When to replace a boiler4 min read

The boiler is one of the most essential appliances in your home and it’s important to know when to replace a boiler. Boilers provide heat and hot water. When it fails to operate there will be no hot showers or central heating. 

A boiler is part of a home’s thermal heating system. It is the letter ‘H’ in ‘HVAC’ which stands for heating, ventilation, and air conditioning. It is a heating device that circulates steam or hot water through pipes and radiators to heat a room. 

A boiler is a vital component of a heating system. It is centrally located in the HVAC model and distributes heat evenly in a household. Boilers can only heat properties that have hot water radiators or steam radiators. Within this article I’ll detail how to maintain a boiler and why this is so important. 

How a Boiler Operates

The way a boiler works depends on the type of boiler you have. The primary function of all boilers is to convert water to heat. Boilers operate by boiling water or releasing steam, which is then used to heat a household.

Although, this is just a rudimentary description of how boilers operate. When you start looking at various types of boilers, the inner workings of a boiler get more complex. Let’s take a closer look at the common operation mechanism shared by all boilers.

  • When your home’s thermostat detects a decrease in temperature, it activates the boiler.
  • When you turn on your boiler, it generates heat using either oil, gas, coal, or electricity.
  • The water inside the boiler is heated by the heat emitted by the fuel supply. 
  • The hot water or steam is distributed around your household (mainly through vents or radiant floor processes) and emits heat to warm the air.
  • When the water cools (or the steam condenses), it returns to your boiler. Water is reheated before being sent back out to finish heating your house.
  • This procedure is repeated until your home hits the desired temperature until your thermostat instructs the boiler to shut down.

Boiler Maintenance Tips and How Long Does a Boiler Last? 

If well maintained, the typical boiler lasts 15 years or longer. While an annual service will extend the lifetime, an older boiler needs to work harder to heat your house. 

Ideally a boiler will operate effectively and reliably for many years. If you don’t get annual services for your boiler, expensive issues can arise. Here are a few boiler maintenance tips to keep your boiler in good working order:

Keep on board with inspections and services

Nothing is more critical for your boiler’s safety and reliability than keeping up with regular inspections and services. Shutting down the boiler for an assessment is inconvenient, but it is worth it if it means verifying that the boiler is operating correctly. 

Keep the interior clean

Thorough maintenance of the boiler’s interior will make a significant difference. Over time, residue forms which limits heat transfer. This causes the boiler to operate inefficiently therefore using more power. The interior should be cleaned with a brush at least once a year. 

Inspect the insulation

Boilers are insulated to prevent heat from escaping. It’s important to inspect the insulation of your boiler for any gaps or damage. 

Check water quality

Monitor the hardness of the water running through your boiler. If your water is particularly hard, this can lead to an excess build up of limescale. This will reduce functionality of your boiler and can damage its components. This will reduce the lifetime of your boiler. If you suspect limescale build up, contact a professional who can install a water filter to prolong the life of your boiler. 

Also consider purchasing a water detector that will automatically test water hardness. 

‘Red Flags’ a boiler needs replacing

Advanced Age

A well maintained boiler can last for 15 years or longer. However, if you haven’t personally owned the boiler since it was new, it’s difficult to know any prior maintenance. It’s important to have a qualified plumber check and advise on whether a boiler needs replacing. 

If your boiler is very old, it may be an ‘open flue’ appliance. This means air is drawn from the room and you’ll have an air vent to maintain the constant supply of oxygen. This old fashioned style of boiler is only 65% – 70% efficient and should be replaced. 

Increased Energy Costs 

Take note of the next monthly electricity bill and monitor the energy costs associated with your boiler. A faulty or unreliable boiler will increase energy costs. It’s also likely that more and more governments impose strict new rules on how efficient your boiler needs to be. Check out this article on the UK government regulating the replacement of old gas boilers. 


Be on the lookout for any signs of leakage. Water leaking from the system may be caused by corrosion damage or a defective component. If leaks are not fixed immediately, the boiler can sustain further damage. Water leaks can also lead to mold, mildew, and further issues in your house.

Hissing Noises

Long-term hissing sounds are usually an indication that silicate minerals have formed within the boiler. These deposits can heat up and deteriorate components. 

Sooner or later, the overall system would shut down. Boiler service technicians will use various assessment tools and products to remove the contaminants. Often the boiler will need replacing if the deposition is severe.

Leaking Carbon Monoxide

Carbon Monoxide is produced by boilers when fuel is not burned completely due to a lack of oxygen. A boiler functions correctly when carbon monoxide releases outside the home via a flue. However it’s possible for this gas to escape into the home.

Carbon Monoxide is a silent killer as it is undetectable by humans. It’s therefore strongly recommended to get a Carbon Monoxide alarm and to regularly replace the batteries.  

What are the Dangers and consequences of not replacing a boiler when necessary?

Home Boilers are the cornerstone of your household heating system.If their productivity reduces they should be maintained and replaced. We’ve narrowed down the three most compelling dangers of not replacing boilers when necessary: 

Significant energy cost spikes

With oil and gas prices increasing this consideration will become more significant. Running an inefficient boiler model will significantly increase fuel cost in the future. Improving your boiler’s operating performance can result in fuel savings of 25% or more. 

Reliability and safety

Modern boilers require less maintenance and are less likely to break. This gives you and your family comfort that your boiler will last the winter.  

While it is impossible to place a price on peace of mind, the inefficiency of old boilers will certainly cost more in the long run. 

Final Thoughts

If there are red flags your boiler needs replacing and you’re spending more and more on maintenance, don’t ignore the issue. You’ll end up spending more in the long run. 

There are also grants available to help with the cost of boiler and heating control upgrades. This could offset the initial financial burden of replacing the boiler and you could see cost savings sooner than you thought. The quicker you replace the boiler with a more efficient one, the sooner you can start saving.

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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

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