Service, maintenance and troubleshooting

By the time the last floors of Kingsway Tower were finished, the first tenants had already moved into the lower floors, and the service calls had started: a toilet that ran all night, a shower that went cold when someone flushed next door, a kitchen faucet that dripped, and one suite where the hot water smelled like rotten eggs. Luis sent Maya out on these calls with a service truck and a rule. "Don't start by replacing parts," he said. "Start by asking questions and looking. Most problems tell you what they are if you let them."

This final lesson brings the course together. It covers routine maintenance of fixtures and water heaters, a method for troubleshooting, the most common problems and their causes, and the turnover and service records that close out a project. It ends with a capstone in which Maya works through a set of Kingsway service calls.

A method for troubleshooting

Good troubleshooting follows the same steps whatever the problem. First, gather information: ask the occupant what happens, when it started, whether it is constant or intermittent, and whether anything changed, such as a renovation, a new appliance or a water shutdown. Second, observe: see the problem yourself, look, listen and measure. Third, think about the system: which parts could cause this symptom, and in what order are they most likely? Fourth, test: check the most likely and easiest causes first, one at a time. Fifth, repair the cause, not just the symptom. Sixth, verify: confirm that the problem is gone and nothing else was disturbed. Finally, record what was found and done.

Two habits make the method work. One is changing one thing at a time, so that you know which change fixed the problem. The other is thinking about the whole system, not just the fixture in front of you. A relief valve that drips might be a bad valve, but it is more often a sign of high pressure or thermal expansion elsewhere in the system. A shower that runs cold when a toilet flushes is a pressure-balancing problem at the valve, but it might also point to an undersized branch.

Common fixture problems

Most fixture service calls fall into a handful of familiar problems. The table below lists them with their usual causes. Experienced plumbers carry the common repair parts for the fixtures in the buildings they service, so that most calls end with one visit.

The last row is worth remembering because it confuses people. Crossflow happens when hot and cold water can connect through a fixture or valve, for example a single-handle faucet or a mixing valve whose internal check valves have failed. When the pressure on one side is higher, water flows from that side into the other piping. The symptom may show up far away, as warm water at a cold tap in another room, or a mixing valve that cannot hold its temperature. Finding it means checking each likely fixture, often by shutting off the hot supply to one fixture at a time and seeing whether the symptom stops.

Shower valves are a particular case. A pressure-balancing cartridge that sticks with mineral deposits may let the temperature swing when another fixture is used, or may lock in a position that gives only cold water. Replacing the cartridge with the manufacturer's part is usually the fix, and after any cartridge replacement, the high-limit stop must be checked and reset with a thermometer, exactly as at installation. A cartridge replacement that resets the stop to the factory position can leave a valve able to scald.

Water heater maintenance

A storage water heater lasts longer and works better with simple periodic maintenance. Manufacturers' recommendations vary, but a typical annual service includes these tasks.

• Test the relief valve by lifting the lever briefly, standing clear of the discharge, and check that it reseats without dripping; replace it if it leaks.
• Flush sediment from the tank through the drain valve until the water runs clear, which keeps the burner or lower element from overheating under a layer of scale.
• Check the anode rod every few years, and replace it when it is worn down to its core wire.
• Check the expansion tank's air pre-charge with the tank isolated, and replace the tank if water comes out of the air valve.
• Check the temperature at a nearby fixture and at the heater, and confirm mixing valves are holding their settings.
• Check for leaks at connections, the drain pan and its drain, and look for corrosion.
• For gas heaters, have the gas fitter check the burner, flame, venting and combustion air; for tankless heaters, descale on schedule; for heat pump water heaters, clean the air filter and check the condensate drain.

On the Kingsway central plant, these tasks were part of the operations and maintenance manual that Northbridge handed over, with a schedule, the manufacturer's instructions and the settings recorded at start-up. A good maintenance schedule turns surprises into routine work.

Common water heater problems

No hot water from a gas heater usually means the burner is not firing: a pilot or igniter problem, a failed flame sensor or thermocouple, a gas supply problem, or a tripped high limit. Those repairs belong to a licensed gas fitter, as Lesson 10 explained, but the plumber can check simple things first, such as whether the gas valve is on and whether the heater has power if it needs it.

No hot water from an electric heater usually means a tripped breaker, a tripped manual-reset high limit, a failed element or a failed thermostat. Testing elements and thermostats means working on live electrical parts only after the power is locked out, and in many places this work is limited to people with the right training or licence. An element can be checked with a meter after the power is off: its resistance should match the value calculated from its rating, roughly 13 ohms for a 4500 W element at 240 V. An open circuit means a burned-out element.

Not enough hot water can mean a heater that is too small for the demand, a failed lower element on an electric heater, a broken dip tube letting cold water mix at the top of the tank, a thermostat set too low, a heavy layer of sediment, or a crossflow somewhere in the system diluting the hot water. A heater that gives hot water for a short time and then runs cold, with an electric heater, often has a failed lower element: the upper element heats the top of the tank, then hands over to a lower element that does not work.

Hot water that smells like rotten eggs is caused by bacteria in the tank that reduce sulphates in the water to hydrogen sulphide gas, often helped by the magnesium anode. The usual cures are to disinfect the tank and replace the magnesium anode with an aluminum-zinc or powered anode, as the manufacturer allows. Noisy heaters that rumble or pop usually have sediment on the bottom, where water trapped under the scale boils; flushing helps, and a heavily scaled tank may need replacing.

A dripping relief valve is a signal, not just a nuisance. It may be a worn valve, but it is often caused by high pressure from the supply or thermal expansion in a closed system. Measuring the static pressure with a gauge on a hose bibb or the drain valve, and watching it while the heater fires, shows which: a pressure that climbs as the heater runs points to thermal expansion and a missing or failed expansion tank.

# Check an electric water heater element with a meter reading (power locked out!)
def expected_ohms(watts, volts):
    return volts ** 2 / watts

rating_w, volts = 4500, 240
exp = expected_ohms(rating_w, volts)
for name, reading in (("upper element", 12.9), ("lower element", None)):
    if reading is None:
        print(f"{name}: open circuit -> element burned out, replace")
    elif abs(reading - exp) / exp < 0.10:
        print(f"{name}: {reading} ohms, expected about {exp:.1f} -> good")
    else:
        print(f"{name}: {reading} ohms, expected about {exp:.1f} -> suspect")

upper element: 12.9 ohms, expected about 12.8 -> good
lower element: open circuit -> element burned out, replace

This matches the classic pattern of a heater that gives a short burst of hot water and then runs cold: the upper element is good and heats the top of the tank, and the lower element is open. Replacing the lower element, after draining the tank below it and with the power locked out, restores full capacity. Before turning the power back on, the tank must be full and the air bled out, as Lesson 7 stressed.

Turnover and records

When a project like Kingsway Tower is finished, the plumbing contractor hands it over to the owner with a package of records. PLB-130 described the water system records; for fixtures and water heaters, the package includes the fixture schedule as built, the manufacturers' installation and maintenance instructions, warranty registrations, the recorded settings of every shower valve stop and mixing valve, the start-up sheets for each water heater signed by the plumber and the gas fitter, the expansion tank pre-charges, and a maintenance schedule. Training the building's maintenance staff on the equipment is often part of the contract.

These records are not paperwork for its own sake. When a tenant reports scalding water two years later, the record shows what the stop was set to and who set it. When a water heater fails under warranty, the start-up sheet and the maintenance log decide whether the warranty is honoured. And when a new plumber comes to service the building, the records tell them how it was built.

Capstone: a week of Kingsway service calls

In her last week on the Kingsway job, Maya handled the first round of tenant service calls on her own, with Luis reviewing her reports. Each call used the method from the start of this lesson.

• Suite 304, toilet runs at night: she watched the tank refill every few minutes, found the flapper warped and the fill valve set too high, replaced the flapper, lowered the water level to the mark and confirmed the tank held overnight.
• Suite 512, shower goes cold when the toilet next door flushes: she found the pressure-balancing cartridge stiff with scale, replaced it, then reset and recorded the high-limit stop at the code maximum.
• Suite 208, warm water at the kitchen cold tap: she shut off the hot stop at the bathroom lavatory and the warm water stopped; the lavatory's single-handle faucet had a failed internal check, which she replaced.
• Suite 701, rotten egg smell from the hot water: the suite was fed by the central plant, so the smell pointed to a dead leg in the suite piping with stagnant water; flushing the line cleared it, and she reported the dead leg to the engineer.
• Café, relief valve dripping on the electric heater: a gauge showed the pressure climbing as the heater fired, the expansion tank was full of water, and she replaced the tank and set the new one's pre-charge to the supply pressure.

Luis read the reports and handed them back with one comment: they were the kind he would want to find in a building file if he were the next plumber in. That, he said, was the real end of the job.