cold.