System Boiler vs Regular Boiler

Deciding on a boiler for your home is one of the most important choices you will make in regard to your home heating system. These days, energy efficiency is at the forefront of many people’s minds with energy prices at all-time highs, so it is vital that you select a boiler that will best fit your household and budget.

In this in-depth article we are going to be discussing the differences between a system boiler and a regular boiler in order to better inform your decision when making that next boiler purchase.

Understanding Regular Boilers: The Traditional Choice

Regular boilers are also known as conventional, traditional or heat only boilers and have been heating British homes for many years. The unit will be connected to a cold water storage tank, usually in the loft and to a hot water cylinder, usually in an airing cupboard.

Cold water is taken from the storage tank, passed through the boiler where it is heated and stored in the hot water cylinder ready for use. As the water is already heated, when you turn on a hot tap or your central heating system the hot water is instantly available.

How Regular Boilers Operate

A regular boiler works in this way. Cold water enters your home and is stored in a tank in your loft. It feeds down to the boiler by gravity, where it is heated and then pumped to the hot water cylinder. A feed and expansion tank in the loft ensures the heating system has the correct pressure of water in it, and allows for expansion when the water is heated.

A traditional system like this takes up a lot of space, but does have some advantages.

What Makes System Boilers Different?

System boilers represent a more modern approach to home heating. Whilst they still require a hot water cylinder, they eliminate the need for a cold water storage tank in the loft. This is because system boilers take water directly from the mains supply, with most major components built into the boiler unit itself.

The key distinction lies in how these boilers manage water pressure and storage. System boilers include an expansion vessel and pump within the unit, reducing the number of external components needed. This makes installation cleaner and more straightforward whilst maintaining many benefits of traditional systems.

The Mechanics Behind System Boilers

System boilers heat water directly from the mains and store it in a cylinder for later use. The integrated pump ensures efficient circulation throughout your heating system, whilst the built-in expansion vessel manages pressure changes safely. This compact design means fewer components to maintain and less space required in your loft.

Because they’re sealed systems, there’s less risk of frost damage or contamination compared to open-vented regular boilers.

Key Differences That Matter

Understanding the practical differences between these two boiler types will help you make the right choice for your circumstances.

Space Requirements

Regular Boilers Need:

• A cold water storage tank in the loft (typically 227 litres)
• A feed and expansion tank in the loft
• A hot water cylinder (usually in an airing cupboard)
• The boiler unit itself
• Adequate loft space with proper support for heavy water tanks

System Boilers Require:

• A hot water cylinder only
• The boiler unit with integrated components
• Significantly less loft space
• No overhead water storage

This difference becomes crucial in properties with limited loft space or converted lofts where water tanks simply aren’t practical.

Water Pressure Considerations

Regular boilers rely on gravity to create water pressure, which means the higher your cold water tank sits above your taps, the better the pressure. This can result in disappointing shower performance unless you install a pump.

System boilers, drawing directly from the mains, typically provide stronger and more consistent water pressure throughout your home. Multiple taps can run simultaneously without significant pressure drops, making them ideal for busy family bathrooms.

Installation Complexity and Cost

Installing a regular boiler tends to be more involved, especially in properties that don’t already have the necessary tanks and cylinders. The installation requires careful planning, proper loft support, and extensive pipework.

System boilers generally offer simpler installation, particularly when replacing an existing system. With fewer external components, the work can often be completed more quickly, potentially reducing labour costs. However, if you’re converting from a regular to a system boiler, you may need additional work to remove old tanks and upgrade pipework.

Advantages of Regular Boilers

Despite being the older technology, regular boilers continue to serve many UK homes effectively.

Proven Reliability

Regular boilers have decades of proven performance behind them. Their straightforward mechanics mean that many heating engineers are intimately familiar with repairs and maintenance. Parts are widely available, and the systems are well understood.

Multiple Outlet Performance

With a large cylinder of pre-heated water available, regular boilers can supply multiple taps simultaneously without running out of hot water quickly. This makes them particularly suitable for larger households where several people might want baths or showers at similar times.

Lower Mains Pressure Requirements

In areas where mains water pressure is poor or inconsistent, regular boilers don’t rely on this supply for operation. They can function effectively even with modest mains pressure, as they create their own system through gravity feed.

Compatibility Benefits

Many older properties were designed with regular boilers in mind. If your home already has the necessary tanks and cylinders in good condition, replacing like-for-like can be the most cost-effective option.

Benefits of Choosing a System Boiler

Modern system boilers offer several compelling advantages for today’s homeowners.

Space Efficiency

By eliminating loft tanks, system boilers free up valuable space. This is particularly beneficial if you’re planning a loft conversion or simply want to use your loft for storage. The reduced footprint makes them suitable for properties where space is at a premium.

Faster Installation

With fewer components to install, system boilers can often be fitted more quickly than regular boilers. This means less disruption to your daily routine and potentially lower installation costs.

Better Water Pressure

The mains-fed design typically delivers superior water pressure, making for more satisfying showers without the need for additional pumps. This consistent pressure throughout the system is one of the most noticeable improvements when upgrading from a regular boiler.

Reduced Maintenance Concerns

Without loft tanks to worry about, there’s no risk of frost damage to exposed pipes or tanks during cold winters. There’s also no possibility of contamination from debris entering open tanks, leading to cleaner, fresher water.

Energy Efficiency

Many modern system boilers achieve high efficiency ratings, with condensing models converting more of the fuel into usable heat. This can translate to lower energy bills and reduced carbon emissions compared to older regular boilers.

Which Properties Suit Each Boiler Type?

Regular Boilers Work Best For:

• Large Period Properties: Victorian and Edwardian homes with existing cylinder systems and generous loft space
• Homes with Poor Mains Pressure: Properties in rural areas or locations with inadequate mains water pressure
• Multiple Bathroom Properties: Larger families requiring simultaneous hot water access at several outlets
• Listed Buildings: Where maintaining traditional systems may be preferred or required
• Properties with Low Flow Rates: Where the mains supply cannot deliver sufficient volume for a system boiler

System Boilers Excel In:

• Modern Homes: New builds and recently renovated properties designed for efficiency
• Converted Lofts: Homes where loft space has been reclaimed for living areas
• Medium-Sized Families: Properties with two to three bathrooms requiring good pressure
• Areas with Strong Mains Pressure: Locations with reliable mains water supply
• Space-Conscious Homes: Properties where maximising usable space is important

How Local Boiler Helps You Make the Right Choice

Local Boiler are happy to offer advice and make recommendations on what the best option for you is. We have been trained and have heard the same questions time and time again, so we understand how daunting and confusing the whole process can be. We are also not here to make sales pitches and recommend certain products, we will instead listen to what you are saying and what your requirements are in terms of property size, existing set up and your family needs.

A certified Local Boiler heating engineer will be able to assess the mains water pressure on your property, carry out a survey on your existing system and discuss with you what the most efficient and cost-effective option is for your specific needs. Whether you need to replace an old and faulty boiler, or a new boiler and complete re-wire, Local Boiler are happy to advise you on your best options and most realistic pricing, as well as carrying out the installation for you.

Running Costs and Efficiency Factors

Both boiler types can be highly efficient when properly specified and maintained, but there are nuances to consider.

Energy Efficiency Ratings

Modern condensing system boilers typically achieve efficiency ratings of 90% or higher, meaning very little heat is wasted. Regular boilers can also be highly efficient if they’re condensing models, though older units may operate at lower efficiency levels.

The key factor isn’t necessarily the boiler type but rather the age and specification of the unit. A new regular boiler will vastly outperform an old system boiler, and vice versa.

Heat Loss Considerations

Regular boilers with loft tanks may experience some heat loss through the hot water cylinder and pipework. Proper insulation can minimise this, but it remains a consideration. System boilers face similar heat loss from the cylinder but eliminate any losses from loft tanks and associated pipework.

Maintenance Requirements

Both systems require annual servicing to maintain efficiency and safety. However, regular boilers have more components that could potentially require attention, including ballvalves in loft tanks, multiple thermostats, and additional pipework connections.

System boilers, with their more integrated design, may have slightly lower long-term maintenance costs due to fewer external components.

Installation Timescales and Disruption

Understanding what’s involved in installation helps you plan appropriately.

Regular Boiler Installation

Installing a new regular boiler in a property already set up for one typically takes two to three days. This includes removing the old boiler, installing the new unit, and making all necessary connections to existing tanks and cylinders.

If tanks or cylinders need replacing, or if you’re installing a regular boiler system from scratch, the work could extend to four or five days. Loft access needs to be safe and adequate, and the structure must support the weight of full water tanks.

System Boiler Installation

A straightforward system boiler replacement usually takes one to two days when replacing an existing system. The streamlined installation process means less time without heating and hot water.

Converting from a regular boiler to a system boiler involves additional work to remove loft tanks and potentially upgrade pipework, which might extend the installation to three days.

Making Your Decision: Key Questions to Ask

Before choosing between a system and regular boiler, consider these important questions:

• What’s your mains water pressure like? Low pressure may make a regular boiler more practical, whilst good pressure suits system boilers perfectly.
• How much loft space do you have? Limited or converted loft space points towards a system boiler.
• What’s currently installed? Sometimes the most economical choice is replacing like-for-like if your current system meets your needs.
• How many bathrooms do you have? Larger properties with multiple bathrooms need careful consideration of hot water demand.
• What are your future plans? If you’re planning a loft conversion, installing a system boiler now makes sense.
• What’s your budget? Consider both installation costs and long-term running costs in your decision.

Local Boiler can help you work through these questions systematically, ensuring your final choice aligns with both your immediate requirements and long-term plans. Their experience across thousands of installations means they’ve encountered virtually every property type and heating challenge.

The Importance of Professional Installation

Whatever boiler you decide to go with, it’s critical to have it installed by a professional. Gas boilers in particular must be installed by Gas Safe registered engineers, and the quality of an installation will have a massive impact on performance, efficiency and safety.

A poor installation can cause all sorts of issues from poor efficiency to premature component failure, safety issues and even voided warranties. The small extra cost to have a budget installer over a quality professional will pale in comparison to the issues caused by a poor job.

Always check Gas Safe registration, reviews and references, ask for detailed written quotations, and ensure suitable guarantees are in place for both equipment and workmanship. All of the above is maintained by Local Boiler, and we will be happy to show you all the certifications we have, and our full guarantees on all our work will give you the peace of mind you need to know your installation is safe and of the highest quality.

Future-Proofing Your Heating System

If you’re planning to install a new boiler, future-proofing is something to keep in mind. The government has already announced that gas boilers will be banned in new homes by 2025. It also has an ambitious long-term target of achieving net-zero emissions.

While there’s no rush to ditch your current gas boiler, it’s still sensible to consider future-proofing. For example, both system and regular boilers are compatible with solar thermal panels. System boilers are also typically more compatible with modern heating controls and smart home systems.

Of course, it’s important to keep in mind how long you intend to stay in your property before investing. If you plan to be there for a while, it’s worth asking heating professionals for advice on future-proofing your investment.

Also Read: L2 on Boiler: What It Means and How to Fix It

Common Misconceptions Clarified

Several myths persist about these boiler types that are worth addressing.

1. Myth: System boilers always cost more to run. Reality: Running costs depend on efficiency ratings and usage patterns, not boiler type alone.
2. Myth: Regular boilers are outdated and inefficient. Reality: Modern regular boilers can be just as efficient as system boilers when properly specified.
3. Myth: You must replace like-for-like. Reality: Converting between boiler types is entirely possible when it makes sense for your property.
4. Myth: System boilers provide unlimited hot water. Reality: Both types have limited hot water capacity determined by cylinder size.
5. Myth: Regular boilers are cheaper overall. Reality: Total costs depend on your specific installation requirements and existing infrastructure.

Final Thoughts

The decision between a system and regular boiler is not a case of one being better than the other. Instead, it is about working out which one is more suited to the specific property, the lifestyle of the occupants and the budget available. For many homes, especially larger properties that already have the right infrastructure and space, a regular boiler will continue to be the ideal choice. For other homes where the convenience of a modern boiler, space-saving design and reliable water pressure are higher priorities, a system boiler is an attractive option.

The key factor is getting a professional assessment and tailored advice based on your own particular needs and circumstances. Boiler recommendations will only be truly helpful if they are informed by factors unique to your property, such as mains water pressure, pipework, number of occupants and daily routines.

Armed with an understanding of the key differences between these boiler types, and in the hands of experienced, customer-focused professionals who will always put your needs before sales targets, the final choice can be made with confidence and will provide you with efficient, reliable heating and hot water for years to come. A boiler is a significant investment in your home comfort, and taking the time to make a decision you will be happy with will pay dividends over the lifespan of the system.

Frequently Asked Questions

Can I convert from a regular boiler to a system boiler?

Yes, converting from a regular boiler to a system boiler is entirely feasible and quite common. The process involves removing the cold water storage tanks from your loft, capping off redundant pipework, and connecting the new system boiler to the mains water supply.

How long does a hot water cylinder last with each boiler type?

Hot water cylinders typically last 15 to 25 years regardless of whether they’re connected to a regular or system boiler. The longevity depends more on water quality, maintenance, and the cylinder’s build quality than the boiler type. 

Will a system boiler work if there’s a power cut?

System boilers require electricity to operate the pump and controls, so they won’t function during a power cut. However, this limitation also applies to regular boilers, as they too need electricity for controls, pumps, and the boiler’s ignition system. Neither system will provide heating or hot water without mains power.

Which boiler type is better for hard water areas?

Both regular and system boilers can work effectively in hard water areas, though hard water poses similar challenges for each system. Scale buildup from minerals in hard water can affect heat exchangers, reduce efficiency, and damage components over time. The key difference is that system boilers draw directly from the mains, potentially exposing the boiler’s components to hard water more directly. 

How much space does a hot water cylinder require?

Hot water cylinders typically require a footprint of approximately 60cm by 60cm and stand between 90cm and 180cm tall, depending on capacity. The space needed is essentially the same whether you’re using a regular or system boiler, as both require a cylinder. Most cylinders are installed in airing cupboards, utility rooms, or dedicated cupboards on landings.