How to adjust radiator heat

Updated February 21, 2017

Radiators provide comfortable heat without the annoying drafts or noise created by forced-air blower fans. Hot water or steam radiators in a home feature manually operated, adjustable valves to regulate the flow of water or steam from a boiler to the radiators. Newer valves are equipped with incremental settings that help to eliminate the trial and error adjustment methods of older valves. Either way, you can adjust the heat produced by a radiator with no tools or previous radiator experience.

Turn the boiler on and allow it to warm up completely. This will take from 15 minutes to one hour, depending on the size of your boiler.

Locate the radiator water-supply valve. The valve will have a distinctive handle used for opening and closing and may be located on either side of the radiator.

Turn the handle of the valve clockwise until it is fully closed.

Open the valve counterclockwise one-half turn. As the radiator produces heat, add or reduce the flow of the hot water or steam by turning the handle in increments according to comfort. It is better to start off cooler than warmer because hot radiators take more time to cool.

Follow Steps 1 and 2 for older adjustment valves.

Rotate the dial indicator on the radiator control to the desired temperature level number. The "0" mark indicates the off position and "28" represents a temperature of near 29.4 degrees Celsius. Marked increments in between make temperature changes more accurate.

Turn the dial indicator to "8" for frost protection when you are away for extended periods. This setting will maintain a temperature of approximately 7.22 degrees Celsius, well above the frost level.


Hot-water system radiator valves can be installed at the upper or lower areas of radiators. Steam-system valves, however, are always located at the lower area. Thermostatically controlled valves on your radiators also enable you to adjust the heat in each room or area of your home individually. Newer control valves vary according to the manufacturer. Follow all recommendations and instructions available for your particular unit.

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About the Author

Max Stout began writing in 2000 and started focusing primarily on non-fiction articles in 2008. Now retired, Stout writes technical articles with a focus on home improvement and maintenance. Previously, he has worked in the vocational trades such as automotive, home construction, residential plumbing and electric, and industrial wire and cable. Max also earned a degree of biblical metaphysician from Trinity Seminars Ministry Academy.