When chilly temperatures set in, having a properly working heating system is of the utmost importance. If you have a steam heating system, you’ll also need to know how to turn on a radiator. This guide outlines eight simple steps to turn up the heat, plus some troubleshooting tips.
How to Turn on a Radiator and Heat up a Room in 8 Steps
Too bad there isn’t an “on” button on the radiator
Photo: Cavan Images / Getty Images
Photo: Cavan Images / Getty Images
Written by Brionna Farney
Contributing Writer
Updated November 12, 2023
Difficulty
Easy
You've got this!
Time to complete
30 minutes
Extra troubleshooting will take more time.
Cost
Up to $25
You might need a thing or two.
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What you'll need:
TOOLS
- Radiator bleed key
- Towel
- Small bucket
- Small wire
- Needle-nose pliers (optional)
- Flathead screwdriver (optional)
Turn Off Your Heating System
Before turning on a radiator, ensure your heating system is off. You’ll turn your water-circulating or steam heat system on and off throughout this guide, so follow the steps carefully. When turning the system off, wait for the radiator to cool down completely before proceeding with the next step to avoid injury.
Find and Rotate the Control Valve
To turn on a radiator, start by rotating the control valve near the bottom of the radiator where the hot water pipes connect to it; you may also find a temperature dial (if it’s a thermostatic valve). Turn the control valve counterclockwise to open it, and make sure it’s open all of the way so the radiator can reach its maximum temperature.
Turn your heating system back on and determine if there is heat coming from the radiator. If the radiator is still cold after the system is up and running, proceed to the next step.
Locate the Bleed Valve
If a radiator is still not working after turning on the control valve, it may need bleeding. Bleeding a radiator means letting out any trapped air or clogged water. Find the radiator's bleed valve with your heating system turned back off and completely cooled down. This valve is usually at the top of the radiator on either the left or the right side.
Turn the Bleed Valve
Photo: Evgen_Prozhyrko / Getty ImagesYou will use a radiator key, sometimes called a bleed key, to turn the bleed valve. If you don’t have a radiator key, you can pick one up at a local hardware store or online. Sometimes, needle-nose pliers can turn the valve, or a flathead screwdriver might fit into a slot at the top of the valve.
Before turning the valve, hold a towel, small bucket, or cup beneath the valve to catch any drops of water. Using your radiator key (or pliers or screwdriver), slowly turn the valve counterclockwise about half a turn.
As you open the valve, you’ll hear a hissing noise as air escapes from the radiator and water fills the space within the system. Once the hissing stops and a steady stream of water starts coming out of the valve, it’s time to close it in the next step.
Close the Bleed Valve
Again, using your radiator key (or pliers or screwdriver), turn the bleed valve in the opposite direction (clockwise) to close it. Go slowly and be careful not to break the valve. You do not need to force the valve closed—stop turning once you feel a bit of resistance. Use your towel to wipe away any remaining water on the radiator.
Bleed the Remaining Radiators
Take the time to bleed the rest of the radiators within your system to ensure they aren’t causing any more common home radiator issues. Experts recommend bleeding all of your radiators twice a year to ensure they produce plenty of heat and to reduce the pressure in the heating system.
After bleeding all of the radiators, turn your heating system back on. Check your boiler pressure gauge—it should be between 1 and 2 bars. If the particular radiator you want to turn on is still not producing heat, turn your system back off and move on to the next step.
Unclog the Air Vent
About halfway down the side of a steam radiator, there will be a metal air vent. This vent is usually cone-shaped and has a small hole at the top. If the vent is clogged, the radiator won’t get hot. Use a small wire or sewing needle to puncture the hole at the top of the air vent. Also, ensure the vent is positioned vertically with the tip of the cone facing up.
With the air vent cleared and re-positioned, turn your heating system back on and determine if the radiator is heating up. If clearing the air vent did not fix the issue, you may have a larger issue that requires the assistance of an HVAC professional.
Repair or Replace the Radiator
Photo: enigma_images / Getty ImagesIf your radiator is still not heating up after trying all the methods in this guide, it’s time to call in the professionals. An HVAC contractor will inspect your steam heating system as a whole and can take apart the radiator to find any internal issues.
In a worst-case scenario, you may need to replace the entire system. Steam radiators can last decades, but there will come a time when you’ll need to swap out the system for a new one.
DIY vs. Hiring a Pro
Learning how to turn on a radiator is simple, as you can tell. Turning valves and unclogging vents is a DIY project that most people can tackle. You may need to purchase a radiator key, but this will cost less than $25. Hiring a local HVAC technician costs about $100 to $250 per hour if you're not feeling up to turning on and troubleshooting your radiator.
If your radiator still needs to be fixed by the end of this troubleshooting guide, you may need to pay between $100 and $500 for radiator repair prices. If it’s time for a whole new system, a radiator replacement costs $100 to $2,500 per unit, or $1,500 on average.
Frequently Asked Questions
It takes about five to 10 minutes for heat to reach a radiator, then about one hour until the radiator fully heats up a room. The exact duration depends on the size of the room and how far away the radiator is from the boiler heating system. Heating up an entire house could take up to two hours.
If you go to turn it counterclockwise and it won’t turn anymore, it’s open. Like most other valves, you should be able to turn a radiator valve counterclockwise (to the left) to open it and clockwise (right) to close it. To close a radiator valve, turn it clockwise until you meet some resistance and can’t turn anymore, but do so carefully to avoid breaking the valve.
The radiators closest in proximity to the boiler heating system will heat up first. Radiators in rooms farther away from the boiler will take longer to heat up and may be the coolest rooms in the house. The radiator unit itself should heat up evenly; otherwise, there may be trapped air inside it.
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