Gas Consumption and Heating Savings
Gas Consumption and How to Save on Heating – Practical Advice
For most households with gas heating, the gas bill is the largest recurring item in the budget during the heating season. The good news is that even a household with no plans to replace the boiler or insulate the house can influence its consumption. Part of the savings can be achieved simply – with correct control settings, regular maintenance, and a few habits that cost nothing. In this article we'll go step by step through what most affects gas consumption for heating, how weather compensation control works, why night setback pays off, what impact maintenance and bleeding the system have, and finally we'll sum up practical tips that we can recommend from our own experience with thousands of customers.
Maintenance factors covered in the article below.
What Most Affects Gas Consumption for Heating
Gas consumption isn't the result of a single factor, but the sum of several influences that multiply with each other. Let's go through them one by one.
Insulation of the House
Heat loss through the outer walls, roof, and windows is, in the long run, the strongest factor affecting consumption. An uninsulated or only partially insulated house loses heat significantly faster than one with quality insulation, so the boiler has to run longer and at higher output to maintain the same indoor temperature. Insulation is an investment with a long payback period that usually can't be solved "over a weekend" – which is why in this article we focus instead on measures a household can control immediately, without any construction work.
Boiler Output and Type
An oversized boiler (unnecessarily high output relative to the house's needs) switches on and off more often (so-called cycling), which reduces its efficiency and increases wear. An undersized boiler, on the other hand, runs continuously at maximum and can't keep up with heating the house on freezing days. Compared to an older, conventional (atmospheric) type, a condensing boiler also makes use of heat from the flue gases that would otherwise escape through the chimney – which is why replacing an old boiler with a condensing one typically shows a noticeable drop in consumption. If you're looking into choosing a boiler or its output in more detail, we cover that in separate articles below, in the Related Topics section.
Type of Heat Emitters – Underfloor Heating vs. Radiators
Underfloor heating works with a lower heating water temperature (typically around 30 – 40 °C) than conventional radiators (commonly 50 – 70 °C). A lower water temperature means the condensing boiler can operate in condensing mode longer and more efficiently, which directly shows up in gas consumption. This doesn't mean radiators are "bad" – they simply require more careful setup of the heating curve and control, so the water isn't unnecessarily heated above what the room actually needs.
Correct Control Settings
This is the point that's most often underestimated – and yet it's one of the cheapest ways to save. A boiler fixed at a high heating water temperature regardless of the weather outside burns gas needlessly even on days when much milder heating would be enough. We'll explain how to solve this in the next chapter.
Tightness of Windows and Doors
Leaking windows and doors cause uncontrolled cold air infiltration into the interior, which the boiler constantly has to heat back up. Simply checking the seals, or replacing worn rubber window seals, can reduce heat loss without a large investment.
Weather Compensation Control as the Main Savings Tool
If we had to pick a single measure with the best ratio of "savings vs. effort and cost," it would be weather compensation control. The principle is simple: instead of setting the boiler to one fixed heating water temperature and changing it manually by feel, a weather compensation controller automatically adapts the water temperature in the system to the current outdoor temperature.
When it's freezing outside, the system delivers a higher water temperature to keep the house at a comfortable temperature. When it's milder outside, for example in spring or autumn, the boiler automatically lowers the heating water temperature – tailored exactly to the current need, no more. This eliminates the common mistake of manual setting, where the homeowner sets the boiler "for winter" once at the start of the season and never changes it again, causing the house to overheat unnecessarily on milder days and burn more gas than needed.
When switching from manual settings to good-quality weather compensation control, in practice people commonly talk about an approximate saving on the order of a few percent up to the low tens of percent (a range of roughly 10 – 15% is typically cited) compared to a household that has no such control or doesn't use it correctly. Take these figures as a rough guide, not a guarantee – actual savings depend on the specific house, existing habits, and settings, so in your case it may be lower or higher.
For weather compensation control to work, the boiler needs to know two things: the current outdoor temperature, and what temperature you want indoors. Two components are commonly used together for this:
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Protherm – Outdoor temperature sensor (wired) for boilers with an eBus bus – this outdoor sensor is the basic building block of weather compensation control. It measures the real outdoor air temperature and sends it to the boiler, which uses it to calculate the required heating water temperature on its own. Without an outdoor sensor, weather compensation doesn't work – the boiler would have nothing to react to. Price from €33.54. |
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Vaillant VRT 50 – a room-based weather-compensating thermostat that complements the outdoor sensor with information from indoors and allows you to comfortably set the desired room temperature and time program right from the living room. This "outdoor sensor + room thermostat" combination is the typical way weather compensation control is implemented in practice – and how the control is set up is actually one of the biggest factors affecting the resulting consumption. Price from €71.64. |
It's worth adding that not every thermostat is automatically "weather-compensating" – some models work only as a simple room thermostat that switches heating on and off based on the measured room temperature, with no link to the outdoor weather. If you want to actually take advantage of the weather compensation principle, both the boiler and the control need to be designed for it and correctly connected (often via a bus such as eBus, OpenTherm, and similar) – if you're not sure about compatibility with your boiler, we recommend consulting directly with our customer service or your installation company.
Lowering the Temperature at Night and When Away – Setback
The second very effective yet cheap tool is so-called setback – temporarily lowering the desired temperature at times when full comfort heat isn't needed. Typical situations are night (you don't need the same temperature while sleeping as during the day) or a longer absence at work.
Most modern room and weather-compensating thermostats offer a weekly program where you can set several time blocks with different desired temperatures for each day of the week – for example a lower temperature during the night and working hours, and a higher one in the morning and evening, when the family is at home. There's no need to worry that the house will "cool down and be more expensive to reheat" – with a normal, moderate setback (typically 2 – 3 °C, not switching the heating off entirely), reheating back to a comfortable temperature is generally more efficient than keeping the full temperature non-stop, since the house loses less heat to its surroundings throughout the setback period.
Practical tip: set the setback gradually and moderately. Too steep a temperature drop at night can, in older or less well-insulated houses, mean the boiler has to reheat the house intensely and for a long time in the morning, which reduces part of the expected savings. It's best to try a few settings and see what works best for your house and family.
System Maintenance and Cleanliness
Even the most modern condensing boiler with correctly set controls loses efficiency if the heating system is dirty. Over the years, deposits naturally form in the heating circuit (water, pipes, heat exchanger, radiators) – mainly limescale and so-called magnetite (black sludge produced by corrosion of the system's steel parts).
Why a Dirty Heat Exchanger and Radiators Lose Efficiency
Deposits act as an insulating layer. Even a relatively thin layer of limescale or sludge on the walls of the heat exchanger significantly worsens the heat transfer from the burning gas (or from the heated water) into the heating circuit. The result is that the boiler has to burn more gas to achieve the same heating effect as with a clean heat exchanger. The same principle applies to radiators – a clogged radiator releases heat into the room more slowly and less efficiently.
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NANO HOT 3/4" - 1" 500 mcr brass water filter for heating systems – a brass filter that catches mechanical dirt and deposits before they reach the boiler's heat exchanger and the radiators. Keeping the heating circuit clean is one of those measures that's easily underestimated in practice, yet a heat exchanger free of deposits transfers heat more efficiently, which directly translates into lower gas consumption. Price from €65.50. |
A filter on the return or supply branch of the heating circuit is one of the cheapest safeguards for protecting the boiler's heat exchanger against deposits that would otherwise gradually reduce its efficiency. We recommend combining it with regular inspection and, if needed, chemical cleaning of the system (especially with older piping, where a larger amount of sludge has accumulated over the years).
Bleeding the System
Air that accumulates in the heating circuit over time – typically in the upper part of radiators – is another factor affecting consumption that's easy to overlook but very real. An air pocket in a radiator blocks the circulation of hot water in that part of the radiator, so it doesn't heat evenly across its whole surface and is typically cold at the top, warm at the bottom. As a result, the room heats up more slowly and less efficiently, which the system "compensates for" by running the boiler longer.
Bleeding radiators is a simple task that most households can handle themselves with a bleed key – just slightly open the bleed valve at the top of the radiator until air stops escaping and water starts to flow. We recommend checking this at least once at the start of the heating season, or any time you notice a radiator heating unevenly or making noise (bubbling, knocking in the pipes).
More Practical Savings Tips
Room-by-Room Thermostatic Heads
Thermostatic radiator heads let you set a different temperature in each room separately – there's no reason to heat a bedroom or storage room to the same temperature as the living room. The same principle applies here as with weather compensation: heat exactly as much as is actually needed, not more "just to be safe." A programmable head can also lower the temperature in a specific room on its own schedule, independently of the rest of the household – for example in a child's room during the day, while the child is at kindergarten.
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Elektrobock EMF-1 – a programmable thermostatic radiator head with its own weekly program, simply screwed onto the existing radiator valve with no need to modify the piping. Price from €20.06. |
Closing Blinds and Shutters at Night
Windows are the weakest link in the building envelope in terms of heat loss. Closed blinds, shutters, or thick curtains at night create an additional layer of air that reduces heat loss through the glass – a simple, free measure.
Not Covering Radiators with Furniture and Curtains
A radiator covered by a sofa, long curtains, or a decorative cover can't efficiently release heat into the room through air circulation. Heat builds up behind the obstruction instead of warming the living space, and as a result the thermostat doesn't "see" the room's real temperature correctly.
Regular Boiler Servicing
An annual boiler service inspection (checking the burner, heat exchanger, seals, combustion settings) isn't just a matter of safety and warranty – it's also about maintaining the boiler's stated efficiency throughout its whole service life. Neglected servicing can lead to a gradual rise in consumption that a household may not even notice until a higher bill arrives.
Smart/WiFi Control as an Add-on to Weather Compensation
A classic room thermostat or thermostatic head works reliably even without internet access, but a smart/WiFi version adds two practically useful things: remote control from your phone (for example, turning on the heating while still on the way home from a weekend house) and a clear consumption history right in the app, which makes it easier to quickly spot that something is "eating" more gas than usual – for example a forgotten deep setback or a leaking window.
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Emos P5623 – WiFi thermostat – a room thermostat with WiFi connectivity and a mobile app in which you can set and monitor the weekly program and operating history remotely. Price from €122.75. |
Five factors covered in the introduction of the article.
Practical tips covered in the second part of the article.
Control as the main tool for heating savings.
Frequently Asked Questions
- How much will I really save if I set up weather compensation control? An exact figure can't be guaranteed, since it depends on the specific house, the previous heating method, and the settings. In practice, when switching from manual settings to good-quality weather compensation control, people commonly talk about an approximate saving on the order of 10 – 15%, but take this as a rough guide, not a guarantee.
- Is night setback suitable for every house? A moderate setback (typically 2 – 3 °C) is suitable for most normally insulated houses. In an older, less well-insulated house, we recommend a milder setback instead, since a sharp morning reheat can reduce part of the savings. It's best to try it and see the result.
- How often do radiators need to be bled? We recommend checking for air at least once at the start of the heating season, and then any time you notice the top of a radiator staying cold or hear bubbling in the pipes – these are typical signs of air in the system.
- Do I also need a room thermostat for weather compensation control, or is the outdoor sensor enough? The outdoor sensor alone can control the boiler based on the outdoor temperature, but a room (or directly weather-compensating) thermostat adds the comfort of precise settings and a time program based on the real indoor need. Combining both is the common and recommended approach.
- Is a water filter worth it if I have a new boiler? Yes – the filter protects the heat exchanger from deposits and mechanical dirt right from the start of operation, helping to maintain the boiler's high efficiency in the long run, not just in the first few years.