Hot water system not working? The quick checks before you call a plumber

If your hot water system stopped working this morning, the good news is that most failures are fixable without a plumber for at least the first half-hour. Here are the five things to check before you make a phone call, and the symptoms that tell you to skip the checks and call straight away.

These checks apply to most Sydney residential hot water systems, whether gas storage, gas continuous flow (instant), electric storage, or solar with electric boost. Each has its own failure pattern, so identifying which type you have is the first step. The label on the side of the unit, or the brand and model, narrows it down quickly.

Five things to check first

• The power or gas supply to the unit. Electric storage: check the unit's circuit breaker at the switchboard. It may have tripped overnight. Gas: check the gas isolation tap at the unit is on, and that other gas appliances in the house (hob, oven) are working. If they aren't, the supply itself is off.
• The pilot light, if you have a gas storage system with a pilot. A pilot can blow out from a sudden draft or a thermocouple aging out. Manufacturer instructions inside the access panel show how to relight. If it relights and stays lit, you're back in business. If it relights and goes out within a minute, the thermocouple needs replacing and that's a plumber job.
• The temperature setting on the thermostat. Storage systems have an external dial or thermostat. If it was knocked down to the lowest setting (sometimes accidentally during cleaning), the water in the tank can drop below useable temperature. Turn it back up to around 60°C, which is the minimum Australian plumbing standards require to prevent Legionella growth in storage tanks, and check again later.
• The cold water supply to the unit. If the cold water inlet is closed, no water enters the tank and the hot taps run cold or empty. The inlet valve is usually on the cold-water pipe directly above the unit.
• The pressure relief valve (PRV) for signs it's been venting heavily. PRVs that have been discharging large amounts of water indicate either high tank pressure (often a failed expansion valve) or a degraded valve seat. A small drip is normal. A continuous stream is not.

Signs to skip the checks and call straight away

• Visible water leaking from the unit or pooling underneath it. A storage tank that's started leaking from the tank itself rather than a fitting is at end-of-life and can't be repaired.
• A strong gas smell near the unit. Treat as a gas leak first, call Jemena on 131 909 before doing anything else, and get a gas fitter to inspect once the supply is isolated.
• The PRV is discharging continuously, not dripping.
• The unit makes a loud rumbling, popping, or banging sound during heating. Usually scale build-up on the heating element or in the tank. Worth replacing rather than repairing once it's noisy.
• The unit is more than 12 to 15 years old and has just stopped working. The economic decision is usually replacement, not repair.

When you do call a plumber, what to mention

From Norton Plumbing's experience, the diagnostic information you provide on the phone often determines how quickly the visit gets resolved. When you call, have the following ready:

• Brand, model, and approximate age of the unit. The data plate is on the side.
• Whether it's gas, electric, or solar with boost, and storage or continuous flow.
• What you've already checked from the list above, so the plumber doesn't repeat your checks.
• Whether anyone has touched the unit recently. A new installation, a service visit, or plumbing work elsewhere in the house can all be related causes.

How to reach Norton Plumbing

Norton Plumbing handles hot water system callouts across Sydney's Eastern Suburbs. We operate from 10/11a-15 Berwick Street, Coogee NSW 2034. Phone: 0477 858 951. Adam Norton holds NSW plumbing licence 397768C and a gas fitter's licence. We work across Eastern Suburbs including Bondi, Coogee, Randwick, Maroubra, and Kingsford. During business hours there is no callout fee. For more detail on the systems we work on, the hot water service page covers gas, electric, solar, and heat-pump options.