Last updated: May 29th, 2023 at 04:31 am

A heat only boiler, also known as a regular or conventional boiler, is a type of boiler that is specifically designed to provide heating for a property. It is called “heat only” because its primary function is to generate heat for the central heating system, without providing hot water for domestic use.

Heat only boilers are commonly found in older properties that have traditional heating systems, such as radiators and a separate hot water cylinder. They work by heating water and circulating it through the radiators to provide warmth to the rooms.

Unlike combi boilers or system boilers, heat only boilers do not have an integrated hot water storage tank. Instead, they require a separate hot water cylinder, often located in an airing cupboard or elsewhere in the property. This cylinder stores and supplies the domestic hot water to taps, showers, and other hot water outlets.

Heat only boilers are usually connected to a cold water storage tank (also known as a feed and expansion tank) in the loft. This tank supplies cold water to the boiler, which is then heated and circulated through the radiators.

feed and tank boiler heat only diagram

Boiler heat only systems have been a popular choice for heating residential and commercial spaces. In this blog post, we will explore the advantages, disadvantages, and important factors to consider when opting for a boiler heat only system. Whether you are considering a new installation or contemplating a switch, this guide will provide you with valuable insights to make an informed decision.

heat only boiler working diagram

Pros of Boiler Heat Only Systems

  1. Energy Efficiency: Boiler heat only systems are known for their high energy efficiency. By effectively utilizing the fuel source, they can provide efficient heating, resulting in potential energy savings and reduced utility bills. This efficiency is particularly advantageous in colder climates or regions with long heating seasons.
  2. Even and Comfortable Heat Distribution: One of the significant advantages of boiler heat only systems is their ability to provide even heat distribution. Through the use of radiators or underfloor heating, these systems ensure that every corner of your space is kept comfortably warm, eliminating cold spots and drafts.
  3. Domestic Hot Water Supply: Many boiler heat only systems are designed to provide domestic hot water in addition to space heating. This integration eliminates the need for separate water heaters and allows for a streamlined and efficient heating system.
  4. Compatibility with Radiators and Underfloor Heating: Boiler heat only systems seamlessly integrate with traditional radiators and modern underfloor heating systems. This flexibility provides homeowners with options to choose the heating method that best suits their preferences and requirements.
  5. Reduced Risk of Airborne Allergens: Unlike forced-air heating systems that circulate air, boiler heat only systems do not blow air around. This characteristic reduces the risk of airborne allergens, making them a preferred choice for individuals with respiratory sensitivities or allergies.

Cons of Boiler Heat Only Systems

  1. Initial Installation: Cost The upfront cost of installing a boiler heat only system can be higher compared to other heating systems. This is due to the complexity of the installation process, including the need for pipework, radiators, and potentially underfloor heating systems. However, it’s essential to consider the long-term energy savings and efficiency benefits.
  2. Space Requirements: Boiler heat only systems typically require dedicated space for the boiler unit, expansion tank, and associated equipment. This consideration should be taken into account during the planning phase, especially if space is limited in your property.
  3. Limited Cooling Options :Unlike some heating and cooling systems, boiler heat only systems focus solely on providing heat. If you require cooling capabilities during the summer months, additional solutions like separate air conditioning units or heat pumps may be necessary.
  4. Dependency on a Single Heating Source: Boiler heat only systems rely on a single heating source, such as gas, oil, or electricity. This means that a disruption or failure of the fuel source can temporarily interrupt the heating supply. It’s crucial to have backup plans or alternative heating options in place to mitigate such situations.
  5. Potential for System Leaks and Maintenance Needs: Boiler heat only systems involve a network of pipework and components that may be susceptible to leaks or require periodic maintenance. Regular inspections, maintenance, and addressing any leaks promptly are crucial to ensure the system’s optimal performance and longevity.

Key Considerations when Choosing a Boiler Heat Only System

A. Heating Capacity and Size

Assessing the heating capacity and size of the boiler is vital to ensure it can adequately meet your space heating requirements. Factors such as insulation, room sizes, and climate should be considered to determine the appropriate size.

B. Fuel Type Options (Gas, Oil, Electric)

Evaluate the available fuel options in your area and consider their availability, cost, and environmental impact. Each fuel type has its own set of pros and cons, so choose the one that aligns with your preferences and budget.

C. Efficiency Ratings and Energy Savings

Look for boilers with high efficiency ratings, such as an AFUE (Annual Fuel Utilization Efficiency) rating. Higher efficiency boilers can help you save on energy consumption and reduce your heating costs over time.

D. Maintenance and Servicing Requirements

Consider the maintenance and servicing needs of the boiler heat only system. Regular maintenance, such as annual inspections and cleaning, is essential to ensure the system operates efficiently and prolong its lifespan. Additionally, inquire about the availability of qualified technicians in your area for repairs and servicing.

E. Compatibility with Existing Infrastructure

If you have an existing heating system or infrastructure in place, assess whether a boiler heat only system can seamlessly integrate with it. Understanding compatibility issues beforehand can save you time and costs during the installation process.

F. Budget and Cost Factors

Determine your budget for the boiler heat only system, including the installation costs, equipment, and any additional components required. Compare quotes from different suppliers and consider the long-term energy savings to make an informed decision.

G. Environmental Impact and Sustainability

Consider the environmental impact of the boiler heat only system and opt for models that prioritize sustainability. Look for boilers that are energy-efficient, utilize renewable energy sources where possible, and have low carbon emissions.


In conclusion, boiler heat only systems have several advantages, including energy efficiency, even heat distribution, domestic hot water supply, and reduced risk of airborne allergens. However, it’s essential to consider the cons, such as the initial installation cost, space requirements, limited cooling options, dependency on a single heating source, and potential maintenance needs.

When choosing a boiler heat only system, carefully consider factors like heating capacity and size, fuel type options, efficiency ratings, maintenance requirements, compatibility with existing infrastructure, budget, and environmental impact. Consulting with professionals in the heating industry can provide valuable insights and help you make an informed decision.

Ultimately, the suitability of a boiler heat only system depends on your specific needs, preferences, and circumstances. By weighing the pros and cons and considering the key considerations outlined in this blog post, you can determine whether a boiler heat only system is the right choice for your heating requirements.

Remember, investing in a boiler heat only system is a long-term decision, so it’s important to conduct thorough research and consult with professionals to ensure you select the best option for your home or commercial space.

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