Losing hot water is rarely dangerous, but it throws a household off fast, and a fair number of calls turn out to be something you could have checked in a few minutes. Others shouldn't be touched at all. This guide sorts one from the other for the three kinds of water heater most common in Lower Mainland homes: electric tanks, gas tanks and tankless units.
Safety first
- If you smell gas (a rotten-egg smell), don't troubleshoot anything. Leave the house, don't use light switches or anything that could spark, and call FortisBC's 24-hour emergency line from outside. The number is on their website and on your gas bill.
- If the tank is leaking, close the cold water valve on the pipe feeding it, then turn the heater off: switch off the breaker for an electric tank, or turn the control on a gas tank to its off setting.
- If water is pooling near outlets or the electrical panel, keep clear and get help.
If you aren't sure where your shut-off valves are, our guide to finding your water shut-off is worth reading before you need it.
Is it every tap, or just one?
This one question splits the problem in two.
If the kitchen has hot water but the shower doesn't, the heater is fine. The fault is at the fixture, most often the cartridge or mixing valve inside the shower valve. It blends hot and cold, and when it fails or clogs it can let only cold through. That is a fixture repair, not a water heater problem.
If no tap in the house has hot water, or every tap has gone lukewarm, look at the heater.
Electric tank: what to check
- Check the breaker. If it has tripped, reset it once. If it trips again, stop: something in the heater is drawing too much current and needs repair.
- Many electric tanks have a high-limit reset button behind the upper access panel. Pressing it can bring the heat back, but the panel covers live wiring, so switch the breaker off before you remove it. If the reset trips again later, a thermostat or element has failed.
- No hot water at all usually points to the upper element or its thermostat. A little hot water that runs out quickly usually points to the lower element.
Testing and replacing elements and thermostats means working around live electrical parts. If the simple checks don't sort it out, that is the point to call.
Gas tank: what you can look at, and where to stop
On a gas tank, check that the control knob hasn't been turned to its vacation or pilot setting, which happens more often than you would think when a tank gets bumped or someone has been working in the room. If your model has a viewing window, you may be able to see whether the pilot or burner is lit.
If the pilot is out, the label on the tank has the manufacturer's lighting instructions. If it won't light, or won't stay lit, don't keep trying. The burner, pilot assembly, gas valve and venting are the gas side of the heater, and that is work for a licensed gas contractor. The water side, meaning the connections, the relief valve, leaks and the tank itself, is where a plumber comes in.
Tankless: read the display first
- Most units show an error code when they shut down. The owner's manual explains each code, and many have simple causes, such as a closed valve or a blocked air intake.
- A tankless unit needs a minimum flow of water before it fires. A single low-flow tap opened only a little may not be enough to switch it on.
- Units need regular flushing to clear mineral buildup. One that has never been maintained can start shutting down or delivering lukewarm water.
- Check that the unit has power. A tripped breaker or GFCI stops it as completely as any fault.
If you are weighing a replacement, our guide to tankless installs in BC covers what the job involves.
The relief valve: never cap it
Every tank has a temperature and pressure relief valve, usually on the top or upper side, with a pipe running down toward the floor. It opens if the pressure or temperature inside the tank gets too high. A valve that drips now and then can point to high water pressure in the house, thermal expansion, or a valve that is wearing out, and all of those are worth having checked. What you should never do is plug or cap the valve or its pipe to stop the drip. It is the safety device that keeps the tank from rupturing.
Signs the tank itself is finished
- Water leaking from the body of the tank rather than from a fitting or valve
- Rusty or discoloured water from the hot side only
- Rumbling or popping as the tank heats, caused by sediment on the bottom
- Hot water running out much sooner than it used to, even after repairs
A leak from the tank body can't be repaired. Rust and sediment noise don't mean failure is days away, but they do mean it is time to plan a replacement rather than wait for one.
Our water heater buying guide compares the options for Lower Mainland homes, and our water heater repair page covers repairs and replacements.
Dealing with this right now? Mr. Plunger Plumbing & Drainage answers 24/7 across Surrey, Delta, Langley, White Rock, Richmond, Maple Ridge, Pitt Meadows, Vancouver and the rest of the Lower Mainland. Call (604) 870-1442 to talk to a real plumber, get an ETA before anyone is dispatched, and get a quote before any work starts.