There are a number of factors to consider when buying a combi boiler. Price might be your first consideration. As with other consumer purchases, compromising on quality to reduce the initial cost may mean paying a price later in repairs and inconvenience. Cheap boilers are often difficult to repair and hard to find parts for, which means heating engineers may be reluctant to work on them.

Long-Term Peace of Mind
Long-term peace of mind is important to most boiler buyers. Some boilers offer up to 14 years of parts and labour warranty, meaning that if the boiler goes wrong, the manufacturer will fix it for free.

Minimum Heating Output
Another factor to consider is the minimum heating output. This means that the boiler can be adjusted to match the size of the heating system in your house. A combi boiler with a hot water output of 30 kW doesn’t need to work hard to heat your radiators. By lowering the heating output to match the size of your system, you will be wasting less energy. If your boiler’s minimum heating output can only be lowered to 10 kW, you’ll probably be burning more gas than necessary. The lower this number is, the more efficient your boiler.

What size boiler do I need? (theheatinghub.co.uk)

Hot Water Flow Rate
We also mention hot water flow rate, which is important when choosing your new combi boiler. Generally speaking, the higher the hot water output in kilowatts, the better the flow rate will be.

Let’s take a look at some of the most popular brands and see how they’re regarded by owners and installers. The scores shown against each manufacturer are taken from the Which? or Trustpilot websites, based on feedback from both installers and householders.

Worcester Bosch | Which? Score: 84%
Reviewers overwhelmingly had a great experience with this company. Customers consistently praise the company's service and products, highlighting their professionalism, efficiency, and knowledge of the engineers. Clear communication, helpfulness, and politeness of staff are also frequently noted.

Hot water flow rate: up to 16.4 l/min
Pros:

• Excellent reliability, highly recommended by Which?
• Parts widely available

Cons:

• Doesn’t work to maximum efficiency unless you use their own controllers
• Some repairs difficult

Common faults: Gas valve seizing, fan failure

Vaillant | Which? Score: 81%
Customers frequently commend engineers for efficient, knowledgeable, and friendly service. Reviewers often note individual engineers' professionalism, clear communication, and quick problem-solving.

Hot water flow rate: up to 15.9 l/min
Pros:

• Boilers very popular with users and engineers
• Easy to work on and parts widely available
• Excellent build quality and reliability

Cons:

• Fairly expensive
• Doesn’t work to maximum efficiency unless you use their own controllers

Common faults: Circuit board cutting boiler out, leaking diverter valve

Glowworm | Which? Score: 70%
The majority of reviewers reported highly positive experiences. Customers recognised the efficiency and quiet performance of Glow-worm boilers, frequently noting advantages over previous models or competing brands.

Hot water flow rate: up to 12.5 l/min
Pros:

• Cheaper to buy
• Good reliability

Cons:

• Build and component quality rated lower than other manufacturers
• Doesn’t work to maximum efficiency unless you use their own controllers

Common faults: Leaking diverter valve, circuit board failure

ATAG | Trustpilot Score: 4.8/5
Most reviewers report an excellent experience. Customers frequently commend the quality of products, pointing out efficient and quiet operation. Buyers also note reliability and a noticeable drop in energy costs.

Hot water flow rate: up to 16.1 l/min
Pros:

• High-quality parts
• Long warranty, lifetime warranty on main heat exchanger
• Heat recovery system for hot water adds efficiency

Cons:

• Historic problems with parts availability and aftercare (recently addressed)

Common faults: Unknown

Ideal | Which? Score: 77%
Ideal’s Logic and Vogue ranges run more cheaply than the average model. Most owners are satisfied, with a four-star customer rating.

Flow rate: up to 16 l/min
Pros:

• Very popular brand at an affordable price

Cons:

• Difficult to connect to the most efficient controllers
• Can become unreliable if not properly serviced

Common faults: Sump leaks, ignition problems

Baxi | Which? Score: 74%
Headquartered in Warwick, Baxi is one of the biggest boiler manufacturers in Europe, offering a lot of choice. Users have high satisfaction rates, resulting in a four-star customer score.
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Hot water flow rate: up to 16.4 l/min
Pros:

• Good value

Cons:

• Less well regarded by installers than many other brands
• Doesn’t work to maximum efficiency unless you use their own controllers

Common faults: Fan, burner, circuit board unit failure

A boiler is a long-term investment – and it needs regular care. Many homeowners forget to check what after-care is included, or skip servicing altogether.
​
Fix First Tip:
Choose an installer that offers ongoing support, annual servicing, and extended warranties. Ask if they offer service plans or maintenance contracts.

Modern boilers paired with smart controls can significantly improve efficiency and comfort. But many people stick with basic thermostats or don’t install proper heating controls at all.
​
Fix First Tip:
Invest in smart or OpenTherm-compatible controls. Options like Nest or Hive offer flexible programming and remote control – but check if they’re compatible with your boiler for full efficiency benefits.

Buying a new boiler doesn’t have to be overwhelming. By avoiding these common mistakes and asking the right questions, you can make a smart, informed choice that keeps your home warm, safe, and efficient for years to come.

At Fix First Heating, we believe in clear advice, honest pricing, and long-term customer care. If you’re ready to explore your options – or just want to ask a few questions – we’re here to help.

Need Help Choosing the Right Boiler? Get in touch with Fix First Heating today for friendly, no-pressure advice.

Loss of pressure on your boiler or heating system has only one cause: you have a leak.

The regularity of the pressure loss indicates the size of the leak. If you’re topping your pressure up hourly, the leak is significant. If it’s only every few weeks, it’s minimal.
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You can increase the pressure yourself on your boiler or heating system. But, if you have to do this regularly, there’s a problem that needs attention.

​A pressurised heating system has to be maintained at between 1-1.5 bar. If the pressure drops too low, it affects the performance of your heating.

You may find any of the following symptoms:

• The radiators don’t heat up properly: perhaps they are cold at the top, don’t heat up at all, or they are cooler than usual.
• The system may become louder as your heating pump may be struggling to circulate water effectively.
• The boiler may lock itself out and display a fault code.
• You may notice the boiler turning itself off and on more often than usual. This is called cycling and is caused by poor water flow through the boiler’s heat exchanger.

In this video we demonstrate how to put more pressure into your heating system using the filling taps below the boiler.

The pressure should sit between 1 – 1.5 bar. If the pressure falls below 1 bar, it needs topping up. If the pressure has risen above 2 bar, that’s a different issue that needs looking at.

The pressure is increased by putting water from your mains cold water pipe into the heating circuit. This is done from a filling device that will usually be in the airing cupboard or just below your boiler.

Combi boilers tend to have built-in filling devices. You should find the taps below the boiler on the right-hand side. There will be two taps that need to be gently opened up until the pressure returns to a normal level.

Each boiler has its own type of filling device. Check out our help videos for your boiler manufacturer: Ideal and Baxi/Potterton

On a system with a hot water cylinder, you’ll most likely find the filling loop in the airing cupboard. This will be a flexible braided silver hose between two valves that both need to be opened to pass mains water into the heating system.

Once or twice a year is about normal. If you’re doing it more often than this, especially during the winter months, when your heating is getting used often, then the boiler may need attention.

If you have to re-pressurise your boiler every day during the winter months, you probably have a deflated expansion vessel.

The pressure in your heating is regulated by a tank of compressed air somewhere on the system. Just like a car tyre, this needs regularly checking for the correct pressure. If the expansion vessel is empty, the pressure in your heating will start to fluctuate.

The pressure will rise as the water heats. If it gets to 3 bar, a safety valve opens, dumping pressure to a safe location. Once the water cools and contracts, the pressure will drop as low as 0 bar.
​
Continuing to top your pressure up without dealing with the fault will cause damage to your system. Constantly adding fresh, oxygenated water into radiators will cause rust and corrosion. Get the help of a heating engineer as soon as possible if you are experiencing this problem.

Usually, a leak is easy to find. Stains on carpets of flooring will be an obvious sign. There may be a leak on one of your radiators or the valves that connect to it.

Before calling a heating engineer, check all the radiators in your house for signs of rust or staining. Look under and around your boiler to see if there are any connections becoming scaled or grimy.

It’s also worth checking outside your house for the pressure-relief pipe. If this is dripping it could go unnoticed, especially if it’s located somewhere inconspicuous.

Components inside the boiler that commonly leak are the pressure relief valve or automatic air vent. These can be easily changed by a qualified heating engineer.

In some case the leak is on the heating pipework. This may be visible pipework leading to radiators, or hidden behind walls or above ceilings.
​
When heating pipework runs under solid floors, this can be expensive and very disruptive to repair. Your heating engineer may advise you to seek advice from a specialist leak detection company and to consult your insurance company.

If the leak is small and inaccessible, your heating engineer may recommend adding a leak sealing solution, such as Fernox F4, into the system. This uses a chemical to seal pinholes in the heating pipework without causing blockages.

When the leak is visible it can be repaired by replacing the faulty component. This might mean replacing a radiator valve, a boiler component, or renewing a section of your heating pipework.

It’s a good idea to seek help from your local reputable heating company before the problem gets worse.

Can’t find the leak on your system or struggling to get the help you need to fix it?

Ask your question in the box below and we’ll get back to you with our advice.

There are 3 basic types of boiler, which are available in gas or oil:

Combi boiler – directly heats both your heating and hot water

Heat only boiler – just heats the water to be supplied to your radiators and the hot water cylinder in your airing cupboard.
​
System boiler – similar to a heat only, but it contains the circulator pump within the boiler. It also allows for the small header tank in your loft to be removed.

Your house will have a certain amount of heat loss. Your system and boiler should match this rating to ensure they work most efficiently. Oversized boilers are inefficient as they deliver too much energy for the size of the system. Undersized boilers are ineffective as they won’t give you enough heat to make up for your house’s heat loss.

Ideally you should have a detailed heat loss survey on your house to ensure you’ve sized the boiler correctly. This obviously adds to the cost but may save you money in the long run. Most companies just look at the number of bedrooms and bathrooms in your house, then use their judgement on the boiler capacity. This method almost always results in oversizing.

​Boiler output is given in kilowatts. The higher the kilowatt output, the more expensive the boiler will be.

The quality of the boiler is the biggest determining factor in the cost of replacement. You can get some very cheap nasty boilers, which we do not fit and would never recommend. You’re entering a world of pain if you choose to fit a Ferroli, a Biasi, or something similar.

At the high end, you have brands such as Worcester, Vaillant and Atag. These companies have built a reputation for reliability and build quality.

Somewhere in the middle sit brands like Ideal and Baxi. If you’ve bought a new build house in the last 10 years, the chances are, it has an Ideal boiler.

​All boiler manufacturers offer some kind of reward scheme to their installers, so many companies will steer their clients towards their preferred brand. It’s wise to ask the engineer or sales person about other potential options.

You have a choice of 3 here. A full powerflush, a chemical cleanse, or a mains pressure flush.

A proper powerflush will take a full day to complete. It’s unlikely that any boiler quote you receive will include this.

A chemical cleanse is often used when new boilers are fitted. The engineer will add a cleaning chemical to the system and let it run for a while before draining the system to remove the dirty water. This is by far the cheapest option, but doesn’t clean the sludge out of your radiators very effectively,

​A system called Thoroughflush is sometimes used as an alternative to powerflushing. This uses mains-pressure water to clear debris from your system. It can target each radiator individually but takes a fraction of the time of a full powerflush.

Thermostats and programmers vary widely in quality.

Recent regulations require new systems to be fitted with higher efficiency controls. The most efficient controls use a system called OpenTherm. The control communicates the energy demand so the boiler can adjust its gas consumption and water temperature accordingly. These controls can often adjust heat output on the boiler according to outside air temperature, reducing heat demands in spring or autumn when the weather is mild.

With most boiler makes, you have to use the manufacturer’s own controls to benefit from this system.

​Smart thermostats, such as Hive or Google Nest also meet efficiency regulations and can be fitted to all systems. In most cases, they do not connect to your boiler using OpenTherm, so can only tell your boiler to turn on or off, making them less efficient.

Perhaps the hardest decision of all when buying a new boiler.

Most people rely on recommendations from friends and family to choose their installer. You’re more likely to get the personal touch from a local company. It also means that if any issues arise, you’re more likely to speak directly with an engineer. Checking reviews on Google or Facebook will give you a good idea of the reliability of these local companies.

​Some people opt for the perceived safety of a big company like British Gas or BOXT. This gives you the security of a large network of engineers, but the personal touch is lost. Should any problems occur, you’ll be calling a non-technical call centre operative.

​Like all large purchases for your home, choosing the right boiler is a big decision that will affect your home for many years. It’s important to research your options thoroughly and seek expert advice.

The quick answer is that, on average, a boiler will last between 10 and 15 years. But this will depend on various factors, including your usage, the type of boiler you have, water quality, and level of maintenance. With the right level of care, a boiler could last up to 20 years.

It’s easy to take your boiler for granted and only really worry when you have no hot water or the heating fails to come on in the Autumn. So, what elements can affect the lifespan of your boiler?

Three key factors that affect your boiler’s lifespan

1. The type of boiler 
   Different boilers have varying lifespans because of the design and components that can influence their durability. For example, a combi boiler may last between 10 and 12 years, while a conventional boiler could last 15 years or more. A qualified heating engineer can advise you on the best option for your needs.
   
   
2. Regular maintenance
   Regular servicing will identify minor issues before they become bigger and more expensive to fix. The checks undertaken include identifying leaks, ensuring correct pressure, and cleaning components. Boilers serviced by qualified heating engineers tend to last longer. 
   
   
3. Usage and water quality
   Boilers in homes with high hot water demand or those running constantly during the cold months may wear out faster than those in homes with lower demand. Equally, limescale can build up and reduce boiler efficiency in areas with hard water. Installing a water softener can help combat this problem. 

Looking out for these signs can help you when your boiler has an issue or is nearing the end of its life.

Danger signs for the lifespan of your boiler

• When you hear unusual noises coming from your boiler, you may have a problem. These could be banging, clunking or whining, indicating additional pressure being placed on some internal parts, which can be down to wear and tear.
  
  
• You may see signs of leaking or dripping in and around your boiler. Often, this can indicate corrosion or pressure issues, which means your boiler is not running as it should.
  
  
• Maybe you need to call a heating engineer for frequent breakdowns. It is not an ideal situation, and it is often inconvenient. It shows your boiler is struggling and may need a service or replacement.
  
  
• You have increased energy bills. An old or inefficient boiler must work harder to maintain output, meaning higher energy usage.
  
  
• Reduced efficiency. Your boiler is not heating your home or water as effectively as it once did, indicating you have an issue.

Before you get to the stage of experiencing any of these danger signs, there are other ways you can extend the lifespan of your boiler. These are relatively easy to take up, and if you work with a qualified heating engineer, they will be happy to help.

How to extend the lifespan of your boiler

Schedule an annual service with a Gas Safe registered engineer to ensure your boiler lasts as long as possible. Companies such as Fix First Heating offer maintenance packages, which means you can spread the cost of servicing over a year through low-cost monthly payments. It also gives you peace of mind knowing if there is an issue during the year, they will schedule a visit and fix it for you.

Checking your pressure levels on the boiler will help you identify any issues as early as possible. Ask your heating engineer to show you how to do this. Fix First Heating is always happy to do this. Once you know where to look, it’s a relatively easy job. 

Over time, boilers accumulate sludge and debris in the system. If this happens, it can be detrimental to the efficiency of your boiler and, over time, will bring the system to a standstill. Installing a magnet filter is a straightforward way to reduce the build-up of unwanted particles. 

Living in a hard water area can also cause issues with your boiler. Limescale can be deposited in the system and have a similar effect. A water softener will reduce this kind of debris.

Finally, boilers have pipework, which can freeze in the cold winter months. Insulating your pipes can prevent freezing and potentially the damage this can cause. Not least, it can keep your boiler working when you need it most!

When should I consider replacing my boiler?

Sometimes, it just isn’t possible to continue repairing an old boiler. Regular maintenance will extend its life, but most homeowners opt for a replacement after about 15 years. The newer models are very energy efficient, meaning you would save on your energy bills, and the performance would be much more reliable. So, if your boiler breaks down frequently, appears less efficient, or is over 15 years old, investing in a new one may be more cost-effective. 

With the right level of maintenance in place, your boiler can last up to 20 years. Regular servicing and dealing with any minor issues promptly can help ensure your boiler runs efficiently for as long as possible. 

If you’re unsure about the condition of your boiler or worried about breakdowns, get in touch with Fix First Heating. We offer a range of services that will give you peace of mind.

Choosing the right boiler for your house is a big decision. You want your boiler to give you years of reliable service, so getting the right one for your property is important.

As with most other things, you get what you pay for, so its never advisable to go for the cheapest boiler you can find.

We would always recommend choosing from one of the most trusted and renowned manufacturers.

To help you make an informed choice about your next boiler, we have reviewed 3 of the best quality boiler brands on the market.
 
Worcester Boilers

Overview:
Worcester Bosch is a highly regarded brand in the boiler industry, known for its reliable and efficient products. They offer a range of boilers for all homes of all sizes.

Performance and Efficiency:
Worcester boilers are praised for their high efficiency and robust performance. They typically feature a high efficiency rating (90% and above) and have received numerous accolades for their innovation and energy-saving capabilities.

Customer Feedback:
According to Which? reviews, Worcester Bosch consistently receives high ratings for reliability and customer satisfaction. Trustpilot reviews echo this sentiment, with many users highlighting the long lifespan, minimal maintenance needs, and excellent customer service.

Pros:

• High efficiency
• Reliable and durable
• Excellent customer service

Cons:

• Higher initial cost compared to some competitors

Vaillant Boilers

Overview:
Vaillant is another leading boiler manufacturer, recognised for its commitment to quality and sustainability. They provide a diverse range of boilers suitable for various household needs.

Performance and Efficiency:
Vaillant boilers are known for their efficiency and environmental friendliness. They often incorporate advanced technology to reduce energy consumption and carbon footprint. Many models boast an efficiency rating of over 90%.

Customer Feedback:
Which? reviews rate Vaillant boilers highly for their reliability and ease of use. On Trustpilot, customers generally appreciate the efficient performance and quiet operation of Vaillant boilers. However, there are occasional mentions of installation challenges and the need for professional servicing.

Pros:

• Energy-efficient
• Environmentally friendly
• Quiet operation

Cons:

• Installation can be complex
• Professional servicing recommended for optimal performance

Atag Boilers

Overview:
Atag is a premium boiler brand that emphasises high-quality engineering and innovative design. They offer an industry-leading 18-year warranty on their boilers, as well as lifetime warranty on their stainless steel heat exchangers.

Performance and Efficiency:
Atag boilers are renowned for their exceptional efficiency, often achieving ratings well above 90%. They incorporate innovative technology to ensure optimal performance and energy savings.

Customer Feedback:
Which? reviews highlight Atag boilers for their reliability and superior build quality. Trustpilot reviews are generally positive, with customers praising the long-term performance and efficiency. However, some users mention that Atag boilers can be more expensive upfront and may require more specialised maintenance.

Pros:

• Superior efficiency
• Innovative design
• High build quality

Cons:

• Higher upfront cost
• Specialised maintenance may be required

Conclusion

When choosing between Worcester, Vaillant, and Atag boilers, each brand offers distinct advantages:

• Worcester Bosch stands out for its reliability, excellent customer service, and overall high customer satisfaction. It is ideal for those looking for a durable and efficient boiler with strong after-sales support.
• Vaillant excels in energy efficiency and environmentally friendly features. It is a great choice for eco-conscious consumers seeking a quiet and efficient boiler.
• -Atag offers premium quality and innovative design, making it suitable for users willing to invest in a high-end boiler with exceptional efficiency.

Ultimately, the best choice depends on individual preferences and specific needs, such as budget, desired features, and the importance of customer service. It is always best to discuss the most suitable boiler type and brand with heating adviser.