Heat Only Boilers

Heat Only Boilers

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All You Need to Know About Heat-Only Boilers

Are you considering choosing one of the heat-only boilers for your home? You’ve come to the right place! This comprehensive guide will explore everything you need to know about heat-only boilers, including their components, how they work, and how they compare to other boiler types. We’ll also offer tips for choosing the right boiler, discuss installation and costs, delve into energy efficiency and eco-friendly options, and provide maintenance advice for optimal performance.

Key Takeaways

  • Heat-only boilers are economical and effective for providing central heating and hot water.
  • Consider size, insulation level, and number of radiators/hot taps/showers when selecting the right boiler for your home.
  • Regular maintenance is essential for optimal performance, energy efficiency, safety & longevity with an expected 10-15 years lifespan.

Lady does a comparison of a heat only boiler and a combi boiler on her ipad

Understanding Heat-Only Boilers

A heat-only or conventional boiler supplies central heating and hot water by heating water in a separate hot water cylinder and distributing it throughout the property. Conventional boilers have three main components: the boiler, a hot water storage cylinder, and a cold water storage tank.

The operation of these boilers, alternatively known as regular boilers, occurs as the boiler heats water and transfers it to a hot water cylinder for storage. This hot water is then circulated through the property when required. These boilers are appreciated for their ability to provide consistent central heating and hot water and cost-effectiveness.

However, the primary disadvantage is the need for space in the home.

Key Components of Heat-Only Boilers

A central heating system typically includes a heat-only boiler system, which consists of:

  • The boiler itself
  • A hot water storage cylinder
  • A cold water storage tank (in open-vented systems)
  • Radiators or underfloor heating system
  • Pipework and valves for water circulation

The optimal size of a heat-only boiler, which typically uses gas heat, is determined by the number of bathrooms, hot water outlets, and radiators present in a property.

Boilers have the following features:

  • Use a feed and expansion tank to sustain water pressure
  • Have supplementary tanks, usually located in the loft
  • Can provide hot water and central heating to multiple bathrooms, even with a low flow rate from the main water supply
  • Are an excellent fit for homes with a high demand for hot water

How These Boilers Work

Heat-only boilers differ from system boilers in utilising a feed and expansion tank to sustain pressure. In contrast, system boilers employ a pressurized heating circuit replenished by mains water. These boilers are particularly suitable for properties with low water pressure or flow rates, as their open-vented systems can provide simultaneous hot water and central heating to multiple bathrooms.

Furthermore, heat-only boilers are a great choice for properties with old radiators, as they will not cause them to leak or malfunction. In the event of a boiler malfunction, having a backup hot water supply in a heat-only boiler provides continuous hot water service.

A homeowner reviewing a new boiler replacement quote, considering boiler warranties and upfront costs

Comparing These Boilers with Other Types

Regarding their differences and advantages, heat-only boilers can be compared to combi and system boilers. Combi boilers are compact units that instantaneously furnish heating and hot water without requiring a separate cylinder. In contrast, system boilers are similar but feature an integrated expansion vessel and pump, making them more efficient.

Heat-only boilers are typically cheaper to install than combi and system boilers, but

Heat Only vs. Combi Boilers

Compared to combi boilers, heat-only boilers are more economical as they eliminate the need for installing a hot water cylinder. They also offer more placement flexibility, as they aren’t required to be near a hot water source.

On the other hand, a combi boiler is suitable for smaller properties with lower hot water requirements, as combi boilers provide hot water on demand.

Regarding suitability for varying property sizes and hot water requirements, these boilers are more suitable for larger properties with greater hot water needs. Compared, combi boilers are better suited for smaller properties with lower hot water needs.

Heat Only vs System Boilers

A heat-only boiler necessitates a feed and expansion tank, a cold water cistern, and a hot water storage cylinder. On the other hand, system boilers supply hot water instantly and heat without requiring additional tanks. They are physically much less bulky than traditional boilers. There is no need for tanks and heavy-duty piping as they do not require open vent systems..

While these boilers are more cost-efficient, as they do not require additional components like an expansion vessel and pump, system boilers can store hot water for extended periods of time, making them more efficient overall.

Choosing the Right Boiler

Selecting the most suitable boiler for your home involves determining the perfect boiler size, which depends on your home’s size, radiators, and hot taps/showers.

Top brands and models include Viessmann, Worcester Bosch, Vaillant, and Ideal.

Determining the Ideal Boiler Size

The dimensions of a boiler hinge on the size of the property and its insulation level. A boiler size calculator or a consultation with a heating professional can help pinpoint the exact boiler size needed. When selecting an appropriate boiler size, consider the size of the property, the number of radiators, and the number of hot taps and showers.

It is important to strike a balance between choosing a boiler that is too small, which may struggle to meet your heating and hot water demands, and one that is too large, which can lead to energy waste and higher energy bills.

Top Brands and Models

Well-known boiler brands include Viessmann, Worcester Bosch, Vaillant, Potterton, and Ideal. Some standout models are the Worcester Bosch Greenstar 8000 Life Regular Boiler, Vaillant ecoTEC plus Regular, and the Ideal Logic+ Heat Only Boiler. These top brands and models offer energy efficiency, low emissions, and quiet operation.

However, they tend to have higher initial costs and require regular maintenance. It is essential to weigh the advantages and disadvantages of each brand and model to determine which boiler best suits your needs and preferences.

A gas safe registered engineer performing an annual boiler service to ensure maximum efficiency and safety.

Installation and Costs

Hiring professional plumbers or installers is advised regarding the installation process and costs associated with these boilers, as most boiler retailers can assist with installation.

Delivery and installation services may be included in the purchase, and you might be able to find a boiler delivery system that offers free delivery of tanks.

Typical Installation Process

Removing a heat-only boiler entails disconnecting it from the system and physically removing it from the premises. Afterwards, the system needs flushing, which involves draining and refilling all the water with fresh water. When installing the new boiler, it is important to connect it to the system, verify the system, and confirm that all safety protocols are in place.

If your property has pre-existing water tanks, ensuring they are in satisfactory condition and compatible with the new boiler is essential. This can streamline the installation process and minimize costs.

Cost Factors and Financing Options

Expenses associated with these boilers encompass the Value-Added Tax, delivery fees, and installation costs. Various financing options exist for these boilers, such as 0% APR financing, bank loans, and boiler grants, to make the purchase more affordable. Examining these options and selecting the one that best aligns with your financial situation is advisable.

Remember that investing in a more energy-efficient boiler can lead to long-term savings on energy bills, offsetting the initial costs of the boiler and installation.

Energy Efficiency and Eco-Friendly Choices

For those keen on energy efficiency and sustainable boiler options, strategies like installing a more efficient boiler, setting up a programmable thermostat, and insulating your home effectively decrease the energy costs linked with these boilers.

Top eco-friendly models include the Worcester Bosch Greenstar 30i, the Baxi EcoBlue Advance Heat, and the Vaillant ecoTEC Plus.

Reducing Energy Bills with Efficient Boilers

This boiler offers several energy efficiency benefits, such as:

  • Lower heating bills
  • Higher efficiency percentage
  • Reduced carbon footprint
  • The use of condensing technology

Proper insulation is crucial in preventing heat loss and improving energy efficiency to reduce energy bills further. Insulation materials such as foam, fibreglass, and cellulose are recommended for these boilers.

Regular maintenance is also essential in ensuring your boiler’s optimal performance and energy efficiency. This includes checking the pressure, cleaning the filters, and inspecting the flue for blockages or leaks.

Top Eco-Friendly Models

Eco-friendly boilers are designed to be energy efficient and reduce energy consumption. The Elnur Mattira MAC15 and electric boilers are considered to be the most eco-friendly models of boilers. The Elnur Mattira MAC15 boasts a high-efficiency rating of 92%, while electric boilers are 100% efficient.

Both models are designed to minimize energy consumption and maximize savings on energy bills. By choosing one of these eco-friendly boiler models, homeowners can make a more environmentally conscious choice while enjoying long-term savings on energy bills.

Maintenance and Longevity

Maintaining your boiler properly ensures its performance, energy efficiency, safety, reliability, and longevity. A system boiler requires similar maintenance to achieve the same results.

A heat-only boiler is typically expected to last between 10 and 15 years, with the specific lifespan varying based on the model and the quality of maintenance.

Regular Maintenance for Optimal Performance

To ensure the optimal performance and energy efficiency of your heat-only boiler, it is recommended to:

  1. Have it serviced regularly by a qualified engineer.
  2. Monitor the pressure of the boiler and top it up if necessary.
  3. Inspect the boiler for any signs of corrosion or leaks.
  4. Clean the filters as needed.

Following these maintenance tasks will help prolong the lifespan of your heat-only boiler and maintain its performance, ensuring you get the most out of your investment.

Expected Lifespan and Warranty Options

The anticipated lifespan of a  boiler may differ. However, it is estimated to last up to 15 years on average. Proper maintenance is crucial in extending the lifespan of your boiler and ensuring its optimal performance.

When purchasing a heat-only boiler, you must inquire about warranty options available for added peace of mind. Most boilers come with a manufacturer’s warranty of up to two years, while additional warranties can be acquired from the manufacturer or a third-party provider.


In conclusion, heat-only boilers are reliable and cost-effective for providing your property with central heating and hot water. By understanding their components, operation, and how they compare to other boiler types, you can make an informed decision when choosing the right boiler for your home. With proper installation, maintenance, and eco-friendly choices, a boiler can offer long-term savings on energy bills and contribute to a more sustainable future.

Frequently Asked Questions

Are these boilers any good?

Heat-only boilers offer the benefit of large hot water storage capacity, which makes them ideal for larger homes and multiple taps. They also work well in systems divided into multiple heating zones or requiring larger pumps than normal. Ultimately, these boilers can be great for larger home heating systems.

What are the disadvantages of a heat-only boiler?

Heat-only boilers can be problematic due to limited hot water availability, as they draw from a cylinder rather than the mains. They can also struggle to meet high demand, potentially increasing running costs. To combat this, it is important to ensure that the boiler is the correct property size and is regularly serviced. Additionally, installing a hot water booster pump can help to increase the flow rate and reduce the

How much does it cost to fit this type of boiler?

The cost for fitting a boiler of this type typically ranges from £1,800 to £3,200, depending on the specific model and installation time.

What is a heat-only boiler?

A heat-only boiler, a regular, conventional or open vent boiler, is a system used to provide central heating and hot water in many UK homes built before the 1970s. It involves two tanks, a hot water cylinder and the boiler itself and is best suited to larger properties with low water pressure.

What are the main components of a heat-only boiler?

A heat-only boiler comprises a boiler, a hot water storage cylinder and a cold water storage tank, making up the core components of this system.

Disclosure: This post contains affiliate links, including Amazon Associate links, through which I earn from qualifying purchases at no extra cost to you.

I only recommend products I genuinely believe in. Visit my Privacy Policy page for more information.


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