An old failing boiler often means a future replacement is in the cards. The moment you really think about getting a new boiler, of course, you start to think of two huge questions: “How to use a boiler calculator?” and “How much does a new boiler cost?”
With so many kinds of boilers and installation options, the prices can vary. This is where the boiler calculator will be able to come in handy and help you make an estimate of the total cost. It considers the size of your home, the type of boiler, and the installation complexity.
The blog will take you through everything you need to know about boiler calculators – from the right size choice of the boiler to what basically influences the costs of the boilers.
How Does a Boiler Calculator Work?
The boiler calculator can save you quite a lot of time and frustration. It will very rapidly narrow down options for you and provide you with an estimate that’s pretty realistic, basing its predictions on your situation. Most boiler calculators ask a series of questions about both your home and your heating needs.
For Example
A house that has more bedrooms and bathrooms may require a much larger boiler system than what an apartment or a bungalow would need. The tool follows up on the assumption of your response to this question: what type of dwelling do you live in – flat, house, or semi-detached? How many beds and bathrooms?
Some details of your existing heating system and the number of radiators will be enquired from you. What type of a boiler is fitted at your house: a combi or a conventional one? Has the boiler been connected to a gas line or do you use some alternative fuel, like oil or LPG?
This boiler calculator will give you a rough price once you enter these details not only about the boiler but also for its installation. The calculator is just a handy guide to let you budget accordingly for the new boiler installation without surprise blows.
Boiler Calculator: Factors Affecting the Boiler Costs
Several factors influence the cost of a new boiler and fitting. Here’s a breakdown of the main elements:
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1. Boilers Types
Combi Boilers
Combi or combination boilers heat the water directly from the mains. So, you do not require a cylinder or a tank to store water. Because of their small size and efficiency, these combi systems can prove to be the most attractive option when space is limited in one’s home.
- Best for: Smaller homes, single bathroom.
- Power output range: Generally 24-40 kW.
- Price: £1,500 – £4,500 (inclusive of installation cost).
System Boilers
System boilers depend on a separate cylinder to hold the hot water, but most of the major components are enclosed within the case of the boiler. Therefore, not as much extra hardware is involved, and the installation can be a bit easier.
- Best for: Medium to large homes with higher hot water demand.
- Power range: 15-40 kW.
- Cost: £1,580 – £5,000 (inclusive of installation cost).
Conventional Boilers
These require a cold water storage tank and a hot water cylinder. These are less space-efficient but can service homes with larger hot water requirements.
- Best for: Large homes or old properties with outdated central heating systems.
- Power range: 15-40 kW.
- Cost: £1,600 – £5,000 (installation included).
Here is a quick overview:
Boiler Type | Cost (excl. Installation) | Cost (incl. Installation) | Average Cost (incl. Installation) |
Combi | £500 – £3,000 | £1,500 – £4,500 | £3,000 |
System | £580 – £3,500 | £1,580 – £5,000 | £3,290 |
Conventional | £600 – £3,500 | £1,600 – £5,000 | £3,050 |
2. Installation Complexity of Boilers
Installation of the boiler can range anywhere between £500 and £1,500. It all depends on the amount of work involved. Among the factors that would involve installation costs are:
- Pipework: If your new boiler requires larger pipes or the current setup is outdated, this can add to the overall cost.
- Positioning of the new boiler: If the new boiler is to be installed in some other location, say shifting it from the kitchen and placing it in the loft, the labour cost will come out to be higher.
- Additional components: Other additional parts, which can be a flue pipe, thermostatic radiator valves, or a magnetic filter, are needed and also add to the cost.
Additional Costs | Price Range |
System Powerflush | £50 – £150 |
Magnetic Filter | £100 – £150 |
Thermostatic Heat Controls | £70 – £650 |
New Boiler Flue Pipe | £50 – £150 |
3. What Size Boiler (kW) Do I Need? (Boiler KW Calculator)
Here is the approximate guide to boiler size by the number of radiators in your home:
Number of Radiators | Combi Boiler Size (kW) | System/Conventional Boiler Size (kW) |
Up to 10 | 24–27 kW | 12–15 kW |
10–15 | 28–34 kW | 18–24 kW |
15–20 | 32–40 kW | 30–40 kW |
The size of your boiler is measured in kilowatts (kW). The rating in kW is a measure of the power and ability of a boiler to meet heating and hot water needs. It reflects its capacity to meet your heating requirements. A boiler that is too small simply will not heat your home properly, whereas one that is too large will waste lots of energy and inflate your bills.
Following is a rundown of some key things to consider:
- Property size: Larger houses require bigger boilers, for instance, to maintain proper heating.
- Number of radiators: The more radiators, the more kW is needed.
- Number of bathrooms: Houses with more bathrooms require a high-capacity boiler.
- Insulation and heat loss: The poorer the insulation, the higher the kW output needed to retain heat.
- Hot water demand: For a house with heavy usage, it is important that the boiler can meet such a demand. Therefore, either a system or a conventional boiler will do the job.
4. Power Input, Output, and Efficiency
When choosing a boiler, two of the most common figures quoted are power input and power output. Power input is the amount of energy required by the boiler, while power output indicates how much of that energy is given out as usable heat.
The difference between these two figures reflects the boiler efficiency. Condensing boilers of recent origin have an efficiency of about 90-94%, which means there will be hardly any losses resulting from operation.
5. Boiler Brand
Not all boilers are created equal, each commanding a differently weighted price tag and level of reliability. Some of the top boiler brands in the UK, such as Worcester Bosch, Vaillant, and Ideal, are well-reputed but rather high-reaching in price.
Boiler Cost Calculator: Estimating the Average Boiler Cost
Here’s a breakdown of the average boiler costs based on property types:
Property Type | Bathrooms | Cost |
Terraced House | 1 | £2,460 |
2 | £2,650 | |
3+ | £3,000 | |
Semi-detached | 1 | £2,548 |
2 | £2,770 | |
3+ | £3,300 | |
Detached House | 1 | £2,682 |
2 | £2,881 | |
3+ | £3,500 | |
Flat/Apartment | 1 | £2,376 |
2 | £2,520 | |
Bungalow | 1 | £2,690 |
2 | £2,833 |
How to Save Money on Your Boiler Installation
Boilers can be quite expensive to install, but here are ways of saving money:
- Compare Quotes: Get quotes from more than one installer to ensure the best price. Installation costs may differ drastically among companies.
- Check for Grants: The ECO4 scheme provides free boiler replacement for low-income families or similar cases. Search if there’s already a grant you may qualify for that can cover partial or full installation costs.
Final Thoughts – Let the Experts Help!
While online boiler calculators can give you a rough estimate of boiler costs and size, it’s always best to leave the final decision to the professionals themselves. In this case, for the most accurate advice and installation, seek out a Gas Safe registered engineer.
Are you ready to upgrade new boiler?
Invest now in a new, efficient boiler with the ECO4 Scheme. Contact a trusted installer today for free modern heating solutions to keep your home warm and energy bills low.
Frequently Asked Question
To estimate the size of your boiler, that is done by counting how many radiators are in your house. As a general rule of thumb with combi boilers:
- Up to 10 radiators: 24–27 kW.
- 10 to 15 radiators: 28–34 kW
The larger the house, with more radiators, the bigger the boiler will need to be.
A rough estimate of the size can be made by thinking of around 1.5 kW per radiator. Additionally, consider the demand for hot water, particularly with combi boilers, depending on the number of bathrooms and typical water usage.
For smaller 1-2-bedroom houses, including flats and apartments, the approximate best sizing is a combi boiler with a size of 30kW. This size would provide decent heat and hot water in smaller areas.
Boiler size is the heating capacity of the boiler. It is measured in kilowatts (kW). This explains the quantity of heat the boiler will be able to generate to warm your home and supply hot water.
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