What is a Boiler Pump Overrun Function? All You Need to Know!

Pump overrun on your boiler is a crucial function that is often overlooked. Understanding what boiler pump overrun is and how it functions is essential for homeowners. Pump overrun refers to the continued operation of the central heating pump after the boiler has switched off.

This article aims to provide a comprehensive overview of boiler pump overrun, its purpose, components, benefits, problems and troubleshooting techniques, energy efficiency considerations, and maintenance tips.

By delving into these aspects, you will gain valuable insights into optimising your boiler’s performance and achieving optimal comfort and energy efficiency in your home.

What Does a Pump Overrun Mean?

If you have ever wondered why your boiler continues to run even after turning it off, you may have encountered the concept of a central heating pump overrun. However, worrying is unnecessary, as it is a simple concept. Pump overrun refers to the continued operation of the central heating pump in your system for a short time after the boiler has been switched off.

Now, let us delve a little deeper into the purpose of a pump overrun. When you turn off your boiler, the pump overrun function is activated. This function ensures that your pump continues to run for a short period, typically lasting 5–10 minutes. You will need a pump overrun thermostat or a timer set for a specific duration to control this function effectively.

By passing the hot water through a bypass valve and circulating it, the pump overrun operation helps dissipate any residual heat, thereby reducing the risk of hot water boiling inside and causing damage to your boiler components. Additionally, it would be best to have a bypass circuit piped in, depending on whether you have an S-plan or a Y-plan heating system.

It is worth noting that the pump overrun function is commonly found in heat-only boilers, as some larger and sturdier boilers have an in-built function to handle the residual heat, eliminating the need for pump overrun.

Related Article: S Plan Vs Y Plan Heating Systems: Benefits, Drawbacks, And Comparison

Components Involved in Pump Overrun Functionality

To make a pump overrun work, there are a few components involved. The control mechanism, often integrated into the boiler or as part of a separate controller, is responsible for monitoring and initiating the pump overrun function. The pump and motor also work together to keep the water flowing during this extended operation period.

So, the next time you hear your boiler humming away even after you’ve turned it off, remember that it’s just the trusty pump overrun doing its job to keep you warm, cosy, and energy efficient.

Benefits of utilising a central heating pump overrun

• Improved Efficiency and Energy Savings

  
  

By allowing the remaining heat in your system to be fully utilised, pump overrun improves the overall efficiency of your boiler. This means less energy waste and lower energy bills, giving your wallet and the environment a reason to smile.

• Enhanced Comfort and Temperature Control

  
  

With pump overrun, you can bid farewell to those annoying cold patches in your home. By circulating the water, pump overrun ensures that every nook and cranny of your living space receives a steady flow of warmth. So, say goodbye to chilly toes and hello to cosy evenings.

Identifying Common Problems with Pump Overruns

Pump overrun is a great feature that helps circulate hot water even after the boiler has turned off. However, like any other system, it can sometimes run into issues. To identify the cause, look for the following problems:

1. No Pump Operation

If you notice that the pump isn’t running even when the boiler is on, there might be an electrical issue, or a faulty pump printed circuit board (PCB).

2. Continuous Pump Operation

One of the common issues that many homeowners face related to their pump’s overrun function is that it keeps running for hours rather than 5–10 minutes. Conversely, if the pump keeps running indefinitely, even when the boiler is off, there might be an issue with the thermostat or a faulty control valve.

3. Insufficient Heat Circulation

If the radiators in your home aren’t getting adequately hot, it could be due to poor pump performance or trapped air in the system.

How to Fix Pump Overrun on Boiler

When you encounter pump overrun issues, here are a few troubleshooting techniques you can try:

1. Check the Power Supply

Make sure the pump is receiving power. Check the fuse box or circuit breaker to ensure there are no issues. Sometimes the reason behind a pump overrun fault is a broken PCB on your boiler’s pump. To fix it, you must contact a Gas safety Engineer.

2. Examine the Pump Settings

Ensure that the pump is set to the correct speed and flow rate. Incorrect settings can affect its performance.

3. Bleed the Radiators

If you suspect trapped air in the system, bleed the radiators to release the air and improve heat circulation.

4. Inspect the Thermostat

Test the thermostat by adjusting the temperature settings. The thermostat may require calibration or replacement if the pump operates according to the changes.

5. Consult a Professional

If you cannot identify or resolve the issue, it’s best to seek assistance from a qualified heating engineer or technician who can diagnose and fix it.

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Impact of Pump Overruns on Energy Consumption

While pump overrun may consume some energy, it is essential for maintaining optimal heating efficiency. The additional hot water circulation helps distribute heat evenly throughout your home, eliminating cold spots and reducing the need for the boiler to operate frequently.

Calculating Potential Cost Savings with Pump Overruns

Calculating precise cost savings with pump overruns can be challenging due to various factors influencing energy consumption. However, by reducing the frequency of boiler cycles and ensuring efficient heat distribution, pump overrun can lower your heating bills. The improved comfort and reduced wear and tear on the boiler can also contribute to long-term cost savings.

Maintenance Tips for Central Heating Pump Overrun Systems

To keep your pump overrun system running smoothly, here are a few maintenance practises to consider

1. Get an annual boiler service.

2. Inspect the pump regularly for signs of wear or damage. Replace any worn-out parts promptly.

3. Clean and remove any debris or sludge accumulating in the system to ensure efficient operation.

4. Check the circulating pump’s impeller to ensure it spins freely and isn’t obstructed by objects.

5. Test the pump overrun function periodically to ensure it activates and deactivates correctly.

Tips for Optimising Pump Overrun Performance

For optimal pump overrun performance, keep in mind these helpful tips:

1. Set the pump speed and flow rate according to the specific requirements of your heating system.

2. Consider installing thermostatic radiator valves to control the heat output more precisely and reduce unnecessary pump operation.

3. Insulate your pipes and boiler to minimise heat loss and improve energy efficiency.

4. Regularly bleed your radiators to eliminate trapped air, allowing heat to circulate more effectively.

Conclusion

In conclusion, central heating pump overrun is vital to maintaining efficient and effective boiler systems. By understanding its purpose and benefits, homeowners can harness the advantages of pump overrun to enhance comfort and energy efficiency. Regular maintenance and adherence to best practises ensure optimal pump overrun performance.

By implementing these strategies and troubleshooting techniques, homeowners can optimise their boiler’s performance, reduce energy consumption, and enjoy a cosy and comfortable living environment.

However, if you are facing other issues related to your central heating system or looking for a new boiler, please get in touch with us on 0345 3192 247, and one of our representatives on call will assist you with your problem.

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