Boiler Flow Temperature: Best Settings to Make Savings

Primarily, the boilers are meant for heating homes, though they also provide hot water in taps and showers. In cold weather, a boiler must operate continuously, around the clock, without interruption, to keep the home warm and comfortable. It consumes a considerable amount of energy to keep the boilers consistently in operation. The majority of UK homes have gas boilers that require a continuous gas supply, which often costs more than expected. A higher energy bill, among other factors, can be caused by an incorrect boiler flow temperature setting.

Properly setting and adjusting the boiler's flow temperature is key to reducing energy bills without compromising home comfort and warmth. It is one of the simplest and most effective ways a homeowner can take to control the ever-increasing energy bills. The experts believe that most homes incur extra gas costs simply because they keep them unnecessarily hotter than necessary.

This article will help you understand what a boiler flow temperature is and how to set it to reduce energy bills.

Understanding Boiler Flow Temperature

The process of heating the homes starts with heating the water in the boiler. This heated water is transported to radiators, which are installed in different rooms in the home to provide heating. The temperature of the hot water, which a boiler transports to radiators, is known as “boiler flow temperature”. It should not be confused with the hot water temperature in the taps and showers; these are two different things.

The boiler flow temperature can be better understood by the process of water flow in the central heating system, which can be summarized as follows:

·         The boiler heats the water up to a preset temperature.

·         The heated water flows from the boiler to the radiators.

·         After heating the rooms, the water in the radiators flows back to the boiler.

·         During the process of heating the rooms, the hot water is cooled a bit.

·         This relatively cold water is heated again up to the preset temperature level.

Although modern boilers, such as a combi, come with a preset flow temperature of around 70 to 80°C, an option of manually setting this temperature is also provided in them. This option differs with the make and model of the boiler; it may either be in the shape of a dial or a digital control panel.

The preset boiler flow temperature of 70 to 80°C is based on providing maximum heating, which often proves to be highly costly. For better energy efficiency, without compromising the comfort of the home, this temperature needs to be adjusted to a correct setting. A lower boiler flow temperature works best in modern condensing boilers because the process of condensation works only when the water coming back from radiators is colder than 55°C. The condensing does not effectively occur if the temperature of this water is above 60°C.

Impact of Flow Temperature on Boiler Efficiency

Lowering the flow temperature works best in condensing boilers when it comes to making savings in energy bills. Condensing boilers recover additional heat from exhaust gases, helping reduce energy consumption. Their efficiency improves when the water returning from the radiators is colder, facilitating condensation inside the boiler. This process needs a temperature typically less than 55°C. If the flow temperature is too high, the water coming back to the boiler often remains above this threshold, preventing proper condensation.

The impact of a lower flow temperature is as follows:

1.       It allows sufficient condensation inside the boiler.

2.       It reduces the overall gas consumption.

3.       It improves the overall boiler efficiency.

4.       It reduces the emission of carbon.

5.       It goes a long way in increasing the useful life of a condensing boiler.

IMPORTANT

Correctly setting the boiler flow temperature can save around 9 to 13% on energy bills.

Boiler Flow Temperature – Best Settings To Make Savings

Generally, there are two different heating systems used in the majority of homes: the "radiator heating system" and the "underfloor heating system". The boiler flow temperature setting is different for both systems. Moreover, the optimal boiler flow temperature to reduce energy bills varies with the home's requirements, insulation level, and heating system type.

1.       Radiator Heating System – The experts recommend that a radiator-based heating system works best at a flow temperature between 55 and 60°C. Setting the flow temperature at 60°C is recommended when the weather is severely cold. During milder cold weather, the flow temperature can further be lowered to 50°C for optimum comfort and energy efficiency. These recommendations apply to well-insulated homes with a condensing boiler.

2.       Underfloor Heating System – An underfloor heating system is designed to perform well at much lower flow temperatures because it is already highly energy-efficient. The best setting for this type of heating system is 35–45°C. However, homeowners should also consider the manufacturer's recommendations to maximize savings on energy bills. Again, the best performance and higher energy efficiency largely depend on proper home insulation.

The recommendations of an expert, well-qualified boiler installer can also be considered when setting the boiler flow temperature to maximize savings. 

Flow Temperature Settings – Wrong Practices By Installers

In many cases, an installer often sets the boiler flow temperature to a higher degree as a default setting. The purpose of this practice is to ensure that homes reach the desired heating level quickly. Another consideration for the installers is avoiding complaints from homeowners about insufficient heating. This is a completely wrong practice by installers, which every homeowner must understand. It is expected that a well-qualified and experienced boiler installer should educate the users on this aspect of temperature setting.

This wrong practice results in:

·         Higher energy bills.

·         A reduced condensing efficiency of the boiler.

·         Higher possibilities of wear and tear of the internal components of the boiler.

·         Inconsistent or uncomfortable heating.

Adjusting The Boiler Flow Temperature – Step-By-Step Procedure

·         Find the temperature control for the heating system. This can be located on the boiler or thermostat. It is often in the form of a dial or digital control panel. Sometimes it is also in the form of a rotatable knob with temperature settings displayed as numbers, with 1 being the lowest.

·         The control is marked with “flow temp,” “heating temperature,” or just a radiator icon.

·         By default, the temperature is generally set at 70°C. Reduce it gradually. First, try to set it to 60°C.

·         Keep watching the impact of this setting for a few days. If it does not compromise the overall heating comfort, continue with it. Otherwise, it can be further reduced or slightly increased, depending on your comfort level.

·         In a milder winter, autumn, or spring, the temperature can be reduced further to 50°C.

·         If the control is a numbered knob, it might be set to 3 or 4 by default. Turn the knob to 2, which normally refers to a temperature setting of 60°C.

Factors Affecting The Flow Temperature Setting

1.       Home Insulation – A well-insulated home can retain heat; therefore, a lower temperature can be a viable option. If the home is poorly insulated, the temperature will have to be maintained at a higher degree.

2.       Size and condition of the Radiator – A larger radiator emits more heat with greater efficiency. An undersized or old radiator will need a higher temperature setting.

3.       Weather Conditions – In severely cold weather, a higher flow temperature will be required to keep the home comfortable. In milder cold weather, the temperature can be lowered.

4.       Heating Controls – Smart thermostats automatically adjust boiler operation for maximum efficiency. These systems can further improve savings when adjusted to a lower flow temperature.

FAQs

1.     What is the best boiler flow temperature for UK homes?

While it depends on some other variable factors as well, the best recommended flow temperature for UK homes is 60°C.

2.     Can I adjust the boiler flow temperature on my own?

Yes, the modern boilers, especially the combi boilers, have the option for homeowners to adjust the flow temperature on their own.

3.     Will lowering the boiler flow temperature make my home colder?

Not necessarily. A prudently adjusted flow temperature would operate efficiently without affecting your home's heating.

4.     How much can be saved by lowering the flow temperature?

Adjusting the flow temperature to a correct setting can save you 9 to 13% on energy bills.

5.     Are flow temperature and hot water temperature the same?

No, flow temperature is the temperature of water flowing towards radiators, whereas the hot water temperature is the temperature of water available in taps and showers. These are two different temperatures.

Conclusion

Most modern homes use gas boilers for heating. In extreme cold, these boilers must run continuously to provide consistent heating. It often results in a higher energy bill. This energy consumption can be reduced considerably by lowering the boiler flow temperature. It is estimated that lowering the flow temperature can save homes 9 to 13% on energy bills. Modern condensing boilers, especially combi boilers, allow users to adjust the flow temperature themselves without calling a boiler engineer. Ideally, lowering the flow temperature to 60°C can significantly reduce energy bills without affecting the overall heating of homes. The temperature can be further lowered to 50-55°C in milder weather conditions.