Using a one-pipe thermostatic steam radiator valve, you can regulate the temperature and make every single radiator it’s own zone. For safety reasons, before you follow the steps below and in the video, make sure your thermostat is turned off.
Pro Tip: On a one-pipe steam system, the thermostatic valve controls the air vent to regulate how much steam enters the radiator. As Richard Trethewey demonstrated on a This Old House project, when the room reaches the set temperature, the valve stops venting air, which prevents steam from entering—essentially making every single radiator its own zone.
How Does a Steam Thermostatic Radiator Valve Work?
The head of the thermostatic radiator valve senses the temperature that it is in the room. The radiator pushes the steam through the supply pipe into the valve. When the temperature of the room and the air is the same, it doesn’t vent to prevent the room from over heating. Plumbing and heating expert Richard Trethewey demonstrates how this works in the video above.
In a reader Q&A for This Old House Magazine, Richard Trethewey explained the energy-saving benefits: “With a thermostatic valve on the incoming pipe of each upstairs radiator, the valve senses when the room has reached its temperature setting and automatically restricts the flow of hot water. The radiator doesn’t overheat; it just silently emits a steady, comfortable warmth.”
Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, explains that the thermostatic valve “makes every single radiator its own zone.” He adds that you only need to install them in “the rooms you want to be comfortable in.”
How to Install a Steam Radiator Valve in 9 Steps
- Close the valve at base of radiator.
- Turn off the room’s thermostat.
- Carefully unscrew the existing air vent from side of radiator.
- Put Teflon tape on threads of new thermostatic steam valve.
- Thread new steam valve into radiator; tighten with adjustable wrench.
- Apply Teflon tape to threads of old air vent.
- Thread old air vent into top of new steam valve.
- Open valve at base of radiator.
- Turn on the room’s thermostat.
Pro Tip: When removing the existing air vent, Richard Trethewey recommends hand-tightening carefully: “I wanna get this air vent out, and I don’t wanna break it, and I’m gonna use it’s hand-tight so I don’t overdo it.” Turn counterclockwise and go slowly—a broken air vent can be a costly setback.
Learn More: How to Install Thermostatic Radiator Valves
Tools You’ll Need
Adjustable wrench
