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PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
AGE of PLUMBING MATERIALS & FIXTURES
AIR DISCHARGE at FAUCETS, FIXTURES
ANTI SCALD VALVES
ANODES & DIP TUBES on WATER HEATERS
BACKUP PREVENTION, SEPTIC
BACKUP PREVENTION, SEWER LINE
BACKWATER VALVES, SEWER LINE
BATH & KITCHEN DESIGN GUIDE
CHEMICAL CONTAMINANTS in WATER
CHLORINE IN DRINKING WATER
DEBRIS in WATER SUPPLY, Water Heater
DEPTH of SEPTIC TANK
DRAIN & SEWER PIPING
FAUCETS & CONTROLS, KITCHEN & BATH
FAUCETS, OUTDOOR HOSE BIBBS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOR DRAIN / TRAP ODORS
FLUSHOMETER VALVES for TOILETS URINALS
GAS PIPING, VALVES, CONTROLS
GALVANIC SCALE & METAL CORROSION
HARD WATER - SOFTENERS
HEAT TAPES, Heat, Insulation prevent Freeze-Up
LEAD POISONING HAZARDS GUIDE
LEAD IN DRINKING WATER, HOW to REDUCE
METHANE GAS SOURCES
MIXING / ANTI-SCALD VALVES
MUNICIPAL WATER PRESSURE IMPROVEMENTS
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER
ODORS, SEPTIC or SEWER
ODORS SEWER GAS in COLD WEATHER
ODORS, SULPHUR SMELL SOURCES
ODORS, URINE REMOVAL
PIPING IN BUILDINGS, Clogs Leaks Types
PLUMBING FIXTURES, KITCHEN, BATH
PLUMBING NOISE CONTROL
PLUMBING VENT DEFINITIONS & CODES
PLUMBING VENT DEFECTS & NOISES
PUMPS, WATER REPAIR
RELIEF VALVE LEAKS
RELIEF VALVES - TP Valves on Boilers
RELIEF VALVES - STEAM TP VALVES
RELIEF VALVES - Water Heaters
RELIEF VALVES - Water Tanks
REPAIR BURST LEAKY PIPES
SEPTIC METHANE GAS
SHUTOFF VALVE LOCATION, USE
SULPHUR & SEWER GAS SMELL SOURCES
SWEATING (CONDENSATION) on PIPES, TANKS
TOILETS, INSPECT, INSTALL, REPAIR
WATER, WELLS, WATER TANKS: TESTING GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMPS & TANKS
WATER SOFTENERS & CONDITIONERS
WATER SOURCE ALTERNATIVES
WATER SUPPLY & DRAIN PIPING
WATER SHUTOFF VALVE LOCATION, USE
WATER SHUTOFF VALVE, WELL PUMP
WATER TESTS, CONTAMINANTS, TREATMENT
WELLS CISTERNS & SPRINGS
WINTERIZE A BUILDING
Condensation on plumbing pipes, tanks, toilets: here we explain the causes, significance, and cures for condensation or "sweating" on plumbing system components like pipes, water tanks, and toilets. A certain amount of moisture condensation on building plumbing systems is normal in areas of warm humid weather and cold or chilly incoming water supply. But as we explain here, excessive condensation on plumbing systems can cause costly problems in buildings. The articles at this website will answer most questions about plumbing drain, waste, vent, water supply & septic systems.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Related articles: HUMIDITY CONTROL TO PREVENT MOLD. Also see DEW POINT TABLE - CONDENSATION POINT GUIDE for an explanation of dew points and indoor humidity in buildings, and see MOISTURE PROBLEMS: CAUSE & CURE and HOUSEWRAP AIR & VAPOR BARRIERS and VENTILATION in BUILDINGS.
Our sweating toilet tank photo (left) illustrates where condensation may form on the tank of a toilet that is in frequent use during hot humid weather, or on a toilet whose flush valve leaks, allowing the toilet to "run" continuously.
Condensation, the collection of airborne moisture on cool surfaces can happen anywhere in the plumbing system where components are cooler than surrounding, moist air. Common places where we see condensation or "sweating" include toilet tanks, cold water pipes, and water storage or water pressure tanks.
Carson Dunlop Associates in their Home Reference Book point out that in some homes, the cold water piping is insulated to avoid sweating of pipes.
Our photo (left) shows a close-up of condensation on the exterior of a steel water pressure tank..
This ‘sweating’ can be annoying, and if allowed to continue, can damage ceilings, floors, furniture or storage below. Condensation that drips off of these locations can even lead to building rot, insect attack, or to the need for a costly mold cleanup job.
So Do Water Pipes Actually "Sweat" in buildings?
No. Pipes and tanks don't literally "sweat". "Water pipes do not "sweat" as people say - water is not exuding out of pores in the pipe. Water is condensing from moist air onto the surface of the cold water pipe. Insulate your cold water pipes to avoid condensation and drips onto the floor. What people popularly refer to as "sweating pipes" really is airborne moisture that is condensing out of humid air onto a cool pipe, tank, or other surface.
Where Does Condensation Occur on Plumbing Systems?
Our photo (left) illustrates that "sweating" cold water pipes can be a serious hazard. These cold water pipes are dripping condensate (red arrow at left) right into the electrical panel (down-pointing red arrow at left), risking corrosion of the circuit breakers and other electrical components. Corrosion can lead to failure of a breaker to trip in event of an over-current. So water pipe condensation could actually contribute to a building fire! Details are at CORROSION in ELECTRICAL PANELS.
What Causes Condensation on Plumbing System Components like Pipes, Tanks, Toilets?
Why does water condense on your cold water pipes overhead in the basement before it condenses on the steel Lally columns supporting your main girder? It's because the cold water pipe surfaces are colder than the Lally column surfaces exposed to the same moisture-laden air.
When cold water (at 40 deg.F.) is running through the water pipe, the pipe surface is cooled to a lower temperature (40 deg.F.) than that of the Lally column (perhaps 55 deg.F. or higher in a typical residential building basement).
When the temperature of air reaches the dew point (a function of the combination of a particular air temperature and the amount of moisture in the air), moisture condenses out of the air onto nearby cooler surfaces. See DEW POINT TABLE - CONDENSATION POINT GUIDE for more details.
[Note: Another definition of "sweating pipes" is used by plumbers to refer to the process of soldering copper plumbing joints.]
Condensation May Indicate Plumbing Leaks or Private Well Piping Problems
Hidden water supply pipe leaks: similar to the case above, a plumbing fixture with a running faucet is pretty obvious. But a hidden supply piping leak may be dripping or leaking into a building wall cavity or even outside or underground.
If the cold water pipes in your building are wet with condensation even though you think no water has been running for hours, there may be a hidden plumbing leak. A great time to check for this condition is on first arising in the morning, before plumbing fixtures have been used.
Our photograph of stains on an interior wall (left) is an example of indoor stains caused by moisture on building plumbing pipes.
Private well piping or well problems: intermittent cycling of a well pump when no water is being run is often a sign of either a running plumbing fixture in the building, or a leak in the well piping itself. If you see condensation on water piping entering the water pressure tank and hear intermittent well pump cycling for no apparent reason, further investigation is warranted. See INTERMITTENT CYCLING WATER PUMPS and WELL PIPING LEAK DIAGNOSIS.
Indoor stains in ceilings or walls, flooring damage, and even hidden mold are all problems that can be caused by hidden plumbing leaks or by condensation on cold water piping where it passes through building cavities.
Insulate Cold Water Piping
For at least two reasons, that of energy efficiency and to prevent moisture drips and possible mold growth inside basement ceiling cavities, you might want to insulate your hot water and heating pipes in a basement as well, though in some conditions we are so desperate to warm and dry a problem area that we deliberately leave the hot water and heating pipe insulation off of those pipes so that we can steal some of their heat to warm and dry an area.
Carson Dunlop suggest that if a basement is to be finished, the cold water piping above the ceiling should be insulated.
Foam insulating tubes that snap around plumbing piping are widely available and work very nicely for this purpose. We advise against wrapping pipes in fiberglass insulation.
Insulate the Water Pressure Tank?
Where a water pressure tank is located in a finished basement or similar area, having puddles of condensate on the floor around the water tank can be a problem. If you have made sure that there are no plumbing leaks or well pump short cycling problems that are keeping the water tank cold and subject to condensation too much of the time, insulating the water tank with an insulation blanket may be helpful.
Watch out: we have inspected properties where the water pressure tank was located in a finished basement, enclosed in a closet, and surrounded with fiberglass insulation. Wetting fiberglass insulation is inviting a hidden mold contamination problem. Insulating such "closets" with solid foam insulation may be a more mold-resistant approach. See INSULATION MOLD for details.
Insulate Toilet Tanks?
Some toilet models currently sold include an insulated toilet tank and may be appropriate if you live in an area where weather is hot and humid for much of the year, as toilet tank condensation can be a problem even if the toilet is not leaky or running. But before going to the cost and trouble of changing out a toilet tank or trying to insulate the exterior of the tank, make triple sure that your toilet is not leaky and running.
Fix Plumbing Leaks
Find and fix running toilets, hidden plumbing leaks, well piping problems or municipal water piping problems that we listed earlier.
Use a Dehumidifier, Add Heat, Increase Air Circulation
Our preferred method for reducing condensation on plumbing pipes, tanks, toilets indoors is to reduce the level of indoor humidity to an appropriate level using either a local portable dehumidifier, or the building's central air conditioning system. See HUMIDITY LEVEL TARGET for details.
In some circumstances increasing the air circulation around a condensation-prone water tank can reduce the total quantity of condensation, at least if the condensation is from normal use and not from a plumbing leak. In some commercial installations and in a few private homes where condensation people add heat where spot condensation is a particular problem.
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