How to Bleed Your Radiators

Signs That It’s Time to Bleed Your Hot Water Radiators

Wondering if your radiators actually need bleeding? Here are some clear signs:

• Cold spots on the radiator: If your radiator feels warm at the bottom but cold at the top, it’s often a sign that air is trapped at the top, blocking the hot water and reducing the heating efficiency.
• Strange noises: Gurgling, bubbling noises, or banging sounds from your radiators can indicate that air pockets are caught within the system.
• Uneven heating: If some radiators in your home are slower to heat up or stay cooler than others, they may be holding trapped air bubbles.

If any of these issues sound familiar, then bleeding your radiators will likely help. Tackling these simple steps now, before the heating season fully sets in, can make an inefficient heating system more reliable when you need it most.

How to Bleed Your Radiators

The radiator bleeding process is a DIY-friendly task, even if you’ve never done it before.

1. Turn off the heat. Start by turning off the active heating system and letting the entire radiator cool down completely. This prevents any hot water from escaping and helps avoid burns.
2. Gather your tools. You’ll need a radiator key (a small tool available at most hardware stores) or a flathead screwdriver for some screw-type valves. Keep a towel or a small bowl nearby to catch any drips.
3. Locate the radiator bleed valve. At the top corner of each radiator, you’ll find a small valve called a bleed valve. When the bleed screw is opened, this is where the trapped air escapes.
4. Insert the radiator key or screwdriver. Place the radiator key or flat-head screwdriver into the radiator valve and slowly turn it counterclockwise. You should hear a hissing sound from the cold radiator, which is the air escaping. Hold the cloth or bowl below the valve to catch any water that may start to leak.
5. Wait until water trickles out. As soon as the hissing stops and a steady trickle of water begins to flow, the air has been fully released. Quickly turn the valve clockwise to close it again; you don't want it to become a steady stream water, so shut it down quickly once the flow begins to escalate. This is the most crucial step of the process.
6. Check each radiator in your home. Repeat this process with each radiator in your home, moving from the radiator closest to the boiler and working outwards. This order can help keep your system balanced.
7. Check the boiler for proper water pressure. Once you’re done, take a look at your boiler’s pressure gauge. Bleeding radiators can sometimes cause a slight drop in boiler pressure level, and you may need to top it up according to your boiler’s manual to avoid a pressure imbalance.
8. Turn the heat back on. As the system heats back up, check the distribution of heat, radiator to radiator.

Extra Tips for New Homeowners

If you’re new to home maintenance, here are a few additional tips to help you out:

• Get a radiator key: These are inexpensive and handy to have around the house. Radiator keys are widely available and usually come in a universal size that fits most radiator types.
• Watch for warning signs: During the colder months, keep an eye (and ear) out for signs that your heating system might need attention, especially after extended use.
• Bleeding annually: Most radiators benefit from being bled at least once a year, ideally in the fall. Regularly doing this small home improvement task keeps your system efficient, temperature consistent, and helps prevents complex issues down the line.

FAQ

How often should I bleed my radiators?

Most recommend bleeding your radiators once a year, ideally in the fall before heavy use. However, if you notice any signs of trapped air, such as cold spots or gurgling sounds, it’s worth bleeding them as needed rather than as a timed annual chore.

Can bleeding radiators lower my energy bills?

Yes, bleeding your radiators can result in energy savings because it helps hot water circulates properly. When radiators heat evenly and the thermostat in your home is steadily at the set temperature, your boiler doesn’t have to work as hard, which can reduce your heating bills over time, especially in winter.

What if my radiator is still cold after bleeding?

If your radiator remains cold even after bleeding, the issue might be due to a buildup of sludge rather than trapped air. In this case, it's worth it to get your system professionally flushed to remove any sediment buildup that blocks the hot water flow.