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How Does a Radiator Steam Vent Work? New Technology Makes Steam Venting More Precise

With heat season upon us in New York City, many property owners and managers are challenged when it comes to creating the ideal indoor temperature. If you’re struggling with rooms that are too hot or too cold, it could be that your radiator steam vents need attention. In this post, Calray Boilers answers the common question, “How does a radiator steam vent work?” and offers expert advice for improving radiator performance with new technology and simple maintenance tips.

How Does a Radiator Steam Vent Work?

Steam venting basics

Steam vents on radiator systems are actually very elemental and yet elegant controls that, at their most essential, haven’t changed in over 100 years of use in New York City homes. The vent allows air to fill the radiator. Eventually, this air is replaced by steam sent from the commercial boiler when the heat is turned on.

As the steam fills the radiator, it pushes air out of the vent, also known as the air valve or steam valve. The steam vent is heat-sensitive. When it warms up enough, it closes and stops letting air out. This then traps steam in the radiator in order to provide warmth for the room where it’s located.

Different types of traditional steam vents

As you might have guessed, a one-size-fits-all approach to steam vents doesn’t work well because of different heat needs and various building configurations. Therefore, there are different sizes of air valves based on the need for more airflow (more heat) or less airflow (less heat):

• #4 – used on radiators with thermostats and those that affect thermostats
• #5 – used in warm rooms and on radiators close to the boiler
• #6 – used in cold rooms and on radiators located farther from the boiler
• C – used on radiators located farthest from the boiler
• D – used where a large volume of venting is needed, such as on very large radiators or on long branches
• #1 – used at the terminal end of steam piping mains

One-pipe vs. two-pipe steam radiators

All steam radiators use steam vents. Your condo or co-op building may have one-pipe or two-pipe radiators. In the case of the former, one pipe provides steam to the radiator, and the same pipe carries condensate back to the boiler when the steam has cooled. With two-pipe radiators, a separate pipe transports the condensate to the return system. Depending on which type of radiators are present, you may hear more or less air escaping from the steam vent in the form of that well-known “hiss.”

Thermostatic Radiator Valves for More Precise Temperature Control

New steam vent technology

Even with all the different air valve sizes available, it was tough to get that Goldilocks “just right” temperature in certain units for some folks. And traditionally, the heat was either on or off; there was no adjustment to lower the heat slightly, such as when you went to work or to bed at night. All that changed with the invention of the thermostatic radiator valve.

Thermostatic radiator valves (TRVs) allow anyone to get more exact control of their radiator temperature. These valves replace conventional steam vents and have more precise settings inside. They “converse” with a thermostat to raise or lower the temperature slightly by adjusting the flow of air through the valve. A dial on the valve lets users set a baseline temperature from which increases or decreases in heat are created.

Tips for the Best Radiator Steam Vent Performance

Expert advice from Calray Boilers

Whether your building uses conventional radiator steam valves or newer thermostatic valves, you can improve their performance by following these tips:

1. Remember to use the right size conventional valve for the size of the radiator and location in question.
2. Steam valves can break or clog over time. During the off-season, when you bleed your radiators, give them a good once-over for cleaning or replacement. Usually, soaking a clogged valve in vinegar or lemon juice will remove mineral scale and sediment built up inside.
3. A leaking steam valve may not be broken or clogged. Some valves need to be in the upright position to work correctly, so make sure a leaky valve isn’t one of these that has been inadvertently tipped sideways.
4. Don’t confuse the steam valve with the control valve at the base of the radiator. The control valve should always remain fully open during heat season. If it’s off, the heat is off. Period. There are only two settings to the control valve: on or off.
5. Never under any circumstances remove the steam vent while the radiator is on and receiving steam. Scalding deaths have resulted from this. Occupants with young children should take care that their children never touch the radiator steam valve.
6. Thermostatic valves are best paired with programmable smart thermostats for the most precise temperature control. Smart thermostats can be controlled remotely via a personal electronic device. The programmable element means they can be preset for automatic temperature fluctuations at desired times.
7. It can sometimes take a day or two of experimenting to get the right interior temperature with a TRV. Be sure to give it time at different settings to find the right one for the unit occupant. Just like different size conventional steam valves are necessary for various locations around the building, different TRV settings may be required for upper vs. lower floors or small vs. large rooms.

Of course, making your radiator steam vents work properly all depends on having a boiler that’s in tip-top condition. If you’re overdue for a professional maintenance check before winter starts in earnest, it’s time to schedule an appointment ASAP. Call Calray Boilers today at 212-722-5506 to set up your expert consultation.