How Often Does a Boiler Need to Be Serviced?

Boilers keep homes warm in winter, but most people forget about them until they stop working. If you live in a place like Auckland, where winters can turn chilly and damp, your boiler isn’t just a convenience-it’s essential. But how often should you actually get it checked? The short answer: once a year. That’s the standard recommendation from heating professionals, manufacturers, and safety regulators across New Zealand and beyond.

Why Annual Servicing Isn’t Optional

A boiler is a pressurized system that burns fuel to heat water. That means it’s got gas lines, valves, heat exchangers, and electrical components all working together under high temperatures. Over time, dust builds up. Parts wear down. Small leaks develop. These aren’t always obvious until something breaks-or worse, becomes dangerous.

Every year, WorkSafe New Zealand reports cases of carbon monoxide poisoning linked to poorly maintained heating systems. Carbon monoxide is silent, odorless, and deadly. A well-serviced boiler has safety checks built in to prevent this. A neglected one? It’s a ticking time bomb.

Manufacturers also require annual servicing to keep warranties valid. If your boiler is only two years old and you’ve never had it checked, you might be surprised to learn your warranty is already void. That’s not a trick-it’s standard practice. Service records prove you’ve taken care of the system.

What Happens During a Boiler Service?

A professional boiler service isn’t just a quick glance. It’s a full diagnostic. Here’s what you should expect:

• Checking gas pressure and flow rates
• Inspecting the heat exchanger for cracks or corrosion
• Cleaning the burner and flue system
• Testing safety controls like thermostats and pressure valves
• Checking for carbon monoxide leaks with a detector
• Verifying the condensate pipe isn’t blocked
• Examining electrical connections and wiring
• Providing a service certificate with findings

Most services take between 45 and 75 minutes. A good technician will explain what they found, show you any wear and tear, and tell you if something needs replacing soon. They won’t just push upgrades-they’ll give you honest advice.

What If You Skip It?

Skipping a service might seem harmless. Maybe your boiler is still heating the house. Maybe you haven’t noticed any strange noises. But problems don’t announce themselves. They creep in.

Here’s what happens over time:

• Efficiency drops - Dust and scale build up inside the heat exchanger, forcing the boiler to work harder. That means higher gas bills. One study by Energywise found that poorly maintained boilers can use up to 15% more fuel than well-serviced ones.
• Breakdowns increase - A boiler that’s never been serviced is three times more likely to fail during winter. That’s not a guess-it’s based on repair data from New Zealand heating companies.
• Repair costs climb - A simple part replacement, like a faulty pump or pressure sensor, might cost $150. But if you wait too long, that small issue can destroy the heat exchanger. Replacing that? $1,200 to $2,500.
• Safety risks grow - Cracks in the heat exchanger can leak carbon monoxide into your home. No alarms, no smells, just slow poisoning. In 2024, New Zealand had 17 reported cases of carbon monoxide poisoning from faulty heating systems. All were linked to neglected boilers.

When Should You Schedule Your Service?

There’s no perfect month, but timing matters. Most people wait until winter hits and then panic when the boiler fails. Don’t do that.

Best time? Early autumn. In New Zealand, that’s March to May. Why?

• Heating companies aren’t swamped yet-you’ll get faster service.
• Technicians have time to order parts if needed.
• You avoid the rush before winter, when prices often go up.
• You’ll know your boiler is ready before the cold snap hits.

If you’ve never had a service, don’t wait for next autumn. Book it now. Even if it’s February, it’s better late than never.

Are There Exceptions?

Some people think, “My boiler is new,” or “It’s a combi model,” or “I use it rarely.” None of that changes the rule. Even if you only turn the boiler on once a week, it still needs annual servicing.

There’s one exception: if you’ve installed a modern, sealed-system boiler with a self-diagnostic feature. Some newer models (like Vaillant EcoTEC or Worcester Bosch Greenstar) can send alerts to your phone if something’s wrong. Even then, a physical inspection is still required. Sensors can’t catch everything-especially gas leaks or internal corrosion.

How to Find a Reliable Technician

Not all boiler technicians are equal. In New Zealand, anyone can claim to be a heating engineer. But only those registered with the Gas Safe Register is the official body in New Zealand that certifies gas fitters and boiler engineers are legally allowed to work on gas appliances.

Always ask for their registration number. You can check it online at the Gas Safe Register website. Look for someone who specializes in boilers-not just general plumbers. Ask if they carry carbon monoxide detectors. If they don’t, walk away.

Read reviews. Ask neighbors. A good technician will explain what they’re doing, show you the old parts, and give you a written report. If they rush through it or refuse to answer questions, find someone else.

What About Boiler Filters and Flushes?

Some companies push annual power flushing-claiming it extends boiler life. It’s not always necessary. A flush is only needed if your system has sludge buildup, which usually shows up as cold spots on radiators or noisy pipes.

Most modern boilers with proper water treatment don’t need a flush every year. In fact, doing it too often can damage seals and gaskets. Ask your technician: “Is there evidence of sludge?” If they say yes, then yes, get it flushed. If not, skip it. Don’t pay for unnecessary services.

What’s the Cost?

In Auckland, a standard boiler service costs between $150 and $250. That includes inspection, cleaning, safety checks, and a certificate. Some companies offer annual service plans for around $180 per year-often with priority booking and discounts on repairs.

Compare quotes. Don’t just pick the cheapest. The cheapest might skip the carbon monoxide test or not clean the burner properly. Look for someone who gives you a detailed checklist and explains everything.

What to Do Between Services

You don’t need to do much between annual checks, but here are a few simple things:

• Check your boiler’s pressure gauge monthly. It should sit between 1 and 1.5 bar. If it’s below 1, you may need to top it up.
• Listen for unusual noises-banging, gurgling, or whistling. These can signal air in the system or a failing pump.
• Keep the area around the boiler clear. No boxes, towels, or storage. It needs airflow.
• Test your carbon monoxide alarm monthly. Replace batteries once a year.

That’s it. No need for DIY repairs. Don’t try to fix leaks yourself. Gas work is dangerous. Leave it to the pros.

Final Thoughts

A boiler isn’t something you fix when it breaks. It’s something you maintain so it doesn’t break. One service a year costs less than one emergency call out in winter. It’s safer. It’s cheaper. It’s smarter.

If you’ve never had your boiler serviced, book it now. If you’re due for one, don’t wait until next year. Get it done before the weather turns. Your family’s safety-and your wallet-will thank you.