A gas boiler filling loop is a crucial component in maintaining the optimal pressure of your central heating system. It is a hose that connects your mains water supply to your boiler, allowing you to repressurize the system when the pressure is too low or too high. This comprehensive guide will cover the technical details of gas boiler filling loops, including their location, usage, types, and technical specifications, as well as essential DIY tips and precautions.
Where Can I Find the Filling Loop on My Gas Boiler?
The location of the filling loop on your gas boiler depends on the type of loop you have. There are two main types: internal and external.
- Internal Filling Loop:
- This type of loop is usually found within the boiler itself, often behind a hatch or flap.
- It is commonly found in combi boilers and has two valves: one connecting to the boiler and the other to the main water supply.
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The internal filling loop is typically made of copper or stainless steel and has a diameter of 15mm or 22mm, depending on the boiler model.
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External Filling Loop:
- This type of loop is fitted outside the boiler and connects the mains water supply to the central heating system.
- It is often located near the boiler or a remote expansion vessel.
- The external filling loop is usually made of flexible hose with a diameter of 15mm or 22mm, depending on the system requirements.
How Do I Use the Filling Loop to Repressurize My Gas Boiler?
Using a filling loop to repressurize your gas boiler is a straightforward process. Here are the steps:
- Turn Off the Boiler:
- Ensure the boiler is switched off to avoid any damage or performance issues during the process.
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This step is crucial to prevent the boiler from automatically firing up and potentially causing water damage or personal injury.
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Locate the Filling Loop:
- Find the filling loop, whether internal or external, and ensure it is connected to the boiler and the mains water supply.
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Check that the isolating valves on the filling loop are in the closed position before starting the process.
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Remove Caps and Connect the Loop:
- Remove any caps from the valves and connect the filling loop to the filling taps.
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Tighten the connections by hand to ensure a secure and leak-free seal.
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Open the Isolating Taps:
- Turn the isolating taps to align with the pipe, allowing water to flow into the boiler.
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You will hear a hissing noise and see the pressure gauge rise as the system is repressurized.
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Monitor the Pressure Gauge:
- Check the pressure gauge regularly to ensure it reaches the recommended level of 1 to 1.5 bars.
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If the pressure is too high, bleed the radiators and start the process again.
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Close the Isolating Taps:
- Once the desired pressure is reached, turn the isolating taps to point across the pipe, stopping the water flow.
- This step is crucial to maintain the correct pressure in the system and prevent any further water ingress.
What Are the Types of Filling Loops Available for Gas Boilers?
There are two primary types of filling loops available for gas boilers:
- Internal Filling Loop:
- This type is integrated into the boiler and has two valves controlling water flow and preventing backflow into the mains.
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The internal filling loop is typically made of copper or stainless steel and has a diameter of 15mm or 22mm.
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External Filling Loop:
- This type is fitted outside the boiler and connects the mains water supply to the central heating system.
- It also has two valves controlling water flow and preventing backflow.
- The external filling loop is usually made of flexible hose with a diameter of 15mm or 22mm.
Technical Specification of Gas Boiler Filling Loop
- Pressure Range: The ideal pressure range for a gas boiler is between 1 and 1.5 bars when the heating is off and can rise to around 2 bars when the heating is on. Exceeding this range can lead to system issues and potential damage.
- Valves: Filling loops typically have two valves: one controlling water flow and the other preventing backflow into the mains. These valves are usually made of brass or stainless steel and have a working pressure of up to 10 bar.
- Hose Material: Internal filling loops are often made of copper or stainless steel, while external filling loops are typically made of flexible hose. The hose material should be suitable for potable water and have a working pressure of at least 10 bar.
- Hose Diameter: The diameter of the filling loop hose is usually 15mm or 22mm, depending on the boiler model and the size of the central heating system.
- Connections: The filling loop connections to the boiler and the mains water supply are typically threaded, with a size of 1/2″ or 3/4″ depending on the system requirements.
DIY Tips and Precautions
- Ensure the boiler is off before starting the process: This is crucial to prevent any potential damage or safety hazards.
- Check the pressure gauge regularly to avoid over-pressurizing: Exceeding the recommended pressure range can lead to system issues and potential damage.
- Bleed radiators if the pressure is too high: Releasing excess pressure from the radiators can help maintain the correct system pressure.
- Consult a professional if you are unsure about the process or if you need to repressurize more frequently than twice a year: Frequent repressurization may indicate an underlying issue that requires professional attention.
References
- Ideal Heating. (2020). How to Refill Your Boiler – YouTube. Retrieved from https://www.youtube.com/watch?v=tbz17NC7y9A
- BOXT. (2022). How to repressurise your boiler with a filling loop – YouTube. Retrieved from https://www.youtube.com/watch?v=MxyA4SJ7Fz0
- Newave Education. (2013). How To Repressurise A Boiler With A Flexible Filling Loop – YouTube. Retrieved from https://www.youtube.com/watch?v=BQ9tHmFm-xI
- Boiler Central. (n.d.). Boiler Filling Loop, What is a Filling Loop & How to Use it? Retrieved from https://www.boilercentral.com/boiler-advice/boiler-filling-loop/
- Heatable. (n.d.). What is a Boiler Filling Loop Valve? Expert Guide – Heatable. Retrieved from https://heatable.co.uk/boiler-advice/what-is-a-boiler-filling-loop