A cold shower is a bad start to a day, but a fair share of no-hot-water calls end with the plumber pressing a reset button or relighting a pilot. Ten minutes at the heater can save you the call-out fee, or at least tell the plumber what to bring.
First: which kind of heater?
A gas heater has a gas pipe going into a control box near the bottom, and a vent pipe from the top. An electric heater has no vent, and a cable entering the top or side. A boiler-fed system has no separate heater with its own burner: the hot water comes from the boiler, and the checks are different, see below.
Gas heater
- Is the pilot lit? Look through the small window at the bottom. If it is out, follow the relighting instructions on the label on the tank. On newer heaters this is a button and an igniter; on older ones, a long match or lighter. If it will not stay lit after a couple of tries, the thermocouple or the gas valve has failed, which is a plumber's repair, and a modest one.
- Is the gas on? Check the valve on the gas pipe. The handle should be in line with the pipe. If other gas appliances in the house are also off, call the gas utility.
- Is the control set to hot? Someone may have turned it to Vacation.
- Any smell of gas? Leave the house and call the gas utility or 911 from outside.
- Is the status light blinking a code? Newer heaters flash a pattern that means something. The label decodes it.
Electric heater
- The breaker. Water heaters use a double breaker, usually 30 amps. If it has tripped, reset it once. If it trips again, stop, and call a plumber or an electrician.
- The high-limit reset. Remove the upper access panel on the side of the tank, carefully fold back the insulation, and look for a red button on the thermostat. Press it. If it clicks, it had tripped. If it trips repeatedly, an element or a thermostat has failed.
- Lukewarm rather than cold water usually means one of the two elements has burned out. Replacing an element is a job some homeowners do, with the power off and the tank drained below the element. Many prefer to leave it to a plumber.
Boiler-fed hot water
If your hot water comes from the boiler, check that the boiler is running at all: its power switch, the thermostat, and the pressure gauge. If the heat works but the hot water does not, the problem is usually the zone valve or the aquastat for the hot water side, which is a professional's job.
Some hot water, but not enough
- The thermostat is set too low. 120°F is the usual setting.
- Sediment in the tank has taken up the space the water should be in. Flush it.
- The dip tube inside the tank has broken, so cold water mixes straight into the hot. A plumber can replace it.
- The tank is too small for the household, or someone has changed their habits.
Rusty or smelly hot water
Rusty hot water, from the hot side only, means the tank is corroding inside and the anode rod is used up. If the heater is old, start planning its replacement. A rotten-egg smell in the hot water is a reaction at the anode, common with wells, and a plumber can fit a different type of anode.
When to call a plumber
- A pilot that will not stay lit
- A breaker or reset button that keeps tripping
- Water leaking from the tank
- A relief valve that is dripping
- Any gas smell, after you have left the house
Find a licensed plumber near your town.