Everything You Need to Know About Boiler Filling Loops

16 Mar by Will Kruse

Everything You Need to Know About Boiler Filling Loops

A boiler filling loop is a device used to fill a boiler with water. It is a simple device that consists of a valve and a gauge. The valve is used to control the flow of water into the boiler, and the gauge is used to monitor the pressure of the water in the boiler.

The boiler filling loop is an important part of a boiler, as it ensures it is filled with the correct amount of water. If the boiler is not filled with enough water, it will not be able to produce the right amount of heat. This can lead to a number of problems, such as the boiler not being able to heat the house properly or the boiler breaking down completely.

It is, therefore, essential to make sure that the boiler filling loop is working correctly and that the boiler is filled with the correct amount of water. If you are having any problems with your boiler filling loop, it is vital to contact a qualified technician who can help you fix the problem.

Why Do You Need a Boiler Filling Loop?

A boiler filling loop is a small plastic hose that is attached to your boiler. The other end of the hose is connected to a water supply, such as a tap. The purpose of the filling loop is to top up the water in your boiler when it starts to run low.

If your boiler is running low on water, it will need to be topped up. This is where the boiler filling loop comes in. The filling loop will allow you to connect your boiler to a water supply, such as a tap, and top up the water levels.

How Does a Boiler Filling Loop Work?

As part of the boiler commissioning process, a filling loop is used to fill the boiler and its associated heating system with water. The filling loop is a temporary connection between the mains water supply and the boiler and is used when the boiler is first installed or when the heating system is being flushed out.

The filling loop consists of a pair of hoses, one connected to the mains water supply and the other connected to the boiler. A valve is fitted to each hose, and a third valve is fitted between the two hoses. The filling loop is equipped with a pressure relief valve, which is set to open at 3 bar.

To use the filling loop, the two valves on the hoses are turned on and the valve between the hoses is opened. Water will flow from the mains water supply, through the filling loop, and into the boiler. The boiler will then start to heat up, and the water will expand.

This will cause the pressure in the system to increase, and the pressure relief valve will open, allowing water to flow out of the system and preventing the pressure from getting too high. Once the boiler has reached its operating pressure, the valve between the hoses is closed and the valves on the hoses are turned off. The filling loop can then be removed.


It is crucial to have boiler filling loops installed in your home for several reasons. First, they help ensure that your boiler always has the correct amount of water. This is important because if the boiler doesn’t have enough water, it can overheat and cause serious damage. Finally, boiler filling loops help to improve the efficiency of your boiler.

Do you need the help of an HVAC company in Berkeley? Turn to L.J. Kruse Co., a family-owned and -operated plumbing, heating, and cooling company located in Berkeley, California, serving residential and commercial clients. Request service now.

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