Automatic steam radiator vents:

This article describes the use, adjustment, diagnosis & repair of automatic, thermostatically controlled steam heating radiator air vents or steam vents to control or balance steam heat in buildings. This article focuses on automatic vents for one pipe steam heating systems.

This article series answers most questions about all types of steam heating systems and gives important inspection, safety, and repair advice.

FAQs on Automatic or Thermostatically Controlled Steam Vents

These questions & answers about automatic steam vents on steam radiators or on steam piping were posted originally at STEAM VENTS, 1-PIPE SYSTEMS - be sure to review that article too.

Our photo (left) shows what looks like a Hoffman 1A float-type radiator steam vent. This is a residential low-pressure (1.5 psig) steam vent. Similar models include the Hoffman Model 40 (6 psig) and model 70A (11 psig).

[Click to enlarge any image]

On 2018-10-14 by (mod) - I want quiet steam vents on my radiators

William

A properly-set-up steam heating system is rather quiet.

If you are hearing loud whistles, shrieks, or hissing at your steam vents it's possible that the system pressure is set higher than needed or than proper.

In the ARTICLE INDEX ARTICLE INDEX to HEATING RADIATORS live link above you'll find articles on proper steam system pressure and pressure control settings.

If you also hear gurgling or bubbling in the steam heat piping system that may be a diagnostic clue. Blocked condensate return to the boiler can cause steam boiler operating trouble. Sometimes a junior service tech will try to "fix" a condensate return blockage by "pushing" condensate by raising steam system pressure above its usual (less than 1) psi pressure (for residential systems).

Before considering going to a forced hot water system take a look at your radiators: are they connected to two pipes or one? A one pipe steam system is even more costly to change to forced hot water, as you'd need to modify every radiator AND to run additional heating piping throughout the building.

Also take a look at TRVs - thermostatic radiator valves - to control your heat at each radiator. Because the TRV will close when the room is warm enough (as set on the valve itself), the steam movement will stop and the radiator will be totally silent.

Also

Ask the service tech to check the mainline vents in the steam piping. If such vents are needed and are not working, all of the air to be vented out of the system at the start of a heat-on cycle has to be pushed out of the radiator vents, increasing the length of time they have to remain open.

Also try some different vent models. The Maid-O-Mist # 40M 1/8 in. IPS Angled Steam Radiator Vent Valve is a rather quiet vent.

On 2018-10-14 by William

@William, Also I don't care what it costs. a $100 valve is nothing compared to getting sleep.

Hello - I am very sensitive to noise and I just replaced all 4 of my single pipe steam radiators to hoffmans 40's, model number 401440.

These are still way to noisy for me, it woke me up twice and I can't sleep. Is there anything better that is virtually silent? Or do I need to ditch the steam for hot water?

On 2017-02-23 by Anonymous

The heat-timer chart does not tell you varivalve CFM in closed position. Gorton 4 has 0.025 according to https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf . I was wondering if closed varivalve would be lower. I am looking for the slowest vent in one particular room.

On 2017-02-23 by (mod) -

Steam radiator vent rates

Gorton 4 - 0 to about 0.04 cubic feet per minute (CFM)

Flair 101 - 0 to about 0.20 CFM

Hoffman 1A - 0 to about 0.20 CFM

Varivalve - 0 to about 0.8 CFM

-- source http://www.heat-timer.com/varivalve/

But why do you want a slowest steam vent? If you're interested in reducing the radiator heat output there are probably better ways to do so using a thermostatic radiator valve.

On 2017-02-22 y Lazar

Hi,
In Closed position, how Verivalve compares to Gorton 4 or Hoffman 1? I am looking for the slowest possible air vent.

On 2017-02-22 by (mod) -

Anon:

Given the low cost and ease of replacement, if I have a steam vent that won't close I replace it.

On 2017-02-22 by Anonymous

Did you figure out why this vent wasn't turning off? I have the same problem, leaking water as well.

On 2016-11-03 by Shelly

riser pipe steam vent clicks and nothing happens.

On 2015-12-31 by (mod) -

I would open the radiator inlet valve fully. If the rad is not getting hot your steam vent is probably not working.

On 2015-12-31 by Dexter

I have a one pipe system with adjustable valves from one quarter to full open to close where should I set it to so I can get the radiotor hot

On 2015-12-01 by (mod) -

George

If the new vent also does not shut off perhaps

It is the wrong vent model and is not reaching the temperature necessary for it to close

or debris is clogging it

or it's not properly located or mounted

Are you seeing water coming out of the vent. Some Model 4 steam vents close only against air temperature and not against rising water in the vent body.

Is the line where the vent is mounted hot or cool?

What is the pressure of your steam system; the steam vent may not be matched tot he pressure range.

Finally, can you send me (page bottom CONTACT link) a link to any information about your valve and some sharp photos of it? There are many steam vents but I've not found literature for the model you cite.

On 2015-12-01 by George

I have a one pipe steam system with a vent on the return side that never shuts off. Replaced with a new Hoffman 4C, but still the same. Turned pressure down as well. All radiators on all floors get heat....any ideas?

Question: condensate spewing water coming out of steam radiator vents

(Nov 19, 2011) Mike said:

This is a question rather than a comment. I have 9 steam radiators in my house and recentLy two of them have started spewing condensate/water from the steam vents.

I replaced those vents with new vents but the problem still exists. Any advice for next steps?

Reply:

Mike, if you are SURE that the steam vents, even the new ones, are in good shape, then I suspect that the condensate return line from your radiators may have become clogged with rust and crud.

This is even more likely if you have a one-pipe steam system as the condensate has to exit through the same valve that allows steam into the radiator.

When you can manage with heat turned off for a while you may want to disconnect one of the problem radiators from its piping and inspect for crud.

Question: more condensate spewing from steam vents

(Nov 12, 2012) Sam said:
I just replace the old steam radiator into the steam baseboard system (it's a one-pipe system).

I have 8 steam baseboard radiators (4 in living room and 4 on the second floor)in my house and recently 3 of them have started spewing condensate/water from the steam vents. I replaced those vents with new vents but the problem still exists. Any advice for next steps and how to solve this problem. Thanks !

Reply:

Sam, look for a condensate return problem that's leaving high condensate water in the radiators.

Question: cold steam radiators

(Nov 24, 2012) Andy said:
In August I had my steam boiler replaced with a Weil Mclain EG 55. My plumber has back been a few times and cannot get, in my opinion to work right.

The problem is some of radiators on the second floor do not heat.The other problem is when the thermostat reaches the correct temperature, every five minutes the furnace kicks on, runs about 35 seconds and shuts down. Anybody have any ideas.

Reply:

Andy let's start with the cold radiators: check first for a stuck radiator valve in the closed position, a stuck steam vent, or a debris or condensate clogged radiator.

Question: my tenants removed the steam vents - is that a problem?

(Dec 7, 2014) Jeff said:
my tenants have removed three of the steam vents in our house. we are planning on replacing them, but will it cause damage to anything? help!

Reply:

Jeff

I must not understand what happened here. Removing a steam vent would let steam vent continuously into a room whenever heat was turned on - or if the vent were removed and the tapping plugged the radiator would not heat.

Replacing the vents is necessary for the radiator to work. The damage that might be done would be stripping mounting threads or some other snafu.

Question: use of 1 pipe steam vents - VariValve by Heat Timers on two-pipe steam system

2015 01 22 Jennifer said:
Hello, I have the Varivalve Quick Vent / Heat Timers attached to the top return side (return pipe at the bottom) of our two steam pipe radiators.

I read above and was told by our plumber that this valve should only be with a one pipe system, though without this vent attached - loud hissing, more banging and sometimes lack of good heat occurs. We are on the top floor of a ten story apartment building and our Superintendent recommended these Varivalves.

Do you see a problem down the road using these attached vents? Is there another vent we can use? Also, often one Varivalve spits from a radiator which before water collected inside before it was pitched properly. Do we need to empty this water ourselves or should the system empty it now that it is pitched properly?

It often makes trickling water sounds inside when turned-off. Thank you very much for your help.

Reply:

Jennifer, the VariValve device you ask about is produced by Heat-Timer Corporation, 20 New Dutch Lane Fairfield, NJ 07004 USA, Tel: 973 575 4004 and website: heat-timer.com

Indeed the device is intended for improved more rapid-venting of 1-pipe steam heating systems.

It is useful to read what the company says about their own product. Quoting:

The venting capacity of radiator air vents and main line air vents used in single pipe steam heating systems has an important effect on the operation of these systems. ...

The function of the radiator air vent is to provide a means for air to be driven out of the radiator as steam enters.

At a given pressure the fill time of a radiator varies proportional to its heat capacity and inversely proportional to the venting capacity of the radiator air vent. It is possible to control the speed at which a radiator will fill with steam by installing a radiator air vent with a certain venting capacity. Used in this manner, radiator air vents are helpful in evening out the heat distribution in a building. ...

The results [of tests performed] show[ed] that the larger the vent, the more quickly you can vent a system, which lowers operating pressure requirements.

Before choosing a particular vent for your two pipe steam system radiators (the present one is not designed for that application) one would want to know more design and problem specifics for your building. With that information, a call to any of the steam vent providers or even to a savvy HVAC supplier who has a steam heat expert on staff can permit selection of the right vent.

Certainly there are plenty of choices but with just your e-note one can't specify the exact model to install.

You're right that improperly pitched radiators or anything else that interferes with condensate return to the boiler can contribute to the noise complaints and heat complaints you cite. From your description I suspect that there may be debris clogging at some of your radiators.

...

Continue reading at STEAM VENTS, 1-PIPE SYSTEMS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• STEAM VENTS - home
• STEAM VENTS, 1-PIPE SYSTEMS
• STEAM VENT TYPES, SELECTION
• STEAM VENTS, 2-PIPE SYSTEMS
• STEAM RADIATOR VENT CLEAN & TEST
• STEAM RADIATOR VENT REPAIR
• STEAM VENT TABLE, CROSS REFERENCE & SOURCES
• STEAM TRAPS

Suggested citation for this web page

STEAM VENTS, AUTOMATIC, FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING RADIATORS

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