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AFUE DEFINITION, RATINGS
AGE of HEATERS, BOILERS, FURNACES
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER VALVE, HEATING SYS
BANGING HEATING PIPES RADIATORS
BOILER CONTROLS & SWITCHES
BOILER LEAKS CORROSION STAINS
BOILER NOISE SMOKE ODORS
BOILER OPERATING PROBLEMS
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CHEMICAL TREATMENTS for BOILERS
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CIRCULATOR PUMPS & RELAYS
DEFINITION of HEATING & COOLING TERMS
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DRAFT MEASUREMENT, CHIMNEYS & FLUES
DRAFT REGULATORS, DAMPERS, BOOSTERS
FILTERS, OIL on HEATING EQUIPMENT
FIRE SAFETY CONTROLS
FLOODED HEATING EQUIPMENT REPAIR
FLUE VENT CONNECTORS
FREEZE-PROOF A BUILDING
FUEL OIL TYPES & CHARACTERISTICS
FUEL UNIT, HEATING OIL PUMPS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GAUGES ON HEATING EQUIPMENT
HEATING COST SAVINGS METHODS
HEATING LOSS DIAGNOSIS-BOILERS
HEATING OIL PIPING TROUBLES
HEATING SYSTEM INSPECTION GUIDE
HEATING SYSTEM NOISES
HIGH EFFICIENCY BOILERS/FURNACES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH
NO HEAT - BOILER
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL PUMP FUEL UNIT
PUFFBACKS, OIL BURNER
RELIEF VALVES - STEAM TP VALVES
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOOT on OIL FIRED HEATING EQUIPMENT
SPILL SWITCHES - Flue Gas Detection S
STACK RELAY SWITCHES
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
ZONE VALVES, HEATING
Steam radiator vent disassembly, inspection, repair or replacement: using annotated photographs we disassemble an adjustable Vent-Rite NO. 51 one pipe steam radiator vent to see what's inside, to look for repairable or clean-able components, and to decide if the vent should be repaired or just replaced. Let's be clear: the least troublesome and fastest repair is to just replace a bad-behaving steam vent. But if you are determined to try cleaning a steam radiator vent or if you just want an up close look at what's inside, this article will be fun.
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When this Vent-Rite steam vent, No. 51 (that you'll have trouble even finding online) stopped working the owner had tried adjusting the vent rate using the adjustable nut on the vent bottom. But the vent no longer worked, probably because its float had developed a leak. We disassembled the unit to show the hidden parts and thus the secrets of the Vent-Rite steam radiator vent in a series of images given here.
[Click to enlarge any image]
At above left you see the Vent-Rite No. 51 adjustable steam radiator valve before I destroyed it. At above right you can see the vent opening in the valve top. This opening vents air when the radiator is cold, and as the radiator heats and the vent closes, things should get quiet and the valve stops venting. Thanks to reader Paul Ruud for discussing improved steam heat controls and thermostatically operated steam radiator valves and air vents and for providing the steam radiator vent that we disassembled for these photographs.
Some steam may vent before the valve closes. But if the vent never closes and keeps blowing steam or perhaps a mix of steam and condensate ("steam vent spitting") something's wrong. Most likely the internal valve seat is dirty or damaged and won't seal or the internal thermostatic float in the valve is defective - it's time replace the steam vent.
Watch out: steam can cause serious burns and steam condensate can be burning hot as well as a source of building water damage. Do not try to work on live steam or hot steam heating radiators and vents. Turn off and cool down the system before touching anything. These notes and photographs are for purpose of illustration. While swapping out a steam vent for a new one is simple enough that with some caution a homeowner can attempt the task, in most cases repairs on steam heating systems are best performed by a trained service technician.
At below left I give a close-up of the Vent-Rite adjustment nut that we thought might change the vent operation - but it didn't. We decided to look inside, figuring if the vent is broken and is going to be replace anyway there's nothing to lose in tearing an old one apart for the sake of science. Start by holding the vent bottom with a wrench and using a larger wrench to turn the nut I'm pinching with my fingers (below right).
Now we're getting someplace. At below left you can see the Vent-Rite top and bottom sections have been separated; a copper gasket is used at this mating joint and I've slipped the nut half-way up the vent body. If you are indulging in the fantasy that you can clean and restore this valve to service, press on, but remember I told you to just go ahead and buy and install a new one on the radiator before messing with the old valve.
At above right I'm holding the vent adjustment nut with pliers and you can see that if it did anything, that nut would move the plunger in or out to press more or less against the bottom of the Vent-Rite's internal float. At below left you can see the plunger working end. At below right I'm showing how the adjustable plunger, by moving in or out of the vent body, would make the vent's internal float start at a higher or lower position inside the vent body. Why we care about the float position will be shown next.
OK so here's how this vent works to open or close the steam vent on a radiator. If the float rises its tapered point pushes against an opening in the top of the valve body to stop steam from escaping. If the float falls it opens the vent. The vent will close either thermostatically (it gets hot and the float pushes up and closes the opening in the vent top) or by floating upwards should actual condensate (water) fill the float body. Just follow the yellow arrow.
Now we know why a steam vent might "spit" water: its top opening is not closing fully AND the radiator has a lot of condensate inside.
At below left we show a close-up of the actual steam radiator vent float and its tapered tip.
At above right we show the steam radiator vent disassembled but with its parts in order - more or less. From the bottom up is the adjustment nut, the valve base containing its internal plunger, gasket, vent float, vent top body that includes a vent orifice at its top, and a large ring nut that secures the vent body top to its base.
Bottom line on steam radiator vent repair versus replacement
You might want to try cleaning the valve seat or float pin in a steam radiator vent but really it's not worth the time and trouble, especially since there's a good chance that if the valve no longer opens or closes when it should it's the float itself that's at fault.
In an emergency you might try to take apart and clean a steam radiator vent as we did here, usually you won't.
Given the trouble of cleaning and reassembling and reinstalling the valve, then bringing up the heat to watch the valve to see if it works, the disappointment when it doesn't, and the muttering, to me it makes sense to just go ahead and replace the steam vent with a new unit.
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