This 3-page article from the ICC lists 13 common problems that inspectors can expect to encounter with water heaters. Illustrations and explanations are clear.
- Response to the demand for hot water
- Describe as gas, electric, or tankless (if gas WH is tankless, recommend service);
- General exterior condition;
- Seismic straps where necessary;
- Recommend anode rod replacement? (deterioration rate depends on water composition).
- Gas water heater should be located minimum 10 ft. from return air vent
- Not allowed in bathrooms or storage closets (especially bedroom closets).
- If in garage, must be on 18-inch minimum height platform, unless FVIR (Confirm with local codes).
- Serial number
- Tank capacity
- Year of manufacture (comment if past warranty)
- Cold water shut-off installed within arm's length
- Gas shut off installed
- Flex gas pipe max. 36" with gas shut-off valve;
- Sediment trap (makes gas flow change direction) installed;
- Check fittings for gas leaks
- Combustible gas detector
- Soapy water solution
- Your nose
Temperature/Pressure relief (TPR) valve and discharge;
Discharge pipe defects:
- None installed;
- Terminates more than 6 inches above floor;
- Termination capped;
- Termination threaded;
- Termination not visible;
- Terminates in drip pan;
- Terminates outside;
- Terminates in crawlspace;
- Restricted termination;
- Smaller diameter than TPR valve outlet;
- Connected to waste pipe;
- In-line pump installed;
- Trap installed
- Improper pipe material; or
- 1 discharge serves multiple TPR valves.
Combustion Air Requirements:
There is no one simple formula for calculating adequate combustion air. Calculations must be adjusted for homesite conditions. Unless you're sure about conditions, I suggest you describe the presence of any combustion air supply ducts, say- at the most- that it appears to be enough or insufficient, and disclaim if there's any doubt.
Combustion appliances require 50 cubic feet per 1000 BTU per hour (BTU/h) aggregate input. "Aggregate" means that if two combustion appliances such as a gas-fired furnace and a gas-fired water heater are installed in the same room, each of their input ratings in BTU/h must be included when calculating adequate combustion air.
- Flammable Vapor Ignition Resistant (FVIR) type water heaters required since 2003.
- Blue flame desirable, red or yellow flame recommend service
- Rust flakes on chamber floor indicate tank deterioration
- Proper chamber cover
- Soot/carbon on exterior above chamber?
Combustion Exhaust Venting
- Proper draft diverter
- B vent
- 1-inch clearance to combustibles
- Adequate slope (1/4-inch per foot)
- Joins shared vent stack above furnace or boiler vent
- Vents into unsealed brick chimney? (defect)
- Backdrafting? With other combustion appliances operating?
- Corrosion/white powder indicated moisture problems (possible inadequate draft)
Signs of Backdrafting:
- Melting or distortion of plastic escutcheons where hot and cold pipes penetrate the top of the water heater.
- Corrosion on top of tank (white or rust-colored).
- Moisture on top of the tank.
- Heavy condensation on the cold-water pipes in the room.
- Improper slope or excessively sharp turns of the combustion exhaust vent.
Testing for backdrafting:
- Turn down the thermostat if the furnace or boiler shares the exhaust vent;
- Close all doors and windows;
- Close any open fireplace dampers;
- Turn on all kitchen, bathroom and laundry room exhaust fans;
- Turn on the clothes dryer;
- Run the hot water long enough to activate the water heater burner;
- Backdrafting will fog a camera lens & you can feel it on your hand.
- Corrosion on fittings;
- Make sure connects are not reversed;
- Cold water shut-off within arm’s length;
- Electrical bonding and jumper between hot and cold pipes;
- Combustible material clearance from exhaust flue;
- Cold water supply pipe soldered directly to cold water inlet may damage dip tube or tank.
Check your jurisdiction, may be required on newer systems.
Hot Water Re-circulation System
Comment if installed and whether it's working (short wait for hot water at fixture furthest from water heater).