Adding Water to the Boiler

What Water Pressure Should the Boiler Have?

In the boiler, the circulating water transfers heat from the burned gas in the heat exchanger to the radiators or underfloor heating. For this, a pump, also known as a boiler pump, is used to move the water in the heating circuit.
If there isn’t enough water, heat will disperse poorly, risking damage to the boiler or one of its components, like the heating pump we mentioned.
To avoid this incident and the need to call a technician, it’s important to add water to the boiler. It is recommended to fill the heating device between 0.8 bar and 1.5 bar. Above this, there could be overpressure that the expansion vessel cannot contain.

Tools Needed to Add Water to the Boiler

No tools are required to add water to the boiler. You only need your hands!

How to Fill the Boiler with Water?

POLO:

In your boiler, the water pressure should be between 0.8 and 1.5 bar.
Below 1 bar, it is recommended to raise the pressure to 1.5 bar.
Just be careful not to exceed 2 bars; it's best to stay within the proper pressure range.

POLO:

To check this pressure is quite simple: just look at the pressure gauge on the front of the boiler.

THIERRY:

That's right, Polo. I sense that for this video, I won’t be very helpful.

POLO:

Now that it's just the two of us, let's take this moment to do things properly!
First step: turn off the heating.
It’s currently at 0.8 bar pressure. This isn’t good; we need to fill it.

POLO:

Next, you need to go under the boiler, at the connection plate, also called the manifold.
There, you’ll find different valves. To know which one allows filling, you’ll need to refer to the technical manual of the boiler! Depending on the model, the valve may look different.
If you can’t find any information, the valve is usually located between your cold water supply pipe (a small pipe) and a larger pipe (for heating). Often, there are symbols on the valve manifold that can guide you.
You need to open one or two valves depending on your boiler model. The pressure on the gauge increases more or less quickly as soon as you open the valve(s).

THIERRY:

Be careful not to overfill the boiler, or the water might overflow from the 3-bar relief valve. We said a maximum of 2 bars! Make sure to close the valves after adding water.

THIERRY:

I see that you’ve successfully filled it; very good! If you have to come back to the installation several times a year for this issue, there is likely a leak or the expansion vessel is deflated or even out of service.