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PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR

AGE of PLUMBING MATERIALS & FIXTURES
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions

BACKDRAFTING HEATING EQUIPMENT
BACKUP PREVENTION, SEWER LINE
BATH & KITCHEN DESIGN GUIDE
BATHROOM MOLD
BATHROOM VENTILATION
BIOLOGICAL POLLUTANTS
Bisphenol-A, BPA
BLEVE EXPLOSIONS
BLOCKED DRAIN REPAIR METHODS
BOILERS, HEATING
BUILDING SAFETY HAZARDS GUIDE

CARBON MONOXIDE - CO
CHECK VALVES
CHEMICAL CONTAMINANTS in WATER
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHINESE DRYWALL HAZARDS
CARBON MONOXIDE - CO
CHECK VALVES
CHEMICAL CONTAMINANTS in WATER
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CARBON MONOXIDE - CO
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHLORAMINE / CHLORINE Tests
CHLORINE IN DRINKING WATER
CHLORINE in WATER, HOW TO TEST FOR
CHLORINE IN SEPTIC WASTEWATER
CISTERNS
CLOGGED DRAIN DIAGNOSIS & REPAIR

DRAIN a WATER HEATER TANK
HEATING SYSTEMS
HOT WATER SUPPLY

MIXING / ANTI-SCALD VALVES
NO HEAT - BOILER / FURNACE DIAGNOSIS

PLASTIC HEATER VENT

SEWER GAS ODORS

WATER HEATERS
AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
  Electric Shower Heaters
  High Efficiency Water Heaters
  Indirect-fired Water Heaters
  Instantaneous Water Heaters
  Multiple water heaters in parallel
  Multiple water heaters in series
  Range Boiler Water Heaters
  Side Arm Coil Water Heaters
  Solar Water Heaters
  Tankless Coil for Hot Water
  Tankless Water Heaters
AIRBOUND HEAT SYSTEM REPAIRS
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
APPLIANCE EFFICIENCY RATINGS

CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHLORAMINE / CHLORINE Tests
CHLORINE IN DRINKING WATER
CHLORINE in WATER, HOW TO TEST FOR
CHLORINE IN SEPTIC WASTEWATER
CISTERNS
CLOGGED DRAIN DIAGNOSIS & REPAIR
CLOGGED SUPPLY PIPING

DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK

ELECTRIC WATER HEATERS
FLOODED WATER HEATER REPAIR

GAS FIRED WATER HEATERS
  DRAFT HOODS - gas fired
  Gas BTUH & Cubic Feet
  Gas Conversion LP Natural Gas
  GAS PIPING, VALVES, CONTROLS
  SOOT on OIL FIRED HEATING EQUIPMENT
  SPILL SWITCHES - Flue Gas Detection

GAS PIPING, VALVES, CONTROLS

HOT WATER IMPROVEMENTS
HOT WATER PRESSURE EXPANSION RATE
HOT WATER QUANTITY IMPROVEMENT
  Alternative Hot Water Sources & Methods
  Anti-Scald Valves & Hot Water Quantity
  CLOGGED PIPING & Hot Water Flow
  Extra Tanks to Increase Hot Water
  Insulate Hot Water Piping
  Insulate Hot Water Tank?
  Larger Diameter Water Supply Piping
  Tankless Coil Hot Water Increase
  Temperature of Hot Water is Too Low
  Water pipe clog diagnosis
  Water pipe clog repair guide

HYDROGEN SULFIDE GAS

INDIRECT FIRED WATER HEATERS

MANUALS & PARTS GUIDES - HVAC
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER

OIL FIRED WATER HEATERS
  DRAFT MEASUREMENT, CHIMNEYS & FLUES
  DRAFT REGULATORS, DAMPERS, BOOSTERS
  OIL BURNERS
  OIL BURNER NOISE SMOKE ODORS
  OIL TANK PIPING & PIPING DEFECTS
  OIL TANKS

MIXING / ANTI-SCALD VALVES
PIPING IN buildings, Clogs Leaks Types
PLUMBING FIXTURES, KITCHEN, BATH
RELIEF VALVES - TP Valves on Boilers

RANGE BOILERS
RELIEF VALVES - TP Valves on Boilers
RELIEF VALVES - Water Heaters
RELIEF VALVES - Water Tanks
SEWER BACKUP PREVENTION
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SCALE REMOVAL, WATER HEATERS

SOLAR ENERGY SYSTEMS
SOLAR HOT WATER HEATERS

TANKLESS COILS

TANKLESS WATER HEATERS

Temperature Pressure Relief Valves - Water Heaters
TIMERS for ELECTRIC WATER HEATERS

TRAPS on PLUMBING FIXTURES

VALVES, PLUMBING
VENT PIPING

WATER CONTAMINANT LEVELS
WATER FILTERS
WATER HAMMER NOISE DIAGNOSE & CURE

WATER HEATERS
WATER HEATER ALTERNATIVES
WATER HEATER ANODES, DIP TUBES
WATER HEATER AIR INLET
WATER HEATER DEBRIS FLUSH
WATER HEATER DRAIN PROCEDURE
WATER HEATER FLUSH PROCEDURE

WATER HEATER NOISES

WATER HEATER PROPERTIES
  Electric, Gas, Oil Water Heater Efficiency
  Water Heater Life Expectancy Comparisons
  Water Heater Operating Cost Comparisons
  Water Heater Purchase & Maintenance Costs
  Water Heater Water Quantity Comparisons
  Water Heater Recovery Speed Comparisons
  Water Heater Safety Comparisons

WATER HEATER SCALE - De-Liming Procedure
WATER HEATER SCALE PREVENTION

BOILERS, HEATING
CARBON MONOXIDE - CO
FURNACES, HEATING
HEATING SYSTEMS
HOT WATER SUPPLY
NO HEAT - BOILER / FURNACE DIAGNOSIS

PLASTIC HEATER VENT
PLUMBING

SAFETY, HEATING INSPECTION

More Information

Old gas fired water heater with range boiler in background (C) Daniel FriedmanGuide to Gas-fired Hot Water Heaters - Inspection, Diagnosis, & Repair
InspectAPedia®  -    

  • LP or Natural Gas Fired Water heaters: how to inspect, test, adjust, repair
  • How to choose among types of hot water heaters
  • No Hot water? how to get more hot water flow, quantity, performance from your water heater
InspectAPedia offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.

The articles at this website will answer most questions about electrical water heaters as well as many other building plumbing system inspection or defect topics. This page contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.

Our photo above shows an antiquated gas-fired water heater (white unit in left foreground) and just for fun, we've included an old Range Boiler water heater hidden back in the corner (silver unit behind the gas fired water heater).

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Inspection, Diagnostic, & Repair Guide to Electric Hot Water Heaters

Schematic of a gas fired water heater (C) Carson Dunlop

How do we Identify a Natural Gas or LP Gas-fired Water Heater?

The sketch at left shows the basic components of a gas-fired water heater and is provided courtesy of Carson Dunlop. It's easy to identify a gas-fired water heater:

if you can find your water heater tank at all, take a look at what pipes and wires are connected to it.

A gas-fired water heater will have two water pipes connected to it (cold-in and hot out), and a pipe or in some jurisdictions a flexible copper tube bringing LP gas or natural gas to the heater.

The gas fired water heater will have a flue or "chimney" which vents combustion gases outside, either by connection to an existing chimney or flue, or in the case of power-vented and high efficiency gas water heaters, flue gases may be vented outdoors by a plastic pipe.

You'll also see a thermostat and gas valve control which combines a temperature setting with a safety device that senses the presence of a gas flame. (If there is no flame the control will turn off the flow of gas to the appliance.) Lots of newer gas fired water heaters will also include a flue gas spill switch at the draft hood atop the water heater.

But watch out: sometimes an electric water heater is installed as an additional or backup hot water source, so you'll also want to see if you have other hot water heating equipment installed, such as a Tankless Coil for Hot Water.

Here are a few things to check on your gas-fired water heater:

(WARNING: This is an INCOMPLE LIST and important water heater inspection topics may be omitted as we're working on this section. If you have comments, questions, suggestions, Contact Us.)

Gas Fired Water Heater Chimney & Venting Defects

Check for proper exhaust venting of combustion products from your gas fired water heater.

Old chimney warnings: Where a gas fired water heater is connected to a large masonry chimney it may not be able to develop sufficient draft to vent properly. The result could be dangerous spillage of flue gases into the building.

Shared flue warnings: Where a gas fired water heater shares a chimney with other heaters such as a boiler, venting of the water heater's combustion products may be unreliable, depending on whether the other larger appliance is operating or not.

Some jurisdictions do not permit sharing a flue between a gas fired appliance and other fuels such as oil; other communities may permit shared flues provided the gas vent is properly connected: usually entering the main chimney flue below rather than above the more powerfully-venting oil fired appliance.

Hair clogged gas water heater vent hood (C) Daniel Friedman

Blocked or missing gas heater draft hood warning: on occasion we find items stored atop of a gas fired water heater, or as in this photo, debris which has been drawn into and around the draft hood, preventing safe venting of combustion gases from the building.

At the property where we took this photo, the occupants had kept a number of large, hairy, shedding dogs in the basement utility area and their hair had clogged the water heater vent.

We discuss gas appliance draft hoods further at DRAFT HOODS - gas fired.


Spillage at a gas water heater draft hood (C) Daniel Friedman Burn marks on top of a gas fired water heater (C) Daniel Friedman

Check for evidence of flue gas spillage at the gas fired water heater's draft hood by looking for burn marks, rust, soot or debris.

The melting pipe insulation in our photo at left indicates that flue gas has been spilling from this water heater.

The burn marks in our right hand photo show a serious flue gas venting problem with the gas fired water heater.

Flue gas spill switch not installed (C) Daniel Friedman

If flue gas spillage detection sensors (spill switches) are required in your jurisdiction they must be properly installed, usually at the gas vent draft hood.

(On some gas fired appliances such as furnaces or boilers additional sensors may be installed at or close to the gas burner as well.)

Our photo at left shows that we found a flue gas spill switch lying atop of the gas fired water heater - it had never been installed.

Dangerous carbon monoxide warning & soot from gas appliances: If any gas fired appliance is producing soot it should be shut down immediately, inspected, and repaired before use. Soot from a gas appliance, or high levels of indoor moisture condensation that are traced to that appliance, are indicators of improper venting of combustion products and risk the production of dangerous, potentially fatal carbon monoxide gas.

Other Gas Fired Water Heater Defects

Check for proper combustion air supply for your gas fired water heater. Failure to provide sufficient combustion air is dangerous: lack of adequate combustion air will cause a gas burner to produce dangerous, potentially fatal carbon monoxide gas.

Leaks at a hot water heater (C) Daniel Friedman

Check the pressure and temperature relief valve on your water heater: look for evidence of corrosion, leaks, improper installation, etc. A missing, modified, blocked, or leaky pressure relief valve is extremely dangerous and can lead to a catastrophic BLEVE boiling liquid vapor explosion that can cause severe damage or even fatalities at a building. See RELIEF VALVES - TP VALVES

Look for evidence of leaks in the hot water tank, or mechanical damage, or improper installation. For example most water heaters are intended to be installed in a vertical position. Installing a hot water tank horizontally or in a hole in a crawl space is likely to cause early failure of the heater, violate the manufacturer's guidelines, and may be dangerous.

In our photo at left an oil-fired water heater and an indirect-fired water heater are installed in tandem. That puddle on the floor needs investigation.

Check the settings of the water heater temperature: See Temperature of Hot Water is Too Low. On a gas fired water heater the heater temperature control is usually on the gas valve itself.

Look for insulation that has been improperly added to the water tank - it may be unsafe. See Insulate Hot Water Tank?

Gas fired water heater, antique Barcelona Spain Gaudi Apartments (C) Daniel FriedmanCheck the water piping and control valves connected to the water heater for leaks, support, and for proper location of shutoff valves. An improperly installed shutoff valve on a water heater can be very dangerous, risking an explosion. Usually the "hot water tank shutoff valve" is installed only on the cold water pipe coming into the water tank.

There should be no shutoff valve installed on the hot water line leaving the water tank.

The antique gas-fired water heater shown at left is installed in the Gaudi Apartments in Barcelona, Spain. By modern standards this is an unsafe water heater.

Check for Gas Leaks: In addition to a characteristic odor that you may smell associated with LP or natural gas leaks, a prolonged gas leak may leave telltale dark stains on the gas piping or control. See Gas Leak Detection for details.

If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.

Vacuum relief valves are required at water heaters in some communities, to protect against collapse of the water storage tank and to prevent backup of hot water into the cold water piping should cold water pressure drop. Here is Carson Dunlop's sketch of a vacuum relief valve.

Gas Water Heater Controls & Operation

Gas water heater control and thermostat (C) Daniel Friedman

Check that the temperature on your gas control has been set to a safe level.

See Temperature of Hot Water is Too Low and see Anti-Scald Valves & Hot Water Quantity for details about safe hot water temperatures.

Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank

Schematic of a sacrificial anode on a hot water tank (C) Carson Dunlop

The dip tube on many water heaters functions as a sacrificial anode, as we show here. By constructing the dip tube of a metal which is more readily corroded than the steel of a steel hot water tank, the anode protects the hot water tank from early failure due to corrosion. Here Carson Dunlop's sketch shows the location of the sacrificial anode on an electric water heater.

If your water supply happens to be highly conductive or corrosive (see WATER TESTING GUIDE) then the dip tub/sacrificial anode in the water tank may indeed corrode away until it leaks (dropping the hot water temperature) or disappears entirely.

If your hot water smells like rotten eggs, you should definitely check the condition of the sacrificial anode on the hot water heater, no matter what kind of water tank you've got installed.

For details of how to inspect or replace the sacrificial anode or dip-tube on a water heater, please see Water Heater Anodes & Dip Tubes

Check the Gas-fired Hot Water Tank Temperature and Pressure Safety Relief Valve

Please see Testing the Water Heater Temperature Pressure Relief Valves

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GAS FIRED WATER HEATERS
  DRAFT HOODS - gas fired
  Gas BTUH & Cubic Feet
  Gas Conversion LP Natural Gas
  GAS PIPING, VALVES, CONTROLS
  SOOT on OIL FIRED HEATING EQUIPMENT
  SPILL SWITCHES - Flue Gas Detection

GAS PIPING, VALVES, CONTROLS

  • Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
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  • Plumbing Diagnosis & Repair: Water supply, drainage, septic systems, water testing, water contamination, defective plumbing materials & products.
  • Home Reference Book - Carson Dunlop The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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  • Typical Water Tests & Fees this water test fee schedule applies when testing is combined with other onsite building inspection services
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