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How Much Gas Does A Boiler Use Per Hour?

If you have had a spike in your energy bills, or you are considering other options from a gas boiler, then one of the main things you will need to know as a homeowner is how much gas your gas boiler typically uses. There are a few factors that determine how much is used, but a good way of telling is simply by looking at the Kwh of your boiler and its efficiency rating.

A 35-kilowatt boiler (which is an average household boiler in the UK) consumes 35 kilowatt-hours worth of gas. If your 35kW boiler runs for five hours a day, your daily consumption should be roughly 175 kWh.

Looking kWh to work out your gas usage

The best way to measure gas consumption is to use kilowatt-hours (kWh), a standard unit of measurement. A typical low-consuming household is around 8,000kWh, 12,000kWh for moderate consumption, and 17,000kWh for heavy-consuming homes per year. 

So that would put the average monthly gas usage to around 1,000 kWh. A kWh represents the energy required to run a 1,000-watt appliance for one hour, so 1 KW is 1,000-watts. However, your residential gas use typically includes gas boilers and cooking, and other purposes. Which means that when you are trying to calculate the exact gas usage of your boiler, it is not always clear where that gas had been consumed.

Calculating your average monthly energy bill

Calculating your average monthly energy bill can be difficult due to various factors such as different consumption habits, where you live, your usage, and even how you pay for your energy. 

If your fixed-rate agreement has expired or you have just transferred home, you will be subject to a basic variable rate tariff (SVR). The table below illustrates the average energy bill for customers on a basic tariff.

The amount of gas boiler fuel consumed is influenced by factors, such as the type of boiler, the age and condition of the boiler, the efficiency rating, and how large your home is in relation to the boiler. Therefore, it’s best to calculate the amount of energy consumed to heat your home in kWhs.

How much does it cost to run gas central heating per hour UK?

If you use mains gas, you’ll pay roughly 2.4p per kilowatt-hour. This means that if you have a 35 kW boiler, it will cost you around £0.84 to run it for an hour. However, if you use LPG, it can be a little more expensive. The cost of running an LPG boiler is around 7.6p per kilowatt-hour. So, you have to pay roughly £2.66 per hour to run a 35 kW LPG combi boiler.

Why is my boiler using so much gas?

If your boiler uses more gas than it should, check with your provider to ensure that their prices haven’t increased. If they haven’t, here are a few more reasons why you might be consuming more.

1. Using an older boiler – After a few years of service, the boiler’s efficiency degrades. New gas boilers can be up to 96% efficient but typically sit around 85-92%. However, boilers over ten years old can lose up to 30% of their efficiency. Which is typically why we suggest getting a new boiler fitted after 10 years. 


This means that if you have a 35 kWh boiler which is 85% efficient, you will need to use 40.25 kW to get 35 kw energy usage for your property as the other 15% (5.25) is lost. Moreover, to calculate the cost of running an older boiler that is 30% less efficient. This would result in an additional 10.5 kWh of gas consumption for your old boiler, for a total of 45.5 kWh. 


2. Malfunctioning programmer or thermostat – Your boiler should stay off when it has already reached its pre-programmed temperature. A faulty thermostat or programmer may cause your boiler to operate indefinitely, burning more gas. 


Check to see if you have the proper timings and temperatures set. Observe your boiler for any indications that it turns on even though the thermostat or programmer is turned off. To resolve the issue, you may need to contact a boiler engineer


3. Broken motorized valve – The flow of hot water from the boiler into a cylinder or the radiators is controlled by a motorized valve. The valve opens to allow water hot water to flow when the boiler is turned on and then closes to halt the flow when it’s off. 


However, this valve could fail or become jammed. This will cause your radiators to continue to heat up even when they don’t need to. Check to see if the manufacturer’s warranty is still in effect. Ensure that your valve is inspected and changed by qualified technicians.

How much gas does a pilot light use?

Boilers under 15 years old use electronic ignition and do not have pilot lights. On the other hand, older boilers feature a pilot light that fires continuously and consumes roughly 1,500kWh or more per year. 

A pilot light is used to start the main burner when the boiler is turned on, it remains lit. If your boiler has a pilot light, consider upgrading to a more energy-efficient one. This could save you money on the gas used to power a pilot light.

How many hours a day should heating be on?

The length of time your heater runs will be determined by how well your home is insulated. In the winter, centrally heated homes in the UK are heated for approximately 8.7  hours a day. However, the majority of homeowners start heating their home daily from October to March or April. Therefore, the heating season is expected to last approximately 5.6 months.

Yearly maintenance is important

Keeping your boiler in good working order might help you save money on gas. It can also help to avoid potential problems that can reduce energy efficiency and lead to premature failures. Make sure that your gas boilers are inspected by certified gas engineers at least once a year.