Are you wondering how much a new boiler costs in 2021? Are you looking for a boiler replacement but wondering what the price of a new boiler will be? Then look no further. 

We’ve designed this guide to help you to understand the basic costs involved in purchasing different types of gas boilers. We’ll walk you through all the important areas that impact your choices when looking for a new boiler; not just the initial outlay but also maintenance and operating costs.

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Considerations when buying a new boiler

When buying a new Viessmann boiler, you might be tempted to cut corners and save some money. This is false economy. Always use a Gas Safe registered installer for any boiler replacement work, this will ensure your warranty is valid. If you have the option of a longer warranty period, please note that many warranties require an annual service to remain valid.

Carefully consider which brand you purchase as performance and reliability can vary dramatically by brand. While it may seem logical to buy a budget brand and hedge your bets, it could affect you negatively. New boiler costs for budget ranges often reflect the shorter warranty period and lack legacy support for spare parts.

New boiler installation costs

We’ve broken down new boiler installation costs by boiler type, which are:

  • Combi boilers
  • Conventional boilers
  • System boilers

There are pros and cons to buying a new boiler which we’ll take a look at in the next section, to help you decide which boiler is most suitable for your needs. Your best solution is to speak with a Gas Safe registered installer who will be able to guide you. 

Installation engineers work with boilers every day, so when it’s time to upgrade your boiler talk to them about what’s most important to you, for example: Greater energy efficiency and lower running costs, more hot water or the ability to run two hot water taps at the same time.

Combi boiler installation

A combi boiler not only provides heated water for your central heating system but it also gives hot water on demand. If you are replacing like for like then the combination boiler itself is more expensive but fitting costs are lower. Likewise If you are fitting a new heating system to a property then the overall costs to fit a combi boiler would be lower than fitting a conventional boiler.

There are some considerations to make when looking at new combi boiler prices, such as:

  • The size of your property
  • Installation costs
  • Additional variable fitting costs and extras
  • How much hot water you use

Let’s take a look at the available options using a mid-ranged combination boiler as reference.

New combi boiler prices

Size of your property

Estimated new combi boiler cost

Small home

£600 - £1,500

Semi-detached or terraced

£700 - £2,000

Detached home

£900 - £3,500

New boiler installation costs

Type of installation

Estimated boiler installation cost

Replace existing combi


Semi-replace conventional boiler


Install combi in a new location




Estimated cost for boiler ancillaries

Power flush


Pipes (moving)




Chemical flush


Radiator (each)


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Working out the total cost for your new combi boiler

The tables above represent average new boiler costs for a combi boiler. As you can see the prices vary greatly, which is why pricing up a new system can be difficult. In many cases when people price up a new combi boiler they are not aware of the additional costs involved, for example:

Scenario one – Replacing a conventional boiler in a small home

If the new combi boiler costs £700 and the installation costs are £700 then the total installed price will be £1,400. However if your system is old then it may require a powerflush to remove any sludge that has built up. This then increases the cost of a new combination boiler up to £1,900.

Scenario two – Installing a new combi boiler in a detached home

As you’d expect, a larger boiler is more expensive. Then add in the costs of the installation and additional work to reconfigure the pipework. Suddenly the cost jumps up to £3,000, which is significantly higher than the average boiler installation cost.

Conventional boiler costs

A conventional boiler doesn’t heat water on demand like a combi boiler does. Instead, water is preheated and stored in a water cylinder or tank until needed. 

Conventional boilers are typically found in older homes that already have a traditional heating and hot water system. Typically, if you already have one fitted, your conventional boiler replacement should cost between £1,500 and £2,500.

If you are replacing your combi boiler or have no boiler fitted, then the new boiler costs go up. This is because you’ll require a hot water cylinder and cold-water storage tank fitted in your loft. As a rule of thumb, you should expect to pay £2,200 - £3,400 to replace a combi boiler and £2,500 - £3,700 for a new install.

System boiler costs

A third option is to fit a system boiler. These are a hybrid between a combi boiler and a conventional boiler. The system boiler operates like a regular boiler in that it heats and stores hot water in a cylinder but without a cold tank in the loft. 

System boilers are in effect, the modern replacement for regular boilers; where you get to keep your hot water cylinder and therefore have greater hot water comfort and higher flow rates for baths and showers. Because the boiler unit is a single unit, you don’t need to pay for a cold water tank in your loft.

If you already have a boiler fitted then your boiler replacement should cost between £1,600 and £3,000.

If you are replacing your boiler, then the new boiler costs will be less if you chose a system boiler over a conventional boiler. This is because you won’t need to fit a cold-water storage tank in your loft. As a rule of thumb, you should expect to pay £2,000 - £3,500 for a new install.

Saving money with your new boiler

We always advise people to ask for three independent quotes when looking to purchase a boiler. It’s an investment for the future that could payback well with the right purchase decision, and there are a number of factors to consider.

Efficiency saving

Year on year you’ll enjoy not only the comfort of a warm home, but you’ll begin to offset your new boiler costs by saving energy costs. 

If you’re looking to purchase an economy boiler, expect an efficiency of around 89% which will reduce your cost savings by approximately 5%.


Premium products comes with the additional piece of mind that is reflected in the boiler price, with some companies offering up to 10 year warranty when fitted with a partnered installer. If the boiler is at fault, you’ll often pay no excess. For budget boilers warranties are typically 5-7 years and there could be a call out charge. Please note, most boilers require an annual service to maintain warranty validity.

Life expectancy

As you would imagine premium products are made to last. Manufacturers using high quality components such as stainless steel heat exchangers have a higher confidence in the lifetime expectancy of the product, usually resulting in longer manufacturer warranties.

Final thoughts

While the overall cost of a budget boiler may look attractive in comparison to a premium product, do not overlook lifetime value. Many companies now offer 0% finance on your new boiler costs, so you can save £1,000s with a little forward thinking.  

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