A cost guide for Replacing a Gas Boiler at Home



In most homes today, boilers are essential pieces of equipment. It is important to maintain yours properly, because replacement costs can catch you by surprise. Below you’ll find an overview of costs, replacement and service options, cover options and other information related to replacing your boiler at home.


Service Your Boiler


When it’s possible, it is always best to service and maintain the existing boiler, due to the high costs associated with replacement or upgrading to a larger boiler to increase output. Annual services should be utilized to ensure your boiler is working efficiently and safely. Any work done on your boiler should be done by a Gas Safe registered engineer. This should be done before it gets cold enough that you have to turn your central heat on. An engineer will perform a gas safety check to ensure it operates safely, as well as a visual check on some parts of the system, cleaning other parts and a test for leaks. The cost of a boiler service is between £50 and £80. If there are problems and parts need to be replaced, this price will increase. There are many companies that offer to service your boiler when you search online. Just remember to make sure they are a Gas Safe registered engineer.


Do you need Boiler Cover

Tough economic times bring with them difficult decisions, such as whether to pay for boiler breakdown cover. While it might seem out of range, your peace of mind may be worth the added cost. Breakdown cover starts around £5 and can go up to £19 per month, depending on the provider and if you are already a customer of theirs. If you are facing hard times right now, that may seem like a lot of money, but the average cost of a repair was £314 in 2013. If you are shopping for boiler cover, don’t just go with the first one you find. If you look around, you can find affordable options, but make sure you know what’s covered and what would be an additional cost. Companies that offer some type of cover are British Gas, Shield Gas, Scottish Power, 24/7 Home Rescue, and npower. Each offers a couple of different options, so make sure you know what you are comparing. Also, before you purchase boiler cover, check your home owner’s policy. Some of them have an “emergency” clause and if your home is in danger of freezing due to the boiler not working, the repair may not be covered by policy. 



However, before you purchase any breakdown cover always check the small print with the policy because while the call out costs are covered in your policy, you may only be entitled to half an hour labour and not including replacement parts costs, and this is usually how these bigger companies make up their profits once they are “in the door”.



Also it would be wise to weigh up the age of the boiler, previous problems (both recent and older) with the boiler and the costs you would have to outlay every year for cover against paying for a new boiler with a long warranty or just looking after your boiler (having serviced) and central heating system with cleaners and inhibitors and if you can afford it having a magnetic filter/cleaner installed to protect your system and boiler from the dreaded “sludge”.


Before Purchasing a New Boiler

Boilers can sometimes have problems that can be fixed by engineers that are Gas Safe registered, so that you don’t have to spend an excess of money to purchase a new one. Here are some things to try before you replace your existing boiler.


  • Having your boiler serviced can fix a lot of problems before they get out of hand. Also, read the manual that came with your boiler, as it may have some maintenance tips in it as well. 
  • Insulate the walls, windows and loft of your home. 
  • Draught-proof your home. Draughts can cause you to lose heat to the outside if there are gaps, or due to the cooling effect of winds beating on your home. The Energy Saving Trust says that you can save up to £50, or 10%, on your heating bill by draught proofing. 
  • Buy new controls for the thermostat, radiator thermostat, a new timer and possibly new radiators. All of these items could help you save money on your heating bill. 
  • Make sure your gas company is charging you the lowest price possible for gas. Sometimes, there is nothing wrong with your equipment, but the rates may have increased.



How do you know when it's time to replace your Boiler

If you have tried out the suggestions for improving your efficiency with little or no success, it might be a sign that it’s finally time to replace your boiler. While an older boiler operates with less efficiency than a newer one, don’t just replace it based on its age. Many older models are made with more quality materials and with less moving parts to malfunction. Newer boilers have electronics that need expensive repair work averaging around 5 years into their life span. When you have had several problems with your boiler, the engineer might say that it cannot be fixed and therefore needs to be replaced. If you want more flexibility in your controls (ie. Thermostat, timer, etc.) and adding new controls didn’t help, you might want to consider purchasing a new one with more options.


  • Older systems have a “dry cycle” where it continues to blow heat into the home even when it is up to the correct temperature.
  • Older boilers also have a pilot light at the bottom that stays lit continuously and wastes gas. 
  • If you have a G-rated boiler and replace it with an A-rated boiler with a full set of controls, you can save up to £215 on your heating bill and 940kg of carbon monoxide a year. To check the energy rating on your boiler, visit 
  • A new boiler will add value to a home buyer if you are looking to sell your home. 
  • If your boiler sits on the floor, more than likely, it’s an older model and likely not as efficient.

Types and Cost of Boiler

There are many different types of boiler systems and the cost varies widely depending on what you require for your home. They start at £500 and go up to £2,500.



Combination Boilers

The combi boiler is a good solution for a home with a small to medium family that needs hot water in different locations at the same time. If your current boiler is accompanied by a hot water cylinder and you don’t need all that stored hot water then upgrading to a combi boiler which will give you hot water as and when you need it, will probably help keep the bills down a bit and give you back some space from the airing cupboard. Prices for a system conversion to a combi boiler vary depending on size and make and model of the boiler but can start from £1700 ranging to £3500 for the bigger nation companies like British gas



Gravity fed Boilers

A cold water tank is located in a place like a loft and has the potential to burst and cause water damage. However, it is the more economical option if you have a hot water cylinder with a tank fed “heat only” boiler and if there is a lot of use for hot water in a home, replacing one like-for-like is a logical option and they average around £1500-£2000.



High pressure (unvented system)

For a new installation, high pressure systems are used very often. It is the modern day way of installing a central heating and hot water system, by having a “system boiler” with an unvented hot water tank which is fed from the main cold water supply, so therefore giving you high pressure hot water that can give you an excellent flow rate of hot water at different outlets in the house at the same time. Only a high spec and high KW combi boiler can match the flow rates from an unvented system. So if your system boiler is getting old or having multiple problems installing a like-for-like replacement is the best option for a high pressure system. Costs can vary but a straight system boiler swap will range from £1500-£2500 depending variables.



Solar Water Heater

A solar water heater has a higher upfront cost, but the trade off is savings on heating bills, as well as a subsidy through the Renewable Heating Initiative (RHI). It pays you 19.51p per kWh of heat produced for 7 years. Excess energy can be rerouted to the electricity grid or the water heater. The costs range from £3,000 to £5,000.



Boiler Manufacturers

Alpha Heating Innovations
• Ariston
• Baxi
• Biasi 
• Buderus
• Chaffoteaux & Maury
• Glow worm
• Heat Line
• Ideal
• Keston
• Potterton
• Ravenheat
• Saunier Duval
• Vaillant
• Viessman 
• Vokera
• Worchester Bosch




After you have decided on what type of boiler you need, the next step is to shop around for a company to install your new unit. You should make sure that they are registered with Gas Safe so you can be confident that the work will be done correctly and professionally, the engineer will have good customer service skills and they should dispose of the rubbish themselves. You also have to decide if you want to work with a smaller local company or a large national one. Local companies have smaller overhead, so they don’t pass those costs along to the customers. They also don’t have the budget to do a lot of marketing, so they depend on word of mouth advertising by happy customers. Also check that the company has liability insurance and gives a guarantee of their work for a minimum of 6 months, which should cover the basic things like the pipework not leaking and condensate pipes not getting frozen. The large national companies have large marketing budgets, but they also have larger overhead costs, so they are looking to recoup those costs by passing them along to customers. When comparing quotations from installers, ask for an itemised list of what is included so you can make sure you are comparing like for like. Some companies may offer services that could save you money on repair costs in the long run. Engineer labour will cost between £500 and £1000. Other expenses will incur if you are upgrading your boiler, replacing radiators or other parts, of your system.



FinancingThere are several different schemes that are available to help cover part of the cost of buying a new boiler. Some utility companies (such as British Gas), allow you to break up the cost over the boiler over several years, so you can make payments to them. Other options for assistance can be found below. 

• The Energy Company Obligation (ECO) that is required to assist low income homes with boiler and insulation purchases.
• A child tax credit for homes with income less than £16,010. 
• Age and disability assistance.

There are two websites you can check to see if you qualify for any of the grants that are available. Check out and




Return-on-investment depends on a number of variables, such as how old and inefficient your old boiler is and how much more effective the new boiler model is. The cost savings would be spread out over a number of years, but when 50-60% of your household expenses are spent on heating costs, it makes sense to ensure the money you are spending is being used correctly.

 If you opted for a new boiler with 90% efficiency costing £1800, here's how much you could expect to save on a typical gas bill and how long it would take to pay for itself:

Efficiency of your old boiler Annual saving on your gas bill in % Annual saving on your gas bill in £ How long it will take for your boiler to pay for itself

60% 33% £237 7.6 years65% 28% £201 9 years70% 22% £158 11.4 years75% 17% £122 14.8 years80% 11% £79 22.8 years

The calculations above are based on a home with gas-powered central heating, using an average 17252 kWh gas p/a at a cost of £666 p/a. (


Plumbing & Heating Services in Rutland, Stamford, Peterborough