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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 REGULATOR, DAMPER, BOOSTER
DUCT SYSTEM & DUCT DEFECTS
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
GAS 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 PLEXVENT ULTRAVENT RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
RESET SWITCH, HEATER PRIMARY CONTROL
RESET SWITCH, ELECTRIC MOTOR
RESET SWITCH, STACK RELAY
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 SYSTEMS
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
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.
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.
Leaks occur between sections of cast iron hot water or steam radiators.
The radiator may leak where sections of cast iron are bolted together, or if the radiator has rusted-through or become cracked, perhaps by freezing, you may see rust and leak stains at splits in the individual radiator sections (photo at above left) .
While an individual, accessible crack in a cast iron radiator might submit to an epoxy repair, extensive damage such as we show above usually means the heating radiator should be replaced.
Sometimes a leak at a steam radiator is not critical - you may at least make it through the heating season, or the leaking may occur only when the radiator is cold (photo, above-right, also shown at page top, of a leaky steam radiator). This is a steam condensate leak.
If you see rust stains and leak indications between radiator sections at the top of the radiator, such as in our photo (above-left), or other rust, splits, or evidence of leakage from the body of the radiator, we recommend that you ask for repair advice from your heating service company.
Leaks also occur at radiator valves, at radiator bleed valves, and at the piping fittings where valves and pipes join the radiator bottom or top.
As Carson Dunlop's sketch (left) warns, watch out for hidden structural damage or damaged ceilings below leaky radiator valves.
Continue reading at STEAM RADIATOR VENT REPAIR if your radiator leaks are at a steam radiator vent or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
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.
Also see CHEMICAL TREATMENTS, BOILER where we include a discussion of leak-stop products for hot water heating boilers & steam boilers.
Question: are steam radiator leaks dangerous?
Josh asked: 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.
R said: Today at work, a few pipes and radiators blew in some of the rooms. The leak and steam got so bad you could hardly see your hand held out in front of your face. I was in there for a while trying to find the shut off for the water and keeping the water from leaking out into the hall. I was breathing all that steam in for quite some time and I was wondering if there is anything I should be worried about. My lungs and eyes were a little irritated, but I am wondering if there could be something more. - R. 1/30/2014
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 to R about steam radiator leaks & chemical exposure:
While residential and most commercial steam systems operate at very low pressure - under 1 psi, there are some commercial systems that work at higher numbers - where an actual explosion would be potentially dangerous.
Please see CHEMICAL TREATMENTS, BOILER where we include a discussion of leak-stop products for hot water heating boilers & steam boilers, including boiler treatment products & MSDS information
Question: ammonia odor and possible radiator leaks?
(Feb 27, 2012) Thank you said:
At ODORS GASES SMELLS, DIAGNOSIS & CURE - we give diagnostic suggestions for tracking down and fixing any odor including ammonia smells. Often indeed those are found to originate in urine but there could be other sources. First find the physical source. It would be unusual for ammonia smells to come from a leaky radiator but heating a radiator may cause it to emit odors from something that was painted on or spilld onto that device.
Question: Can I fix a cracked heating radiator
(Oct 20, 2012) Rich Jankowski said:
There are stop-leak products as well as epoxy sealers that MIGHT form a temporary repair and may require application on a cool dry surface, but I'd worry about the repair not being durable.
Question: pipes and radiators blew up and released steam
(Jan 30, 2014) R said:
Today at work, a few pipes and radiators blew in some of the rooms. The leak and steam got so bad you could hardly see your hand held out in front of your face. I was in there for a while trying to find the shut off for the water and keeping the water from leaking out into the hall. I was breathing all that steam in for quite some time and I was wondering if there is anything I should be worried about. My lungs and eyes were a little irritated, but I am wondering if there could be something more.
Ugh what a mess.
I am GUESSING that you are talking about a low pressure steam system and a failure of one or more steam vents on radiators - or an actual burst steam pipe.
The immediate dangers would be steam burns, or if vision is obscured, other obvious hazards like not being able to see to get safely out of the building.
Past those immediate worries, you will want to find out what boiler additive chemicals were being used in the steam system in your building, then to look at the MSDS exposure guidelines for those products. Without that data, an immediate answer to your question would be just speculation.
As I note in the article above,
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.
Let us know what chemicals were in use and if needed I'll be glad to do some further research.
With any chemical, even distilled water, the poison is in the dose.
Question: leak at copper sweated elbow at radiator - can I use epoxy?
(Feb 13, 2014) sid jones said:
Sure, Sid , you will have temporary success if you can get the joint clean and dry long enough to bond. Try an automotive radiator repair epoxy intended to tolerate heat. Keep an eye on the patch lest it leak unattended.
Question: leaks in heating boiler after shaking, rattling, and steam came out of floorboards
(Nov 17, 2014) joints in central heating leaking said:
Hi, we just put on the heating after summer. It seemed ok, but then the boiler started shaking and rattling and there was steam coming through the floorboards. It continued a bit after shutting off the boiler (gas, 24 y old).
Then, we found a leak in a metal T-joint leading off to radiators (near boiler). We have a mixture of metal and plastic piping. The joints are all metal of course. The leak was caused by the plastic pipe coming out of the joint. We replaced the joint. Refilled system with water.
Seemed OK, but this time a leak sprunt in the bathroom (2 floors up), again, plastic pipe into metal joint. We tightened a nut that seemed loose and it hasen't leaked since. We put on the heating with just that one bathroom radiator on to test it, but the boiler got very hot, the thermostat didnt seem to cut off. We switched everything off again. We let it cool. The boiler man (on phone) said that just having one radiator on could have caused that problem, especially as the expansion tank is needing replacing (which will be done soon).
He said that if we switchen on more radiators everything should be ok. We put on the heating, switched on extra radiators, everything seemed OK, but now two new leaks have just appeared: one in the pipe going into the radiator (rad was off at the time of leak) (again plastic pipe into a metal joint). The other leak is hidden behind boarding (that I am ripping down now) but it seems to on upright pipes on the 1st floor that bring heated water to radiators directly from boiler.
This is a 100 year old+ house, and we had some new rads installed 10 years ago on a tight budget.
I would appreciate if someone could explain a likely reason why the leaks are happening. Bad workmanship ? Too high pressure in system? Water too hot in system? The expansion tank ?
Thanks in advance for any comments at all.
I forgot to say that before the boiler got very hot and the thermostat didnt cut off, I had set it to 90 degrees celsius instead of the usual 60 degrees celsius.
which was a dumb thing, and we set it back afterwards.
me again, just to say that all the leaks are in separate places and on different joints. Basement = 1 leak, 1st floor= 1 leak, 2nd floor = 3 leaks (1 x hallway rad, 1 x near bathroom rad, 1 x big pipes that bring water to top of house (3rd floor)).
Really? I can't imagine what a heating tech is thinking in saying it's ok to have steam coming up through a floor.
Leaks in stem piping are not fixed by turning on more radiators. It sounds as if you need help from a plumbing and heating contractor who is familiar with steam piping and controls.
Question: mold growth due to steam vent leaks
9 Jan 2015 Maria said:
One can't assess the harmfulness of mold by just a brief e-text but usually a large indoor mold reservoir that has grown on surfaces is at least allergenic and possibly pathogenic or toxic - depending on the genera/species and further depending on what the mold is growing-on. Large areas, more than 30 sqft. deserve professional cleaning.
You should repair or replace the steam vent that I infer from your note is failing to close when it should.
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