Omnia Mechanical Group

571 Timpson Place Bronx, NY 10455

Phone: 212-534-2500

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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.

Our Privacy Policy

Omnia Mechanical Group(the “Company”) strives to ensure the highest standards for property listings and customer information privacy. Please review the following statement to learn about our company practices and policies. Please be aware that our Privacy Policy is subject to change at any time.

1. Purpose.

This Privacy Policy (“the Policy”) provides information on how the Company uses your personal information. By agreeing to the Policy, you agree to our collection and use of your personal information as described in the Policy. This Privacy Policy is effective for all new users of

2. Personal Information.

You can browse some areas of (“the Website”) without being a registered user. However, certain activities do require registration. (You consent to the transfer and storage of your information by registering with We may collect and store the following personal information:

  • Name, email, address, telephone number, and (depending on the service used), move-in dates;
  • Transactional information (such as lease terms, lease parties);
  • Computer sign-on data, statistics on page views, and traffic to and from the Website; and
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3. Use of Information.

Our primary purpose in collecting personal information is to provide you with a safe and user-friendly experience. For example, the Company may use your personal information to:

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  • As otherwise described to you at the time of collection.

We may occasionally ask you to complete optional surveys. These surveys are used to improve and customize your experience with

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The Company does not share any of your personal information with outside organizations, companies, individuals, etc. The only exception to this standard is if such a disclosure is reasonably necessary to respond to any and all legal processes.

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The Website may have links to other websites that may collect personally identifiable information about you. The Company is not responsible for the privacy practices of the content of those linked websites.

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The Website has strict security measures in place to protect you and your information from fraud. Once your information is provided to Antler Pump & Motor Corporation, we strive to ensure the confidentiality of your identity and information.

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The Company provides you with the opportunity to opt-out of receiving promotional and other non-essential, marketing-related communications from Antler Pump & Motor Corporation. If you would like to opt-out of these select communications, please see any of the Company’s email communications and follow the directions indicated.

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The Company does not guarantee the accuracy of information for any and all of its properties on the Website, and is not responsible for any errors or misrepresentations (made by Renters, the Client, or otherwise).

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Should your personal information change, please immediately update your information on the Website. This will ensure the accuracy of our records. The Company does retain personal information from closed accounts in order to comply with law and collect and disburse any fees owed.

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This Privacy Policy addresses only the use of information we collect from you. Since does not control the privacy policies of third parties, you are subject to the privacy policies of those third parties. It is advisable that you consult with the management of third parties before you disclose your personal information to others.

12. General

We may amend this Privacy Policy at any time by posting the amended terms on the Website. All amended terms are immediately effective after they are initially posted on the Website.

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