In brief: The right flow temperature is the key to efficient heating. It is often lower than you might think. Modern condensing boilers with underfloor heating need only 35-45°C. Old radiators require 50-70°C. Lower the temperature gradually by 1-2 degrees and check whether the rooms stay warm. Every degree less saves around 6% energy.
Set Your Heating Flow Temperature Correctly & Save Energy
The flow temperature setting directly affects your heating costs. Many households heat with temperatures that are too high. This puts pressure on your budget and the environment. With the right strategy, you can optimise your heating system and improve energy efficiency throughout your home.
We show you how to adjust the temperature. You will learn how to improve heat distribution and maintain your home comfort. Practical steps will help you achieve your goal.
What is the heating flow temperature?
The flow temperature is the temperature of the heating water as it leaves the boiler. This warm water flows through the pipes to the radiators or underfloor heating. There, it gives off heat and cools down.
The cooled water flows back to the boiler as return water. The difference between the flow and return temperatures is crucial for efficiency. A low return temperature means that a lot of heat has remained in the room.
“The flow temperature is the number one control for the efficiency of a heating system. It is often 10 to 20 degrees higher than the value actually required.”
Why is the correct setting so important?
A flow temperature set too high leads to wasted energy. The boiler heats the water to an unnecessarily high level. The radiators become extremely hot and the rooms quickly overheat.
You then have to turn down the thermostatic valves. This leads to expensive stop-and-go operation. The heating system constantly fluctuates and consumption increases. Modern condensing boilers also work most efficiently at low temperatures.
Important note
Only change your heating settings if you know what you are doing. If you are unsure, consult a qualified heating professional. Incorrect settings can cause frost damage or a drastic loss of comfort.
The effects on different heating systems
Not every system needs the same temperature. Underfloor heating works with 35 to 45 degrees Celsius. It has a large surface area for transferring heat.
Old radiators with a small surface area often need 55 to 70 degrees. Modern panel radiators fall somewhere in between. Your heating system determines the potential for savings. You can find suitable heating pipe insulation in our category.
How do I find my optimum flow temperature?
Proceed systematically. Make a note of the current setting on the boiler. Lower the flow temperature gradually by one or two degrees.
Over two days, observe whether all rooms still reach a comfortable temperature. This is particularly important on cold days. Repeat the process until you find the lower limit.
Pro tip
Do not use the “night setback” too aggressively. Lowering the night-time temperature too much forces the system to use a high flow temperature in the morning to heat up again. A constant, lower basic temperature is better.
The role of the heating curve
The heating curve controls the flow temperature according to the outdoor temperature. In severe frost, it sets a higher temperature than in mild weather. A flatter heating curve is usually more efficient.
You do not have to adjust the curve linearly. Often, it is enough to lower the entire curve slightly. Modern heating systems offer automatic optimisation of this setting.
Practical steps for adjusting the setting
1. Find the control panel for your boiler. It is often a digital display with menu buttons.
2. Navigate to the settings for the heating flow temperature or heating curve.
3. Reduce the target value by two degrees.
4. Check the room temperatures in all rooms the next day.
Products such as a Radiator Sealant can help repair leaks in the system that reduce efficiency. A leak-free system is the basis for any optimisation.
Further measures for optimising your heating system
The flow temperature is just one factor. For overall energy efficiency in your home, combine several steps. Start by bleeding the radiators. Air in the system interferes with heat distribution.
Then check the hydraulics. Are all radiators evenly warm? If not, you may need hydraulic balancing. This sets the optimum water flow for each radiator.
“Hydraulic balancing is the investment with the shortest payback period in heating technology. It can reduce heating costs by a further 10-15%.”
Insulating pipes and radiators
Uninsulated heating pipes in unheated areas such as the cellar release heat unnecessarily. This artificially lowers the return temperature and reduces boiler efficiency. Insulate these pipes with suitable pipe shells.
For other outdoor insulation tasks, such as protecting equipment, our mesh tarpaulins are suitable. Products such as the Transparent Tarpaulin 3x4m or the Transparent Tarpaulin 4x5 protect sensitive items.
Additional advice
Programmable thermostatic radiator valves are the perfect addition to central heating control. They automatically lower the temperature when you are asleep or away from home, without changing the flow temperature at the boiler.
Special situations: older homes and underfloor heating
Optimising heating in older homes
Older homes often have less insulation and larger radiators. They generally need a higher flow temperature. Even so, lowering it by 5–10 degrees can often lead to significant energy savings.
Combine the temperature adjustment with other measures. Seal your windows. Use clear covers to block drafts around doors in winter. The large 4x6 transparent tarpaulin can work as a temporary windbreak.
Setting underfloor heating correctly
Underfloor heating systems respond slowly to temperature changes. Set the flow temperature especially low; 35 degrees is often enough.
Avoid large temperature swings. A steady, low temperature provides the best living comfort and greatest efficiency. The large heating surface makes up for the low flow temperature.
When you need a professional
Some settings aren’t accessible to homeowners. Contact a heating professional if your radiators don’t get warm enough even when the flow temperature is set high, or if your heating system makes unusual noises.
You may also need professional help if you can’t find the heating settings on your boiler, or if your system is very old and has only mechanical controls. A professional can also identify and optimize hidden opportunities to improve efficiency, such as adjusting the pump settings.
For other projects around your home and garden, find inspiration and supplies in our shop or in the Plumbing & Irrigation section.
Conclusion: more comfort, lower costs
Finding the right flow temperature is simple and can make a big difference. You can start saving energy right away while protecting your heating system. Living comfort stays the same or may even improve with more even heat.
Start lowering the temperature gradually today. Combine this step with bleeding your radiators and using smart heating controls. Your wallet and the environment will thank you.
Frequently Asked Questions
- What is a heating system’s flow temperature?
- The flow temperature is the temperature of the water as it leaves the boiler and enters the heating pipes. It’s set at the heat source and determines how much heat reaches your radiators or underfloor heating. If it’s set too high, energy is wasted.
- How do I find the right flow temperature for my home?
- The right temperature depends on your heating system and how well your home is insulated. Start at around 45°C, then raise the setting gradually until every room is comfortably warm. Modern condensing boilers work most efficiently with flow temperatures between 35°C and 55°C.
- Can adjusting the flow temperature really lower my heating bills?
- Yes. Each degree Celsius you lower the flow temperature can reduce energy use by around six percent. Lowering it from 70°C to 55°C can therefore save more than 20%. Just make sure your rooms still reach a comfortable temperature.
- Should I set a different flow temperature in summer?
- In summer, if you only need hot water, you can often lower the heating curve all the way or turn off heating mode. The flow temperature for hot water alone is typically 50-60°C to help prevent Legionella growth.
- What’s the difference between flow temperature and return temperature?
- The flow temperature is the warm water that travels to the radiator. The return temperature is the cooler water that flows back from the radiators to the boiler. Keeping the return temperature as low as possible improves efficiency, especially with condensing boilers.
You might also be interested in
- Set your heating thermostat correctly: save money & energy
- Hydronic balancing saves heating costs and improves comfort
- Heat your home correctly & save energy: tips for your home
- Reduce heating costs: bleed radiators and heat your home correctly
- Replace your radiator thermostat and reduce heating costs
- Reduce heating costs: sensible overnight heating setback