Boiler Maintenance Basics: 4 Things to Check Each Year

TL;DR: A few simple boiler checks keep your heat reliable and your home safe — and tell you what you can handle vs. what needs a pro.

_Last reviewed: July 2026 · 2 min read_

A boiler is the heart of a hydronic heating system, and a little yearly attention keeps it reliable, efficient, and safe. Four basics cover the homeowner side — and make clear where a professional takes over.

A safety note: boilers burn fuel and produce carbon monoxide if something's wrong. Annual servicing and a working CO detector are not optional. Leave burner, gas, and combustion work to a qualified heating engineer.

What pressure should a boiler be at?

Check the pressure gauge is in the normal range — typically around 1 to 1.5 bar when cold for most domestic boilers (check your unit). Too low and the system won't circulate properly; too high can trip the relief valve. If pressure is low, many boilers have a filling loop to top it up per the manual. Pressure dropping repeatedly suggests a leak worth investigating.

Should I bleed radiators before calling about the boiler?

Yes — bleed the radiators before assuming the boiler is at fault. If rooms aren't heating evenly, trapped air in the radiators (cold tops, warm bottoms) is often the culprit, not the boiler — and bleeding them is a free DIY fix. Rule that out first; you may save a service call.

How often should a boiler be serviced?

Schedule a professional service once a year, ideally before heating season. A qualified engineer checks combustion, the heat exchanger, seals, controls, and safety devices — things you should never DIY. Annual service keeps the boiler efficient, catches problems early, maintains the warranty, and (most importantly) confirms it's burning safely.

Why test the carbon monoxide detector near a boiler?

Because a faulty boiler can leak carbon monoxide — colorless, odorless, and deadly. Test a CO detector near the boiler (and have one on each level), and make sure it's working and not expired. This is the single most important safety step around any combustion appliance — see our detector schedule. If a CO alarm sounds, leave and call for help.

Track boiler service

Logging your annual service date and pressure checks keeps heat reliable and safe. Okoniq Property Hub keeps it with your home maintenance records in one private place.

Frequently asked questions

Why does my boiler keep losing pressure?

A small leak somewhere in the system, a faulty pressure relief valve, or a failing expansion vessel are common causes. Top it up per the manual; if it keeps dropping, have an engineer find the leak.

What boiler problems should I never DIY?

Anything involving the burner, gas supply, combustion, the heat exchanger, or internal components. Those are for a qualified/licensed heating engineer — DIY there is dangerous.

Okoniq Property Hub helps homeowners and landlords keep maintenance, bills, and contractor info in one calm place. Get started free.

FAQ

How much does an annual boiler service cost in the US?

Annual boiler service typically runs $150 to $300, depending on your region and the type of boiler. Expect higher costs if the technician finds parts that need replacement during the inspection.

Can I service my own boiler to save money?

No — combustion appliances require a qualified or licensed heating engineer for safety and warranty reasons. Homeowners should only check pressure, bleed radiators, and test CO detectors; everything else is a professional job.

What are the warning signs a boiler needs immediate repair?

Strange noises (banging, whistling), yellow or orange flame instead of blue, soot around the unit, or the carbon monoxide detector alarming all require shutting down the boiler and calling an engineer immediately.

How long does a typical boiler last before it needs replacing?

Most residential boilers last 15 to 20 years with annual service. If yours is approaching that age and needing frequent repairs, replacement is often more cost-effective than continuing to fix an old unit.