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SAFETY, HEATING INSPECTION
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SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
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Radiator valve inspection & troubleshooting: here we explain the use, adjustment, diagnosis & repair of hot water or steam heating radiator valves & steam vents to control heat output from individual radiators.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Guide to Using, Adjusting, Diagnosing & Fixing or Replacing Hot Water or Steam Radiator Control Valves & Vents
Traditional "Manual" Radiator Valves
Radiator valves are opened to allow hot water or steam to enter and heat a radiator, or closed to turn off or reduce heat output from the radiator. By "manual" radiator valve we mean that you have to turn the valve open or shut yourself. We discuss automatic (thermostatically controlled radiator valves and other radiator controls below.
At above left is a top-fed two pipe steam radiator at Google Headquarters in New York City.
This website answers most questions about all types of heating systems and gives important inspection, safety, and repair advice. If you don't know what kind of heat your building uses, we explain how to figure out the answer at HEATING SYSTEM TYPES. If your heating system is not working properly, see NO HEAT - BOILER or NO HEAT - FURNACE.
If your heating system radiators won't get hot, for hot water radiators or convector heat, see COLD HOT WATER BASEBOARD / RADIATOR; for steam heat see COLD STEAM HEAT RADIATORS for help in diagnosing the problem.
If your heat is provided by baseboards there will not normally be individual shutoff valves at those devices, but if your system uses one circulator and provides multiple heating zones (and thermostats) there will be zone control valves (usually near the boiler) that are opened or closed by the room thermostat(s). Cold heating baseboards are discussed at AIRBOUND HEAT SYSTEM REPAIRS.
Which Way to Turn the Radiator Valve
If your heat is provided by individual hot water radiators or convector units, usually there is a control valve at each radiator or convector. Make sure that the control valve at the heating radiator is "open" or "on". Usually turning a radiator valve "clockwise" or "down" closes the valve (turns the heat At COLD HOT WATER BASEBOARD / RADIATOR we include links to additional detailed articles that will help you correct a problem with heating baseboards or radiators that are not working:
Watch out: don't use excessive force to try to turn a "stuck" radiator valve. First, you may be trying to open a valve that is already in its fully-open position. Second, the valve may actually be jammed. Excessive force can break the valve or even cause a leak. If the valve won't turn at all counter-clockwise towards "open", try turning it the other way - clockwise, towards "closed". If the valve now turns you'll know it was already in its open position.
Watch out: even if the radiator valve appears to be "open" - that is, turned fully counter-clockwise, if the radiator valve stem is broken internally you may be just turning the knob but the valve may be staying closed inside. If your radiator valve turns too easily or if it does not appear to raise (opening) or lower (closing) when turning, and especially if turning the valve makes no difference in the behavior of the radiator, the valve stem may be broken. (First check for air bound radiators or if your heating system uses steam, check for a steam vent that is not opening.)
Usually while turning a radiator valve to from "closed" to "open" position, if you look closely at the valve stem - the metal rod or shaft extending below the knob you are holding, and extending into the body of the valve itself - you'll see that as you "open" the valve the stem gets "longer" and often a less-oxidized, shiner part of the valve will become exposed as it moves upwards from having been inside the valve body.
That's a great way to convince yourself that yes, the valve is probably opening internally too, you're not just turning the knob. If the valve body has broken loose from the valve stem, that's an internal problem you can't see, but turning the radiator valve knob, even if it rotates, will not open a broken, stuck, frozen valve.
If only some of your hot water radiators, hot water heating convector units, or hot water baseboard heating sections are not getting hot and the radiator valve is open, see AIRBOUND HEAT SYSTEM REPAIRS (hot water heat) or if a steam radiator valve is open but the radiator is still cold, the steam vent may not be working. See RADIATOR STEAM VENTS and also STEAM HEATING SYSTEMS for details.
Hot Water Heat Radiator Valves
Steam Radiator Control Valves
If your heating system uses steam radiators or steam convectors see COLD STEAM HEAT RADIATORS for help in diagnosing and fixing steam radiators that won't get hot. Excerpts from that article are found below.
Manually Setting the Radiator Valve
On hot water heating systems and two-pipe steam radiator heating systems you can adjust the radiator valve to:
If your hot water radiator is too hot or the room is too hot, you can partially-close the radiator valve.
If your hot water radiator is too cold, be sure that the valve is open and that the radiator is not air bound. Details are at COLD HOT WATER BASEBOARD / RADIATOR
If your steam radiator is too cold be sure that its supply valve is open. If it's a one pipe steam heat system (only one pipe comes to each radiator), be sure that the steam vent is working (you should hear it hissing when steam is rising in the system). Details are at COLD STEAM HEAT RADIATORS.
If you steam radiator is too hot in a two-pipe steam system, according to the U.S. DOE,
If your steam heating system pipes are noisy see BANGING HEATING PIPES RADIATORS wHere we explain steam condensate return problems that can cause banging clanging pipes.
There are additional methods for automatically controlling the heat output from individual heating radiators, for both steam and hot water heat: thermostatically controlled radiator valves and adjustable or thermostatically controlled steam vents. We discuss these controls beginning at Automatic or Thermostatically Controlled Radiator Valves - TRVs.
The radiator control valve opens or shuts to allow hot water or steam to enter and heat the radiator. An automatic or thermostatically controlled radiator valve allows you to set the desired room temperature. The valve will automagically open or close to attempt to control room temperature to the desired level. Keep in mind that with any heat control installed right at the radiator, the control will be sensing temperature in that location, not across the room, so some experimenting to find the best setting will be needed.
Guide to Choosing & Installing Adjustable or Thermostatically Controlled Steam Vents to Control Steam Heat
Types & Properties of Steam Radiator Vents
Each of these steam vent types is discussed below.
By controlling the rate at which a steam radiator gets hot, adjustable steam vents are a key instrument for balancing steam heat in a building.
Watch out: although adjustable steam vents can control the rate at which a steam radiator gets hot, these adjustable air vents are not identical in function and application nor is heat control using adjustable steam vents identical with that provided using thermostatically controlled radiator valves.
Thermostatically-controlled no-float steam vents
Float-type steam vents
As we introduced above, float type steam vents use a water+alcohol-filled float inside the steam vent heats, rises, and closes the vent as the radiator heats. The float also rises to prevent water from spitting out of the vent should condensate rise inside the radiator or vent. Rust or sediment can clog the float vent opening and interfere with its proper operation. Excessive steam pressure can also prevent the vent from operating properly.
Adjustable steam vents
Also as we introduced above, manually adjustable steam vents operate similarly to the float-type steam vents described above, but add the feature of adjustable air vent opening size so that the air venting rate can be better matched to the radiator size. (Larger steam radiators need a larger air vent opening.)
Examples of manually adjustable vent-rate steam vents include: Hoffman Model 1A (Part No. 401422) adjustable air valve with 6 settings (1-slow to 6-fast venting); VariValve® Quick-Vent. Those vents are designed for traditional steam radiators. If your steam heat is by a steam convector unit, different steam vents are required, such as the Hoffman Specialty Model 1B (Part No. 401425). Additional steam vents are listed at references below.
Adjustable Thermostatically-operated steam vents
Thanks to reader Paul Ruud for discussing improved steam heat controls and thermostatically operated steam radiator valves and air vents.
Frequently Asked Questions (FAQs) about hot water heat radiator valves & steam heat radiator valves
Question: where do steam pipes enter steam radiators: top, bottom, or both?
I had a question about the article at RADIATOR VALVES & HEAT CONTROLS.
I’m looking at the sub-section “Types of Radiator Valves: Hot Water vs. Steam” and here is a copy of the 1st paragraph; the writing becomes nonsensical and near the end and it may turn out that some of the information is incorrect: “In our photo at left you can see not only the radiator control valve, but lots more information: we can conclude that this is a hot water heating system, not a steam heat system because first, the valve is mounted at the top of the radiator (water, not steam - steam enters at a radiator bottom but sometimes so does not water; the reverse is never true).”
I was trying to make sense of what was written and discovered another article (which also has nonsensical syntax- it must be hard to describe these hot water and steam heating systemsJ) which seems to indicate that in fact steam DOES often enter a radiator at the top. At this point I am just lost. We don’t have many residential systems with radiator systems (steam or hot water) so I am trying to edumacate myself but don’t have anything in front of me to compare what I think I understand.
Kind Regards, -Doug
Reply: Up-feed - Down-feed, One-pipe - Two-Pipe Steam Piping & Radiators - What's the Difference?
Doug, the other page (not at InspectApedia) that you gave provides information from Dan Holihan - probably the most-expert fellow alive when it comes to steam heating systems. Dan's text includes these two statements:
Questions & answers or comments about using, adjusting, & repairing radiator control valves and vents for both hot water and steam heat systems
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.