Water Heater Basics
The first step in understanding how to maintain and troubleshoot a water heater is to understand what makes them work. Not every leak or cold water call means replacing the unit—but some do, and here’s how to tell the difference.
Water heaters are fairly simple machines. Tanks hold water that is heated by electric or gas energy. That water temperature is monitored by a thermostat, and the hot water is piped out of the tank when faucets are opened down the line. So, when water is not hot enough—or not staying hot long enough—there are only a few potential causes. And, when water heater parts go bad, they are generally easy to replace.
That’s not to say water heater repair is always fast. Draining and properly refilling a water heater can be time consuming, but taking the time to do it right will protect the equipment, as well as the unit, and save trouble in the future.
Looking Inside Water Heaters
Electric and gas water heaters share many parts, but there are some that are unique to each.
Electric Only
- Electrical Supply Line
- Upper Element
- Lower Element
- Upper Thermostat
- Lower Thermostat
Shared Parts
- Cold Water Pipe/Valve
- Hot Water Outlet
- Temperature Pressure Relief (T&P) Valve
- Overflow Pipe
- Anticorrosion Anode
- Dip Tube
- Insulation
- Drain Valve
Gas Only
- On/Off Pilot
- Temperature Control
- Burner
- Thermocouple
- Air Shutter
- Shutoff Valve
- Flue pipe
- Draft Diverter
- Gas Supply
Is the Water Heater Leaking?
A leaking water heater may or may not be a big problem. When gallons of hot water are under pressure, a leak can lead to serious damage. There is good news—not all leaks mean the water heater is about to go. Water heater leaks can come from the tank itself or from one or more of the pipes and fittings that move the water from the tank through the residence.
Water on the floor or in the area surrounding the tank doesn’t necessarily mean the tank itself is leaking, it could be the drain valve, temperature and pressure relief valve, the water lines that run in and out of the tank, and even condensation. If there is visible rust on the tank or water leaking from a pinhole in the tank body, the water heater will need to be replaced.
Signs of a leak? Check for tank condensation, then investigate these possible causes: Visible rust or holes in the tank, faulty drain valve, T&P valve, water lines, and connections.
Is the Water Heater Not Heating?
If there is no leak, and the water heater issue on the service request lists “no hot water” or “not enough hot water,” there are a few things to check. The checks for electric and gas water heaters are similar, but there are some key differences.
Follow these water heater troubleshooting workflows and download the easy-to-follow to find out why the resident is not getting enough hot water.
