When and how to purge a heater ?

The boiler distributes the water in the heating circuits, and each radiator then emits heat according to the requested temperature. But sometimes air has collected in the pipes, causing a mess in the entire heating system. As a preventive or curative measure, purging the radiators of a home is therefore sometimes necessary. How does it operate? And when should we purge? We guide you.

What is a radiator bleed, and what does it do?

Bleeding a radiator consists in evacuating the air which is inside. Air ? And yes, air that has accumulated during installation, or during the period when the radiators are not running because the interior temperature is sufficient. The results ? Visualize a DIY spirit level. The air bubble moves and takes the place of the water, which prevents it from circulating properly. In a closed circuit like the heating one, this can lead to malfunction and damage the radiators, not to mention the fact that the heating provided will be unsatisfactory. Bleeding is therefore a means of optimizing the performance of the heating installation.

When should you bleed the radiators?

In general, it will be a good idea to bleed all the radiators in a home before the heating period, so once a year. Why this period? This is rather obvious, since it is during the months that follow that the radiators will be the most stressed, so that we ensure optimal operation. Once a year, it is for preventive purposes and it is necessary. On the other hand, it will sometimes be necessary to bleed the radiators in the event of a heating malfunction.

Indeed, if you notice, despite a working boiler, that your radiator is cold, or that only part of the radiator is hot, that its efficiency is decreasing, that the feeling of heat is not satisfactory, or that you hear noises such as hissing or water flowing, it’s a safe bet that a purge is necessary to eliminate the air which has probably accumulated in the installation.

It should be noted that a radiator that has not been drained for several heating seasons will in the medium term present leaks at the level of the connection pipes, and will risk damaging the boiler. Indeed, the heating body will work in a forced way to compensate for the presence of air bubbles which do not diffuse heat, and the circulation pump to be damaged by dint of propelling water charged with air bubbles in the pipes.

How to bleed a radiator?

A radiator bleed is a fairly simple operation to perform. It must be carried out cold, but the boiler can remain in operation. Before starting, you will need to equip yourself with a screwdriver and a container to collect the water that will flow from the system.

To begin, it will be necessary to locate what is called the radiator bleeder. It is a screw surrounded by a kind of white button, located opposite the pipes, at the top of the radiator. And here is the action, you will have to turn this screw to let the air escape from the radiator, and that’s it. We told you, nothing really rocket science in this manipulation. A small nuance all the same, this system concerns rather recent radiators. The oldest also have a bleeder, but the designers had not yet perceived the interest of the screw to be unscrewed. So, it will be necessary to equip yourself with pliers to turn the trap, but the principle remains the same.

Don’t panic, a little water flows out at the same time as the air, and that’s normal. But how do you know when to stop the purge? Let’s say that it will be necessary to let the water flow to fill the equivalent of a small glass, but no more.

It’s over, or almost, since a purge should not be done on a single radiator. Remember that all the radiators in a home are interconnected from the boiler. It will therefore be necessary to bleed each radiator, starting with the one closest to the boiler, then by bleeding the following ones, always in the order from closest to farthest to respect the piping circuit. And of course to finish, don’t forget to screw the trap back on!

Why rely on foresight?

We told you, an annual purge is preventive. When doing so, it will not be uncommon for the flowing water to be not very clear, or even appear somewhat muddy. This can happen on an old network, or on more recent systems where preventive products have not been integrated. Sludge can be caused by scaling, corrosion, or the presence of microorganisms in the networks. Sludge is therefore impurities that prevent the proper circulation of water in the circuit, and can continue to destabilize the boiler and the heating system, causing excessive energy consumption. In this case, it will be necessary to perform a sludge removal.

It is a cleaning of the accumulated mud deposits, which we will say sludge removal. A machine can then send pressurized water into the network to clean it, or inject a product which will act for 24 to 48 hours before being evacuated by a drain with the suspended mud particles.

After purging, pressure check

By purging each of the radiators in the house, and letting the equivalent of a small glass of water flow for each one, it’s a safe bet that the circuit lacks water, which will not be observed. a drop in pressure. After a purge, it will therefore always be necessary to check the pressure of the boiler, which must be between 1 and 1.5 bar. Too low, therefore less than 1 bar, the pressure must be rebalanced.

To do this, the handling is again very simple. It will suffice to open the filling valve identified and generally accessible under the boiler. Once the correct level of pressure has been reached, close the valve.

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