GAS BOILERS - Energy Net (2024)

FAQs

How much energy does my gas boiler use? ›

It's hard to give a precise figure to say how much gas your boiler should be using, however you can use the size of your boiler to work out an estimate. A 24 kW boiler will use 24 kW of energy per hour. If your boiler is on for a total of five hours per day, your daily usage should be around 120 kWh.

Modern boilers are designed to run at 90% efficiency (or more), however older boilers could be costing you a pretty penny. Here's some estimated efficiency rates by age: Over 25 years old: 60% efficient. 20 years old: 70% efficient.

Typically the difference between the value of Net combustion efficiency and the value of Gross combustion efficiency for a natural gas fuelled boilers is around 8% with the net value being higher than the gross value. Most boiler manufacturers now quote their boiler efficiencies based on the Net combustion efficiency.

Old boilers are less efficient

While an old boiler might be virtually indestructible, it might become costly to run. In fact, old boilers manufactured over 20 years ago might be just 50 to 60% efficient compared to 90%+ for boilers manufactured in the last 5 years or so.

Instead, it is much more energy-efficient and cheaper to switch your boiler on only when you require warm water or heating with a normal heating system and thermostat, with most people choosing to either use a programmed timer or a smart thermostat that can be controlled from their mobile phone.

The calculation is the kWh of your boiler multiplied by the price of 1kWh of gas, then divided by 100. For example – if your boiler used 30kWh of gas per hour, and your gas cost 10.2p, it would be 30 x 10.3 = 309p, divided by 100 = £3.09 per hour to run your boiler.

Ranked as the number 1 choice of boiler brand in the recent Boiler Guide survey, Worcester Bosch has proven to be a popular, trusted manufacturer amongst home owners. The Greenstar range is consistently rated highly for reliability and quality and the new 4000 model, released in 2021, was quickly awarded as a 'Which?

All new boilers come with an ErP rating sticker, usually on the packaging they come with. To find the model number of your boiler, check the front panel flap. If your boiler is old or missing the sticker, you can check the PCDC database to learn about its efficiency.

On the other hand, a well-maintained furnace can last at least 15 to 20 years. In conclusion, while boilers tend to be more energy-efficient and have a longer lifespan, they are also more expensive initially. Furnaces, while less energy-efficient, are cheaper to install.

Science uses gross. Marketing uses net. When we service boilers we prefer to state the combustion efficiency as a gross efficiency figure since it shows what percentage of the gas you pay for actually produces useful heat.

How to calculate boiler efficiency? ›

Direct efficiency

In order to calculate boiler efficiency by this method, we divide the total energy output of a boiler by total energy input given to the boiler, multiplied by hundred. GCV= Gross calorific value of the fuel.

Net Ratings – The net connected design load that can be supplied with heat by a boiler of given output, allowing for normal system piping losses and pickup from a cold start.

Although your boiler might be functioning as usual, after 10 to 15 years of use, it's time you consider a replacement. The reason for this is that older appliances are usually less efficient than newer, more eco-friendly options.

Reducing the flow temperature down to 60°C on a modern condensing combi boiler will make it run in condensing mode and maximise its operating efficiency. Reduce the flow temperature and monitor how your heating runs over the next couple of days.

But how much electricity do gas boilers consume? Gas boilers use around 100-200 watts, based on daily electrical consumption in average climate conditions. However, it should be noted that your boiler's electricity consumption will vary depending on how frequently you turn on your central heating.

On average, electric boilers use about 10 kilowatt hours of electricity per hour when running. If the boiler is running 10 hours a day to heat your home, that's 100 kWh per day, or 3,000 kWh per month.

To calculate the required fuel flow rate, we divide the total required number of Btus by the Btu rating of our fuel. So we know that at 1000 Btus per standard cubic foot, a boiler needing 10,043,700 Btus per hour will require a fuel flow rate of 10,044 cubic feet of natural gas per hour.

Heating up air requires more energy than heating up water. Due to this fact, furnaces tend to use more fuel over a shorter period of time than boilers. When it comes to heating equipment cost, boilers tend to be pricier, but they can also be a lot more durable than furnaces.

Boilers typically use more energy to start up due to the initial heating requirement, but once at a constant temperature, they use less energy to maintain it.