A boiler issue can creep up slowly or happen without warning. Knowing whether you need a simple boiler repair or a full boiler replacement can save money, reduce stress and keep your home safe.  

In this guide, we’ll run through eight key warning signs to look out for, using plain language to help you understand when it’s time to act. This article covers everything from emergency boiler repair to how long a boiler typically lasts. 

1. Strange or Unusual Smells 

Unusual smells are one of the clearest signs that something is wrong. 
If you notice sulphur, metallic or gas-like odours, you should treat it as urgent. A gas smell may point to a dangerous leak. A burning or metallic smell could indicate overheating components. Don’t wait, turn the boiler off and contact a Gas Safe engineer immediately. 

2. Frequent Boiler Breakdowns 

If you’re calling engineers repeatedly, it’s often cheaper long-term to consider a boiler replacement. Each repair adds cost, and older boilers struggle to maintain performance. Repairs can help for short-term issues, but repeated faults usually indicate declining reliability. 

3. Higher Energy Bills 

A sudden rise in bills can suggest your boiler is working harder than it should. As boilers age, efficiency drops. That means more gas is used to heat the same amount of water. 
If your boiler is 10 to 15 years old, this can be a major sign it’s reaching the end of its lifespan. 

4. Leaks Around the Boiler 

Any visible leak requires fast action. Leaks may come from corroded pipes, broken seals or failing internal components. Water damage can quickly spread to floors or electrics, and leaks are classed as an emergency boiler repair scenario. 
If leaks keep returning, replacing a boiler is usually the safer option. 

5. Radiators Cold but Pipes Are Hot 

If the radiators stay cold but the pipes leading to them are hot, it usually means one thing: circulation issues. This can be caused by: 

• Sludge build-up 

• Faulty pumps 

• Blocked pipes – A flush or repair can fix it, but older boilers may struggle to maintain good circulation. 

6. No Hot Water but Heating Works 

This is often linked to a diverter valve fault, a common repair job. The diverter valve controls whether your boiler sends heat to taps or radiators. When it fails, you might get heating but no hot water. A repair is usually enough unless the boiler is old and other issues are starting to appear. 

7. Frequent Pressure Drops 

If you’re constantly topping up boiler pressure, you may have a leak, a failing expansion vessel or a problem with the pressure relief valve. Some issues can be repaired easily. If pressure drops are combined with age or other faults, boiler replacement becomes a sensible option. 

8. Noises From the Boiler or Radiators 

Boilers shouldn’t make loud noises every day. Common sounds include: 

• Kettling (a boiling kettle noise) 

• Whistling 

• Tapping or clunking – Often this comes from limescale or sludge build-up, which restricts water flow. A repair or clean-out may solve it, but continued noise on an older system can be a sign it’s wearing out. 

Boiler Repairs 

If the boiler is safe and the fault is minor, a repair is usually the best option. Common repairs include: 

• Ignition problems 

• Pump failures 

• Sensor faults 

• Thermostat issues 

• Diverter valve faults 

Emergency boiler repair is needed when there are leaks, no heat during winter, or any smell of gas. In these cases, turn the boiler off and call a professional. 
Always use a Gas Safe registered engineer. 

Boiler Replacement 

There comes a point where repairing a boiler no longer makes sense. You should consider boiler replacement if: 

• Repairs are becoming frequent or expensive 

• The boiler is over 15 years old 

• It struggles to heat the home consistently 

• You are seeing leaks or safety concerns 

A new boiler installation offers improved efficiency, lower bills, quieter operation and a new warranty. Many homeowners search for terms like when should you replace a boiler or how often should you change your boiler – and the answer often depends on age, reliability and repair history. 

Boiler Servicing 

Regular boiler servicing helps avoid sudden breakdowns. A yearly service keeps the boiler safe, checks for potential faults and helps maintain efficiency. 

During a boiler service, the engineer typically checks combustion levels, cleans internal parts, tests safety controls and ensures everything is running correctly. 

A serviced boiler usually lasts longer and stays within warranty terms. 

FAQs 

• How long does a boiler last?

  Most boilers last between 10 and 15 years. Lifespan depends on build quality, usage and whether it’s been serviced regularly.

• When should you replace a boiler?

  You should consider a replacement when repairs become frequent, efficiency drops, or the boiler is over 15 years old.

• How often should you change your boiler?

  Many households choose to replace boilers at around the 12–15 year mark to avoid breakdowns and higher bills.

• Is it better to repair or replace an old boiler?

  If the boiler is under 10 years old, a repair is often fine. Older boilers with repeated faults usually cost more long-term than a replacement.

• Why does my boiler keep losing pressure?

  Common causes include leaks, a faulty expansion vessel or issues with the pressure relief valve.

• How long does a new boiler installation take?

  Most installations take between one and two days, depending on the type of boiler and pipework.

Boiler Replacement & Repairs Swindon  

Recognising early warning signs can prevent bigger problems later. Whether you need a quick boiler repair, an emergency callout or a full boiler replacement, Myza Gas can help you. 

Myza Gas provides boiler installation, servicing and repairs, including 24/7 emergency support. Call our friendly team today on 01793 251 552.