The Whalen Company Fan Coil Airlock Symptoms & Resolutions

If a Whalen fan coil unit stops heating and cooling like it should, the problem is often a quick fix. An airlock, or air trapped in the system, is a common culprit that can halt all heat transfer in the HVAC system. Here are some symptoms and the resolutions you need to repair it.

Recognizing Airlock Symptoms in Fan Coil Units

One of the most obvious signs of an airlock issue is the complete loss of heating or cooling output from the fan coil unit. These issues tend to present with a specific pattern.

Primary airlock indicators:

• No heating or cooling despite the unit running
• Unit located on the top floor of a riser stack
• System appears operational but produces no temperature change

Understanding Why Airlocks Occur

Airlocks can develop when air becomes trapped in the water lines of the fan coil system. This air prevents proper water circulation through the coil, eliminating the unit’s ability to transfer cold or heat to the air passing through. Even a small amount of trapped air can block water flow completely.

The Simple Resolution Process

Luckily, resolving an airlock is pretty straightforward and doesn’t require any specialized tools. Each Whalen fan coil unit comes with a bleeder valve designed for this issue.

Step-by-Step Airlock Removal

• Step 1. Locate the bleeder valve. The air bleed valve is positioned in the discharge opening at the top of the unit.
• Step 2. Open the valve slowly. Turn the bleeder valve very gradually. Rushing this step can cause water spillage and won't improve the bleeding process.
• Step 3. Listen for escaping air. You should hear a hissing sound as trapped air exits the system through the valve.
• Step 4. Watch for the transition. Continue bleeding until the air stops and water begins to flow from the valve.
• Step 5. Close the valve. Once you see water coming out, shut the bleeder valve completely.
• Step 6. Verify operation. The unit should return to normal heating or cooling function immediately.

When to Perform This Maintenance

Though airlocks typically occur after initial installation or a system startup, they can also develop at other times such as:

• After system maintenance or repairs
• Following seasonal shutdowns and restarts
• When new water is added to the system
• After any work on the building's hydronic piping