What is a boiler filling loop?
You might have heard of a boiler filling loop but may not know just how important it is, and the headaches it can save, when it comes to repressurising your boiler. That’s why we’ve put together this guide covering what a filling loop is, the different types, and how to use them. Read on to get started…
Defining a boiler filling loop
A boiler filling loop is a hose that enables a connection between the boiler, central heating system and mains water supply. Depending on the type of boiler you have you will need either an internal or external filling loop. Once all components are linked, water can be added to the system to bring it up to the desired pressure. There will usually be two valves on either side of the hose to allow access when they are open and to cut it off when they are closed. This ensures that you can repressurise the boiler to the exact level you need it, without the risk of topping it up too much as you can easily shut off the water supply.
How to use your filling loop
It might seem daunting if you’ve never used it before but using your filling loop effectively is very straightforward. Before you get started, it’s important to ensure that the valves are in the ‘off’ position. If the boiler has only been installed quite recently, your filling loop might be attached using blank caps.
- First, fix the filling loop firmly into place on both ends
- Rotate one valve so that it’s the same as the direction of the pipe
- Slowly turn the other filling loop valve so water starts coming through the water mains and into the system
- As water comes through, check the pressure gauge display, it should be rising as the pressure increases
- When the gauge reaches 1.4 bar, turn both the valves so the supply is closed off
Whilst it would seem more convenient to keep the filling loop attached to the boiler or leave it next to it, you’re not allowed to do this. Regulations state that when it’s not in use, the filling loop has to be completely disconnected from the boiler. Plus, if you did leave it connected, you’re running the risk of significant damage to the filling loop.
In addition, depending on the location of your boiler in the home, if someone knocks into it accidentally it could allow water to start trickling into the system again and cause the boiler pressure to rise too high – resulting in more problems and potential damage. If you find that you’re using your filling loop frequently to repressurise, it’s likely that you have a problem somewhere in the boiler system that needs addressing.
Types of boiler filling loops
Depending on what will best suit your needs, there are different types of filling loops that can be used to repressurise your system.
Internal filling loop
Internal filling loops can often be found within the boiler. It is also commonly referred to as a combi boiler filling loop, as it used in this type of system. One valve on the loop connects to the boiler and the other to the mains water supply. This is because they both have different roles with one valve controlling water flow and the other stopping water from going back into the mains (called the double check valve). If you’re repressurising your boiler for the first time and need to know where the loop is, you can access it behind a flap or hatch. There should be an area for the filling loop key to be inserted here.
External filling loop
An external filling loop also has two control valves, one for water flow and the other for the main lines. The key difference between this loop and the internal one is given away by the name. It is fitted to the outside of the boiler instead of inside it. To repressurise the boiler you will need to look underneath the unit for the valve connection. An external loop connects the mains water supply to the central heating system.
What if your filling loop isn’t working?
The filling loop is essential in keeping the boiler operating at peak performance for as long as possible. If the loop is not functioning correctly, it is probable that there is an issue with the boiler that needs to be addressed. Alternatively, it could be that one of the valves has become stuck and is not allowing the water to pass through.
If the valve is stuck and you think you can free it, do so carefully as to not cause any damage to the loop. In the event that the boiler is the source of the issue, get in touch with a Gas Safe engineer to take a look at it and diagnose the problem and go from there.
Conclusion
If you’re having trouble with your filling loop and need a boiler filling loop replacement, NBS can help. We provide high quality new and refurbished boiler replacement parts at affordable prices. Explore our online shop to find the exact boiler loop you need for your system to get it back up and running quickly and efficiently whilst saving you money. Contact us if you have any questions.