How do I buy a high efficiency condensing boiler?

Once your home is fully insulated your first step when buying a new boiler should be to get at least three quotes. One of the best ways to find a reliable installer is to ask around - and get a personal recommendation from a trusted friend or relative.

To make sure you're complying with Gas Safety Regulations, you should always use a registered, qualified installer. All work on any gas appliances must be carried out by a Council of Registered Gas Installers CORGI registered installer. We strongly recommend that any oil-fired boilers are fitted by an installer who is registered with one of the following Competent Persons Schemes:

• Association of Plumbing and Heating Contractors Ltd
• Building Engineering Services Competence Accreditation
• NAPIT Registration Ltd
• NICEIC Group Ltd
• Oil Firing Technical Association Ltd
• Institute of Domestic Heating & Environmental Engineers

Competent Persons Schemes were introduced by the government to allow individuals and businesses to self-certify their work as compliant with UK Building Regulations.

Other checks you can make about installers include asking:

• Does the installer have a local office?
• Has he/she been in business locally for several years?
• Are customer references available that you can check?

You can also use our Energy Saving Recommended database to find the boiler that's right for you.

If you're looking for an installer, your local advice centre will be happy to put you in touch with registered professionals in your area. Call 0800 512 012 for free, independent advice.

Your local council may also be able to help with a list of qualified installers. For independent professional advice, you could contact the Heating and Hotwater Industry Council, too.

When your boiler is being installed or serviced, your installer may also need to cleanse and flush your central heating system. There are three ways of doing this: using mains water pressure, pump assisted gravity or mechanically assisted powerflushing.

Powerflushing is the most thorough and effective way to cleanse existing systems - and hot flushing is more effective than cold flushing. But the method your installer uses depends on your make of boiler, as does the type of cleanser. Your installer will always check and stick to the manufacturer's instructions.

If your boiler is installed by a CORGI registered installer or a member of a Competent Persons Scheme (see above for a full list of Schemes for oil boilers), you will get a Building Regulations Compliance Certificate from CORGI or your Competent Persons Scheme member after the work has been completed. Certificates show that work meets Building Regulations standards; CORGI or your Competent Persons Scheme installers will also tell your local authority that you have had a new or replacement boiler fitted.

If your oil boiler is being installed by someone who is not registered with a Competent Persons Scheme, you will need to tell your local authority before the work starts. The local authority is then responsible for checking the work has been carried out to the necessary standards for issuing a completion certificate.

Your installer will also be able to tell you when you need to get your boiler serviced. Any maintenance work on your boiler in years to come should also be carried out by a properly registered professional.

Please remember to keep any boiler-related certificates in a safe place. You'll need them when you sell your home.