7 Common Mistakes to Avoid When Buying a New Boiler
Imagine spending thousands on a new boiler, only to realize it’s too small for your home. The radiators barely get warm, and your energy bills keep climbing as the system struggles to keep up.
Unfortunately, we’ve seen this happen too many times.
Buying a new boiler is a major decision—one that impacts your home’s comfort, energy efficiency, and long-term costs. Get it wrong, and you could be stuck with endless repairs, high running costs, or a system that simply doesn’t meet your needs.
At Rowlen, we’ve guided countless homeowners through this process to ensure they get the right system, not just any system.
Don’t make an expensive mistake—watch out for these 7 common mistakes to avoid when buying a new boiler.
With Rowlen Boiler Services, you get to enjoy the benefits of a well-informed decision. Contact our experts today and skip the hassle of buying the wrong boiler for your home. Find us here.
1. Choosing the Wrong Boiler Size
Bigger isn’t always better, and smaller isn’t always cheaper.
One of the most common mistakes to avoid when buying a new boiler is choosing the wrong boiler size–and this is one that most first-time buyers tend to overlook.
How an Incorrectly Sized Boiler Affects Performance
An oversized boiler might seem like a good idea—after all, more power means better heating, right?
Well, not exactly.
A boiler that’s too large for your home will cycle on and off too frequently, leading to wasted energy, higher bills, and unnecessary wear and tear. This shortens the lifespan of your system and can leave you dealing with costly repairs sooner than expected.
On the other hand, a boiler that’s too small won’t be able to keep up with your heating and hot water demands. You’ll experience lukewarm showers, radiators that never quite get warm enough, and a system that’s constantly overworking itself to compensate. The result? Poor efficiency and an early boiler breakdown.
How to Avoid: The best way to ensure you get the right size is to have a professional heating engineer conduct a heat loss calculation.
At Rowlen, our team considers factors like the size of your home, insulation levels, and hot water usage to determine the perfect boiler capacity for your needs. We will lay out our recommended options so you would know how to choose the right boiler size. Contact our experts today!
Book a boiler quote
Call our specialists on 020 8395 8616 or fill in our booking form.
What Boiler Size Do You Actually Need?
Many homeowners don’t realise that boiler size isn’t just about the physical dimensions of the unit—it’s about output, measured in kilowatts (kW). Here’s a quick guideline:
- A small home or flat (1-2 bedrooms, 1 bathroom) typically needs a combi boiler with a 24-27kW output.
- A medium-sized home (3-4 bedrooms, 1-2 bathrooms) usually requires a combi boiler with a 28-34kW output or a system boiler with a 24-30kW output.
- A large home (4+ bedrooms, multiple bathrooms) benefits from a system boiler or conventional boiler with a 35-42kW output.
If you’re unsure whether a combi or regular boiler is right for you, consider whether you need instant hot water or have space for a hot water cylinder. A combi boiler is more compact but may struggle in homes with high hot water demand, whereas a regular boiler is ideal for properties with multiple bathrooms.
Related: Worcester Boiler Models Compared: Which One is Right for You?
2. Ignoring Energy Efficiency Ratings
Many homeowners ask, “Are new boilers more efficient?“
The answer is a resounding yes—modern boilers are designed to utilize condensing technology to recover and reuse heat from exhaust gases, advanced modulating burners to adjust fuel consumption based on demand, and smart heating controls to optimize energy use, resulting in lower fuel waste and higher efficiency ratings of 90% or more.
A high-efficiency boiler can save you up to £300 per year on energy bills, making it a worthwhile investment.
Most buyers ignore energy efficiency ratings because they often prioritize upfront costs over long-term savings, lack awareness of how efficiency impacts energy bills, or get overwhelmed by technical jargon when comparing boilers, leading them to focus on brand reputation or size rather than efficiency metrics.
If your boiler is over 10 years old, replacing it with a new A-rated model will significantly improve efficiency. Plus, the government often provides energy efficiency grants, so it’s worth checking if you qualify for funding to reduce the cost of new boiler installation.
How to Avoid: Always check the ErP (Energy-related Products) rating before buying a boiler. Look for an A-rated condensing boiler, such as the Worcester Bosch Greenstar 4000, Vaillant ecoTEC Plus, or Ideal Logic Max, which typically operate at 90% efficiency or higher. This means less wasted energy and lower heating costs over time.
Compare the Seasonal Efficiency of Domestic Boilers (SEDBUK) rating, if available, as it provides a more accurate efficiency measure across different conditions. By choosing a high-efficiency model upfront, like a Viessmann Vitodens 100-W or a Baxi 800, you’ll enjoy better performance, lower bills, and a more eco-friendly home. Invest wisely—it pays off in the long run!
Related: Best Combination Boilers for Every Budget in 2025
3. Not Verifying Your Installer’s Credentials
A high-quality boiler is only as good as the person installing it. Hiring an unqualified or inexperienced installer can lead to major safety hazards, inefficiency, and invalidated warranties.
The Importance of Hiring a Gas Safe Registered Engineer
Gas boilers must be installed by a Gas Safe registered engineer—no exceptions. This isn’t just a recommendation; it’s the law. Gas Safe heating engineers are trained to install, repair, and service boilers safely, reducing the risk of gas leaks and carbon monoxide poisoning. Not verifying your installer’s credentials is another one of the common mistakes to avoid when buying a new boiler, as poor installation can lead to inefficiency and safety hazards.
Before hiring anyone, check their Gas Safe ID card or verify their registration on the official Gas Safe Register. At Rowlen, every one of our engineers is fully qualified and highly experienced, ensuring your installation meets all safety regulations and industry best practices.
Related: Boiler Installation: Key Steps and Tips for a Smooth Process
4. Prioritising Upfront Cost Over Long-Term Value
One of the most common mistakes to avoid when buying a new boiler is choosing one based solely on upfront cost, without considering long-term efficiency and maintenance expenses.
A cheap boiler might seem like a bargain, but in reality, it could end up costing far more than a quality model over time. The cost of new boiler installation varies depending on the type, brand, and complexity of the setup, but investing in a high-quality system can save you money in the long term.
The True Cost of Choosing a Cheap Boiler
Budget boilers often use lower-quality components, which means they’re more likely to break down and require expensive repairs. They also tend to have shorter lifespans, meaning you’ll need a replacement sooner than expected.
A premium or mid-range boiler, on the other hand, is designed for durability, energy efficiency, and reliability. While the initial cost may be higher, the long-term savings on energy bills and repair costs make it a smarter investment.
5. Overlooking Smart Heating Controls
Technology has transformed home heating, but many homeowners still rely on outdated thermostats that waste energy and cost more in the long run.
Smart thermostats, like Nest or Hive, allow you to control your heating remotely, set schedules, and even use learning algorithms to optimise energy usage.
6. Skipping Regular Maintenance and Servicing
Buying a top-of-the-line boiler won’t mean much if you neglect it. Boilers need regular servicing to maintain efficiency, safety, and reliability. The average lifespan of a boiler is typically between 10 to 15 years, but regular servicing can help extend its longevity and efficiency.
How Regular Servicing Extends Boiler Lifespan and Performance
A well-maintained boiler operates more efficiently and safely, reducing the risk of costly breakdowns. Regular servicing involves:
- Checking for gas leaks and ensuring safe operation.
- Cleaning key components like the heat exchanger and burner to improve efficiency.
- Testing water pressure to ensure optimal heating performance.
- Identifying potential issues before they become expensive repairs.
Many manufacturers require annual servicing to keep a boiler warranty valid, making regular maintenance an essential part of protecting your investment.
Rowlen delivers excellent boiler servicing, backed by more than 5 decades of expertise and positive reviews from our satisfied customers. For regular boiler servicing, book online or call our experts at 020 8395 8616.
Related: Emergency Boiler Repair Near Me: Fast & Reliable Service Now
7. Failing to Consider Water Pressure and Home Heating Needs
Your home’s water pressure plays a big role in how well your boiler performs. Choosing a boiler that isn’t compatible with your water system can lead to frustrating performance issues. If you’re unsure whether to choose a combi or regular boiler, consider factors like household size, water pressure, and hot water demand to determine the best fit.
Before buying a new boiler, have a professional assess your home’s water pressure and heating demands to ensure you get the right system. High water pressure is ideal for combi boilers, while homes with lower pressure may need a system boiler with a separate cylinder to store hot water.
Related: How to Find the Best Plumbing Repair Near Me Service Quickly
Make the Right Choice with Rowlen
Choosing the right boiler is about more than just picking a brand or model. It’s about ensuring the system suits your home, is installed by experts, and is regularly maintained for years to come. Before making a final decision, go through a boiler replacement checklist to ensure you’ve considered all key factors, from size and efficiency to installation requirements.
At Rowlen, we bring over 50 years of expertise to every installation to help you get the best heating solution for your home. While there is no one-size-fits-all when it comes to buying a new boiler guide, our highly qualified heating engineers can assess your home’s needs and recommend the most efficient system–we’re here to provide expert guidance and reliable service!
For expert advice on your next boiler, get in touch with our team today. We’ll help you make the best choice for your home, budget, and comfort. Explore our list of areas covered to see if we offer services for your location.
