If your home’s radiators aren’t heating up properly, air trapped in the system could be the culprit. Bleeding your radiators is a simple yet effective solution to this common problem.
This guide will walk you through the process of bleeding a radiator, helping you restore efficient heating to your home.
What Is Radiator Bleeding?
Radiator bleeding is the process of releasing trapped air from your heating system. This air can accumulate over time, preventing hot water from circulating effectively through your radiators.
By bleeding your radiators, you allow this air to escape, ensuring optimal heat distribution throughout your home.
Why Do Radiators Need Bleeding?
Radiators need bleeding because air can enter the system in various ways. As water heats and cools, it can release dissolved gases. In older systems, air might be drawn in through small leaks or during maintenance.
This air, being lighter than water, rises to the top of radiators, creating cold spots and reducing heating efficiency.
Signs Your Radiator Needs Bleeding
Several indicators suggest your radiator might need bleeding, such as:
- Cold spots at the top of the radiator while the bottom is warm
- Radiators that take longer than usual to heat up
- Gurgling or bubbling noises coming from the radiators
- Increased energy bills due to inefficient heating
How to Bleed a Radiator in 7 Simple Steps
Follow this simple step-by-step guide to check and bleed your radiators:
#1. Turn Off the Heat.
The first and most crucial step of how to bleed a radiator is to turn off the heat. Not only can an active heating system introduce more air into the line, but you also need time for the heat to dissipate so that you don’t burn your face or hands when you remove the bleed valve.
If the radiator is still hot, removing the bleed valve will result in steam and near-boiling water spraying out of the valve in your direction. Turn off the heating system and wait for the heat to dissipate. Check to ensure the radiator is cool before proceeding.
#2. Prepare the Are.
While you’re waiting for the radiators to cool down, you can prepare the area by placing a bucket at the base of the radiator to catch any water that exits through the bleed valve.
Now is also a good time to grab an old rag or cloth to help contain the spray of water droplets and to clean up any water that spills on the floor.
#3. Open the Radiator Valves.
Check to make sure that both the intake and exit valves of the radiator are open before inserting the radiator key into the bleed screw. If you don’t have a radiator key, you can usually find one at the local home improvement store.
Alternatively, you might be able to use a screwdriver or wrench to operate the bleed valve. With your tool of choice inserted into the bleed screw, turn the screw counterclockwise to open the valve.
As you open the valve, you should begin to hear a hissing sound as the air escapes the radiator. Make sure your clothes and bucket are ready, and don’t be surprised when a little bit of water starts to drip out of the valve. Use the cloth to catch the drops, and keep your eye on the valve.
#4. Close the Bleed Valve.
When all the air has been released from the radiator, you will see a steady stream of water begin to pour out of the bleed valve. If the bucket is in the right position, you should be able to catch any water before it can soak the floor.
Tighten the bleed valve to stop the flow of water by turning the bleed screw clockwise. Check to make sure that there aren’t any leaks, then use your rag to wipe up any water that missed the bucket.
#5. Repeat for Each Radiator.
Empty the bucket and wring out the cloth or rag, then proceed to the next radiator in the home. Repeat this process with every radiator.
Work from the radiator that is further away from the boiler to the closest. Start on the lowest floor of the home and move up one floor at a time.
#6. Check the Pressure Level of Boiler.
After bleeding every radiator in the home, check the pressure level of the boiler system. It should have a pressure level of around 12 to 15 psi to function properly.
If the pressure level is too low, top off the boiler by opening the water feed valve until the pressure gauge reaches 12 to 15 psi. If your boiler has an automatic fill system, this shouldn’t be a problem.
#7. Turn on Heat and Test the System.
Turn on the heating system and wait for the water to begin circulating through the radiators. After about 20 minutes, check each radiator to ensure that they are producing heat and that the heat is being evenly dispersed from the bottom to the top of the radiator.
How Does Air Get into a Hot Water System?
How does air get into a closed plumbing system? In some cases, it’s not air at all. If your pipes are a mix of iron and copper or brass, galvanic corrosion may be releasing hydrogen gas.
Or, you might have an older pressure relief tank, which relies on a pillow of air to prevent dangerous pressure from building up in the heating system. Cooler water dissolves some of the air, and when the system kicks on, the heat drives the gas out of solution.
Modern pressure tanks separate the water from the air with a rubber bladder. Old steam systems can actually suck air in. As the steam cools, it shrinks dramatically, causing a partial vacuum.
You can eliminate or reduce the buildup of air and other gasses in your system by being sure there’s an air eliminator installed just after the boiler. This is a job for a plumber.
FAQs.
Do you bleed a radiator when the heat is on or off?
You should always check to see that your central heating system or boiler is turned off and your radiator has completely cooled before attempting to bleed it. If left on, the radiator contains hot water, and you risk scalding yourself in the process.
How often do I need to bleed my radiators?
It’s recommended to bleed your radiators at least once a year, or maybe twice if you live in an area with an unusually long winter season. It’s best to do it at the beginning of the heating season. This is an easy process that doesn’t take much time, but it can significantly contribute to the efficiency of your heating system. By taking this step you ensure that they continue to operate optimally.
How do you know when the radiator is fully bled?
Towards the end of the process, you will hear a hissing sound as trapped air escapes. This sound is followed by the trickle of water out of the bleed valve. This should turn into a steady stream of water and you can now close the bleed valve by turning the key clockwise.
Do I need a radiator key?
If you don’t have a radiator key, you can use a flathead screwdriver instead. It will fit into the notches of the bleed valve in the same fashion as a key. Turn counterclockwise to open the valve and clockwise to close it.
How do I know if I have a water or steam radiator?
To determine what type of heating system you have in your home, check the number of pipes connected to your radiator. One pipe indicates it is a steam system. Two pipes may indicate either a steam or hot water system. In a hot water system, there will be a second pipe used to return the condensed or cooled water back to the broiler.