1. How to carry out a visual inspection of the outside of your boiler

An error message on the boiler display is an obvious warning sign. But even a small trace of moisture on the floor beneath the appliance could indicate that something is about to go wrong. That is why carrying out an initial visual inspection can help you prevent potential faults in your heating system. What should you look for during this inspection?

• Signs of moisture on or around the boiler.
• Potential drips from the pipework.
• Signs of corrosion, rust or damage.
• Damaged or poorly connected power cables.
• Problems with or damage to the on/off switch.
• Error messages on the display.

2. How to check and prepare the ventilation grilles

As well as being a mandatory safety feature, ventilation grilles help prevent toxic gases from building up inside your home.

Ideally, the grilles should be kept clean and unobstructed throughout the year, but the start of the heating season is a good time to carry out the three most important checks:

• Make sure the grilles are not blocked.
• Ensure no dirt has built up between the slats.
• Make sure there is no furniture or objects placed in front of them.

3. How to check your boiler pressure

The boiler pressure is checked using a small pressure gauge, usually located on the front or underside of the appliance. In most cases, when the heating is switched off, the needle should read between 1 and 1.5 for the system to operate normally. However, it is important to check your boiler's instruction manual to find out the pressure recommended by the manufacturer.

What happens if your boiler pressure is too low or too high?

If the pressure is too low, the water flowing from the boiler to the radiators will not have enough pressure to reach them all. As a result, some parts of the house may remain cold even when the heating is on.

At the other extreme, if the pressure is too high, all system components are subjected to more pressure than they should be. If pressure remains high, it can damage the pipes and radiator valves and may even cause the boiler to shut down as a safety measure.

How can you increase the pressure in the heating system?

First, check the boiler's instruction manual to find out where the pressure valve is located. Once you have located it, turn it carefully until you hear water flowing. When the pressure gauge shows that the pressure has reached the desired level, close the valve again.

If the pressure repeatedly drops after you have adjusted it, there may be a leak in the system or a fault with the sensors. In this case, contact the technical support service.

How can you reduce the pressure in the heating system?

As a general rule, it is worth knowing that the valve used to increase the pressure cannot also be used to reduce it. Therefore, if the pressure gauge is above the correct values, there are three possible solutions:

1. Check whether the instruction manual explains how you can reduce the system pressure yourself.
2. If not, try draining some water from the radiator closest to the boiler until the pressure gauge returns to the recommended level. To do this, you can follow the advice on bleeding radiators in this article on our blog.
3. If neither of the above methods works, contact the technical support service for instructions or to arrange a visit from a professional.

How to check your radiators before you switch on the heating

Once you have confirmed that the system pressure is sufficient for heat to reach every radiator, it is time to check their condition. Check that:

• The valves open and close properly without having to force them.
• There are no water leaks or damp marks on the walls or floor.
• There is no furniture or other objects placed in front of them that could obstruct the flow of heat.
• There are no delicate fabrics or flammable materials next to them.
• No air has built up inside them over the summer.

How can you tell if a radiator has air in it, and how does this affect your heating?

When radiators have been inactive for months, some air can seep into the system. This air takes the place of some of the water that should be in the system, preventing the radiator from heating normally. For this reason, it is advisable to bleed all your radiators as part of your preparations for the winter season.

These are the signs that could indicate the presence of air:

• You hear water or dripping noises coming from inside the radiator.
• The top of the radiator is cooler.
• Your home heats up unevenly or more slowly than usual.

Why is it better to bleed radiators with the heating switched off?

There are two reasons why it is recommended to bleed radiators when they're cold:

1. If you do it while the heating is on, the water in the system will be above 50°C, and you could burn yourself if any water splashes out.
2. When the heating is switched off, the water is at rest, so the air remains at the top of the radiator, where it is easier to bleed.

Why should you check the boiler pressure again after bleeding the radiators?

When you remove the air from each radiator, you also lose some of the water in the system. This small amount, multiplied by the number of radiators in your home, causes the overall system pressure to drop. That is why it is a good idea to check the boiler's pressure gauge again after bleeding the radiators to make sure that it remains within the recommended levels.

How to ensure your thermostat is working properly

We sometimes forget that the thermostat is also part of our heating system, and a lack of maintenance or a minor fault can make us think that the boiler is faulty when it is not. To make sure the device will function as expected, check these five points:

• It is set to the right mode or function to activate the boiler.
• The battery or replaceable batteries are in good condition.
• The date and time are correct.
• The programming feature works properly.
• The heating reaches the temperature set on the thermostat.

How to switch on your boiler for the first time after summer

Once you have completed all the checks, switching on the heating for the first time will confirm that it is ready for the winter:

1. Activate 'heating' or 'heating and hot water' mode.
2. Turn up the thermostat to check whether the boiler starts up.
3. Leave the system running for a few minutes while keeping an eye on it.

What to check during the first 15 to 30 minutes of heating

When you start using the boiler again, it is not unusual for some things to take a little while to work properly. Paying attention during the first few minutes will allow you to make sure everything is in order:

• The boiler should start up and remain on without displaying any errors.
• Every radiator in the house should heat up fully.
• The house should reach the desired temperature.
• The system should maintain a stable pressure.
• There should be no water leaks from the boiler or radiators.
• There should be no unusual noises anywhere in the system.
• No unusual smells should appear.

The following table highlights some possible signs of a malfunction and what to do if they occur: