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AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC HEAT, DIAGNOSIS, REPAIR
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
LP & Natural Gas Safety Hazards
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC HEATER VENT
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
Heating radiator leak troubleshooting: This article describes how to find and fix leaks in hot water heating radiators. We describe the types and locations of leaks found on heating radiators: hot water, steam, cast iron, heat convectors, baseboard heat, electric heating convectors. Our page top photo shows a common point of leakage on cast iron radiators, between abutting radiator sections near the bottom of the unit. This article series answers most questions about all types of heating systems and gives important inspection, safety, and repair advice. In addition to cast iron radiators using hot water or steam as a heat source, we describe two other very common hot water heat distribution methods below.
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Obviously, first look at the floor around each heating component to see if you see water stains or water damage. (Water damage can occur at steam radiators too, as condensate could be leaking at the condensate return pipe fittings.)
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.
On heating systems using hot water baseboards, leaks can occur anywhere in the piping system, including at air bleeders located at the ends of baseboard sections, at couplings or elbows in the piping system, or where freezing has cracked or burst a heating baseboard pipe.
Our photo of a leaky heating baseboard (above left) shows that prolonged leaks may rot carpeting (leaving an obvious leak clue once someone vacuums up the ruined carpet at this spot) and may also cause hidden damage to the subfloor or even the structure. Or perhaps a mold problem may result.
Our baseboard piping leak photo (above right) shows how freezing pipes may cause separation at a solder joint instead of actually bursting the piping. In the case shown, the original solder joint had been poorly made, so this was a weak point that broke first.
Leaks at heating baseboard air bleed valves are shown at AIR BLEEDER VALVES. If your heating baseboards are not in fact getting warm when your thermostat is calling for heat and the boiler is indeed running, see AIRBOUND HEAT SYSTEM REPAIR
Also see WINTERIZE A BUILDING for examples of freeze-burst copper forced hot water heating piping in a baseboard heat system.
Frequently Asked Questions (FAQs) about hot water or steam radiator troubleshooting, installation, or repair
Question: repair a pinhole leak in copper baseboard
Im a journeyman plumber and I know how to braze but I'm not sure how to go about repairing a pinhole leak in a copper hot water baseboard heater. Obviously it has to be dry before I can braze it but how do I drain it and once repaired how do I properly fill it up with water and bleed the excess air?
Reply: solder repairs of small leaks in copper heating baseboard piping
The proper repair of a pinhole leak in copper piping would be soldering not brazing. But you'll most likely need to remove the water from the baseboard heater first. Or one can cut out a bad section of tubing or piping and solder in a short section with unions and copper piping of the same diameter. Be sure to properly sand and prep the copper pipe surfaces, remove any burs, and use a soldering paste or flux to assure a good solder connection.
Watch out: often the presence of a single pinhole leak is an indicator of more trouble ahead. Corrosion, or too-thin or defective copper piping may be prone to developing multiple leaks. I'd go ahead and patch or repair the present leak, but I'd keep an eye on the building heating distribution piping and baseboards for more leaks down the road.
Question: are steam radiator leaks dangerous?
I have an old one pipe steam radiator that has a small crack about 8 inches up. It drips a bit but my concern is the steam. Is this dangerous to have expelled into the air as far as breathing quality. I am not sure If it is a health issue. I have some concerns about having It replaced with a cheap one from china. Thanks so much for your help. - Josh (also by email) J.F. Thank you so much for your help.
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with leaky radiators, including possible hidden damage from prior or long-standing leaks.
That said, here are some things to consider:
Follow-up comment: Harmful chemicals in steam from steam boilers?
Thanks for the quick reply Daniel. I was unsure if chemicals were commonly used in the w
Reply: List of common chemicals found in steam boiler water treatment compounds and reference to their MSDS information
Thanks for the clarification
Indeed some steam heat systems, usually commercial, may contain anti frothing agents and anti corrosive or anti scale agents that remove oxygen from the water and control boiler water pH, or to keep minerals such as calcium and magnesium in suspension (glycerin, Sulfites to remove oxygen, prevent corrosion, alkalinity boosters to reduce the pH and thus control corrosion, phosphates and polymers to keep minerals in suspension and thus reduce scale formation, and amines to "boost condensate" to further reduce corrosion)and it would be reasonable to be worried about some of those chemicals in the boiler water itself.   ]
Carbonic acid (H2CO3) formation in heating boilers and the resultant need for boiler water treatment is discussed at HEATING SYSTEMS
Check with your boiler service company and take a look at the boiler service tag - let me know if any additives were used in your system (unlikely in residential steam boilers) and we can research further by reviewing the MSDS for those products.
Corrosive liquids used in some treatment compounds are skin, lung, and eye irritants (and considered unlikely to be ingested), but you would not expect to find these being released at harmful levels into occupied space from a steam radiator steam leak, since the same steam is also vented quite normally through steam radiator vents during normal system operation.
Try JB-Weld Epoxy for Cracked Home Heating Radiator Repairs?
Some readers have reported and we consider that it may be possible to repair a small crack or leak in a cast iron radiator using an expoxy product. One source to consider (we have not tried this) is JB-Weld, a producer of a range of epoxy and sealant products sold most readily in automotive supply stores and some building supply stores. firstname.lastname@example.org.
However if the radiator leak or crack is not in a location at which you can thoroughly clean and prep the surface, we're doubtful about this approach.
Questions & answers or comments about diagnosing & fixing leaks in hot water or steam heat radiators.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.