Frequently Asked Questions
Gas & OIl


What is gas central heating and how does it work?

Most of us here in the UK use a mains gas central heating system, sometimes called a ‘wet system’, to keep ourselves and our homes warm and comfortable.

This type of system works by using a gas boiler to provide heat in your home through radiators and hot water through taps. There are different kinds of gas boilers for central heating, and you can find out more about these by taking a look at Gas Safe's boiler quide:

At the centre of a ‘wet central heating system’, a boiler burns gas which heats the water feeding a network of pipes connected to your home’s radiators and a hot water tank.

Gas central heating isn’t the only option for homes in the UK. Households which aren’t connected to the mains natural gas network might use electric central heating, LPG or oil central heating systems.

What are the pros and cons of gas fuelled central heating?

If you’re thinking of getting gas central heating installed in your home, then you’ll want to consider the advantages and disadvantages first.


Modern condensing boilers are extremely efficient

It is relatively simple to replace a standard gas boiler with a high efficiency condensing boiler. Mains natural gas systems are piped directly into your home; there’s no need to store it


Gas central heating systems often have a higher upfront cost that other systems, such as electric but lower running costs long term.

It may be expensive to get your home connected to the gas network if it’s not already

Gas central heating installation 

If you’re having a gas central heating system installed in your home, this needs to be done by a competent Gas Safe registered engineer.

It’s the law that gas engineers to be registered with Gas Safe Register. This shows they’ve undertaken at least one industry recognised & accredited competencies to work with gas. However, not all engineers are qualified or competent to do all types of gas work; you’ll need to check their Gas Safe ID card to make sure they have the right qualifications to work on a gas central heating system.

If you don’t already have a boiler your central heating installer will be able to advise you on the best type of boiler to use in your home. This will ensure it can meet the heating demands put on it by the size of your home.

Your gas boiler is the central component in your gas central heating system, and as a heat-producing appliance, it needs to be approved as safe and appropriate for use under the Building Regulations.

Once your Gas Safe registered engineer has installed your central heating system, they will need to let the relevant local authority know within 30 days, so that a Building Regulations Compliance Certificate can be issued.

If you’re a homeowner, it’s up to you to check your boiler has been notified by your engineer.

Gas central heating servicing and maintenance

An unsafe or improperly maintained gas appliance could put you and your household at risk, which is why it’s important that any gas appliance in your home is correctly maintained by a Gas Safe registered engineer.

This includes the gas appliances in your gas central heating system. Regular servicing and maintenance of your gas central heating system by a competent central heating engineer will ensure your appliances stay in good working order and are safe for continued use in your home.

What does a central heating service involve?

Regular servicing of your gas central heating system will ensure it stays in good shape and is safe to use. Unless otherwise stated in the manufacturer’s instructions, you should ensure your gas appliances have an annual service completed by a Gas Safe registered engineer.

As the main heat-producing gas appliance within your central heating system, safety checks on your gas boiler - in line with the manufacturer’s instructions - will form a crucial part of your central heating systems ongoing performance. You can find out more about boiler servicing and maintenance within our boiler guide.

After your engineer has carried out a service on your boiler you should be provided with a service report, or Gas Safety Record, detailing all the checks that were made and any work carried out.

During your gas central heating service your engineer may check your radiators and pipework to ensure this is in good working order. If you would like this done, please ensure you let your engineer know.

Gas central heating system maintenance tips

Even with proper maintenance on your part, the best way to keep your gas central heating system working safely and efficiently is by using a Gas Safe registered heating engineer to complete regular gas safety checks and servicing.

While it’s important to have your gas central heating system regularly serviced by a Gas Safe registered engineer, there are a few steps you can take to keep your system working safely and efficiently in the meantime:

Check the central heating system water pressure where applicable - Boilers can lose system pressure as they age. Check the pressure gauge and top it up if it’s too low

Bleed excess air from your radiators - You can tell if your radiators need bleeding if they’re colder at the top than the bottom, meaning excess air is trapped in the system, putting extra strain on your boiler

Lag the pipes - When it gets very cold your boiler’s external condensate pipe can freeze and your boiler will cut out. You can prevent this by asking a Gas Safe engineer to insulate your condensate pipe

Signs of an unsafe gas central heating system

A problem with your gas central heating system has real potential to put you and your household at risk.

If you can smell gas, can see visible scorching, sooting or black marks, or a floppy yellow pilot light on your boiler, or if you or anyone in your household has been feeling unwell and experiencing headaches, nausea or dizziness, it’s crucial to act quickly.

Get out of the property, turn the gas off if safe to do so and contact your gas emergency service. You could find the numbers to call on our What to do in a gas emergency web page.

Carbon monoxide (CO) is a highly poisonous gas produced by the incomplete burning of natural gas or liquefied petroleum gas (LPG). This can happen when a gas appliance has been incorrectly fitted, badly repaired or poorly maintained.

Further Information

For further information please go to the Gas Safe website by clicking on the link below


What is heating oil?

Heating Oil also known as kerosene, 28 second burning oil and boiler juice is a fuel to heat households not connected to the mains gas network. It is being used for both heating and cooking needs by one million homes in Great Britain.

Where can i purchase heating oil?

These are just a few suppliers in the area:

Boiler Juice                         01480 775454 

Badger Fuels                                      01473 558854 

Goff Heating Oil                        01953 713555 

Blackwater Fuels                    01621 868868

Heating Oil Today                               01245 830425

How safe is heating oil?

Heating oil is now considered to be as clean as any other fuel. A properly maintained boiler should not produce any visible smoke or toxic fumes.

Carbon monoxide can be produced by all fossil fuels and is caused by the incomplete combustion of the oil. If your boiler is producing black smoke or soot, this would suggest that it is not functioning properly, and the risk of carbon monoxide exists. This is a good reason to have your oil heating system properly maintained. Fitting a carbon monoxide detector is always advisable when using fossil fuels.

Although oil is flammable, it is not likely to explode like natural gas. Before heating oil can ignite, it must be vapourised at a temperature of 140 degrees. It cannot burn in its liquid state.

Heating oil is often referred to as Kerosene. However, there are two grades of oil in the United Kingdom. There is Kerosene BS 2869 Class C2, which is a heavier oil distributed in bulk by our tankers and used as a domestic heating oil. The BS 2869 C1 is a premium Kerosene generally used for camping, gardening and general needs, such as, in stoves, wick heaters and lanterns

Do I need to maintain my oil tank and boiler?

Your boiler and oil tank do need to be properly maintained.

OFTEC recommend servicing both your boiler and your oil tank annually. Your boiler will need regular cleaning and it also contains parts that will need replacing from time to time. An oil heating system can become easily contaminated, including the oil tank.

How do I know how big my oil tank is?

If you have a metal tank measure the length, width and height of your metal tank in feet and then multiply these 3 figures together. Take the total number and multiply by 6.25. This will give you the cubic capacity in gallons. For litres, divide your answer by 4.54.

If you have a plastic tank, the capacity will be detailed on the tank.

What do I do if I have an oil leak or oil spill?

Please follow the link below for advise on what to do in the event of a spill or leak or consult OFTEC's website:

What causes oil boilers to lock out? 

This could be a result of no oil, a leak in the oil pipe or contaminated oil.

Contamination can be caused by water in the tank, from condensation, a cover not be replaced or a crack in the tank. Sludge can also occur in the tank due the growth of micro-organisms.  

If a tank becomes contaminated, the oil will need to be removed, the tank and oil cleaned and the oil replaced to the tank.

 Some benefits of oil central heating

Safety – although oil is flammable, it’s not explosive like gas
Efficiency – heating oil burns at a higher temperature than natural gas and delivers more heat than other heating sources
Ideal for remote locations – if you aren’t close to a natural gas supply line, you can still arrange deliveries of heating oil
Lower up-front costs – boilers that run on oil tend to be cheaper than those that burn gas.

Further Information

For further information please go to the OFTEC website by clicking on the link below