If you have recently turned on your hydronic heating system and have noticed that water is not flowing freely through all of the radiators, then this may be frustrating to you. When this happens, you may experience some fairly severe cold spots in your home. The problem typically occurs when air gets stuck in a portion of the heating system. If you want to resolve this issue, then keep reading.
Open the Bleeder Valves
One of the easiest ways to remove air from your radiators is to open the bleeder valves attached to them. You specifically want to open the valves on the radiators that are not heating properly. Start by using your hands to feel all of the radiators in your home. Test for the ones that are cool to the touch. Once you find the radiators, look for a small protrusion on the right or left side of the radiator. This is the air bleeder valve. The valve will have either a slot in the middle or a square opening. A flathead screwdriver will fit into the slot and a valve key will fit into the square opening.
Place a small bowl or container underneath the valve and turn the valve counter-clockwise. You should hear a hissing sound as air releases from the system. Once water starts to release from the valve, close it.
If you cannot find any bleeder valves, then the heating system may have an automatic air release system. This type of system has an automatic air release valve located on one of the main hot water pipes. The valve is often installed on a high point of the system and looks like a circular brass or cast iron attachment. The part is a float valve that allows air to move a float up to the top of the canister. As the ball reaches the top of the device, air is released out of an opening on the side of the device. Unfortunately, the float can stick and air can become trapped in the hydronic hot water lines.
Most float valves will have manual bleeder valves on the side of them to release air if they stop working correctly. Look for this type of valve and try to release air. If air does release, then contact an HVAC professional or a plumber to have the automatic bleeder valve replaced.
Check the Flow Control Valve
Almost all hydronic heating systems will have valves that control the flow of water through the system. The valve opens when the system loses water through condensation, leaks, or the creation of steam. This helps to keep the volume of air down in the system and keeps water flowing freely. However, the valve can sometimes stick in the closed position. When this happens over a long period of time, air will build in the water pipes and the heating zones in your home will stop supplying your house with heat.
In most cases, you will notice heat reducing slowly inside your home. This happens as air builds in the pipes over time and radiators start to malfunction. If several radiators have stopped working suddenly, then a low volume of water may be the issue.
If you suspect a low flow of water, then you can check your flow control valve. To find the valve, inspect your heating system and identify the pipe that allows water to flow into the heater. Follow this pipe back from the heater until you see an inverted bell shaped device or a square protrusion. This will be the water flow control valve. Look for a lever or a button on the valve. When you activate the lever or the button, you should hear a rush of water running into the heater. If you do not hear this, then the valve is likely broken. Speak with your HVAC specialist so a replacement can be installed.