Guide to Electric Hot Water Heaters - Inspection, Diagnosis, & Repair
InspectAPedia^®  -    

• Electric Water heaters: how to inspect, test, adjust, repair a water heater
• How to find & identify the parts & controls on an electric water heater
• How to test and repair an electric hot water heater
• Test procedure for electric water heater high limit cutoff thermostat switch
• Test procedures for electric water heater heating elements
• How to replace the heating element on an electric water heater
• Guide to inspection of electric water heaters
• No Hot water? how to get more hot water flow, quantity, performance from your water heater

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

if you can find your water heater tank at all, take a look at what pipes and wires are connected to it. If you do not see any connection to a chimney, and if you do not see any oil or gas burner, your hot water tank is going to be one of these:

• An electric water heater: you'll find an electric wire entering the heater, usually at the top, and connected to a fuse or circuit breaker in your main electrical panel. Usually the circuit supplying power to the electric water heater will be 40A or larger. There will usually be just two water pipes connected to this device: cold-water in and hot-water out.
• An indirect-fired water heater: you'll find a circulator pump and four pipes connected to this water tank. See  Indirect-fired Water Heaters for photos and details.
• A range boiler: you'll find four pipes connected to this water tank, no electrical wires. See Range Boiler Water Heaters for details and photographs of range boilers.
• A solar water heater tank: you'll see lots of pipes and wires connected to this tank, a circulator, controls, and more stuff. See Solar Water Heaters for photos and details about solar hot water heating.

Drains: Water heater drain valve leaks: Check for leaks at the water heater drain valve. Most water heater manufacturers recommend that their water tank be drained periodically.

This process will help remove sludge and debris or mineral deposits that may have accumulated at the bottom of the water heater tank. Removing this debris can extend the life of the hot water tank, especially where electric and gas fired water heaters are involved. But since few people remember to open and drain the tank it may be that the drain valve does not open easily, or worse, it won't close. For details also see How to Drain a Hot Water Heater Tank

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

Leaks: Water heater leaks: 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 above left an oil-fired water heater and an indirect-fired water heater are installed in tandem. That puddle on the floor needs investigation.

Mobile Homes: Water heater in mobile home: common defects - see MOBILE HOME WATER HEATER DEFECTS

Pipes & Valves: Water heater piping & valves: check the 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.

Noises: Water heater clanking noises: check the electric hot water tank for lime, mineral, or silt deposits and build-up on the tank bottom and on the heating electrodes. Water heater hissing noises: on an electric water heater a hissing sound may be noticed when the heater is operating. This sound may be due to mineral scale or lime build-up on the heating electrodes. Remove, inspect, and clean the electrodes when this sound is observed. See Water Heater Noises for details.

Relief Valve: Water heater temperature/pressure relief valve: 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. For details about water heater relief valves, please see Testing the Water Heater Temperature Pressure Relief Valve, and also see Relief Valves - TP Valves for heating equipment in general

Scale: Water heater scale, clanking noises, or reduced hot water quantity or temperature: see Water Heater Noises for details about removing scale from a water heater. Water heater scale forming on electric water heater elements can cause water heater element failure, water heater noises, or reduced water heater output.

Temperature: Water heater temperature settings: Check the settings of the water heater temperature: See Temperature of Hot Water is Too Low. On an electric water heater, temperature settings are usually made on a control hidden behind the upper and/or lower removable access panel covers that give access to the upper and lower heating element.

Contact Daniel Friedman for website content suggestions or for fee-paid consulting