Cool autumn mornings, a coughing boiler, tepid radiators: every fall, technicians see a flood of emergency calls for avoidable faults. For air conditioning and plumbing specialists, the message is clear: before winter, a few simple checks are enough to prevent discomfort, overconsumption, and risks to the installation. It’s still necessary to know where to start and what to check.
HVAC and plumbing experts summarize the priority in a clear directive: “Make sure to follow these steps to guarantee optimal operation,” they explain. Open valves, no leaks, correct pressure, bleed the radiators, a well-placed thermostat… This checklist, recalled by Spanish and French professionals, allows for stress-free preparation for the start-up of the boiler before winter. A routine of a few minutes that can prevent many bad surprises.
Boiler restart: the initial checks to do before winter
Even before pressing the start button, the pros recommend a visual inspection. You must check that all supply and return valves are open, that the pipes and radiators show no signs of dampness or droplets on the floor. A leak, even a small one, ends up damaging the installation. Radiators should also stay clear, with no furniture, curtains, or clothes placed on them.
The circulation of heat in the rooms also plays a key role. A radiator jammed behind a sofa or a thick curtain mainly heats the wall, not the room. Experts also recommend taking advantage of winter sun by lifting the shutters and opening the curtains during the day, then closing them in the evening. This simple habit reduces the need to use the boiler before winter.
Boiler pressure and radiator bleeding: the adjustments the pros recommend
Another essential point: the boiler pressure. On the manometer, most manufacturers recommend a value between 1 and 1.5 bar for normal operation, as recalled by the National Confederation of Installer and Fluid Associations (CONAIF). Too low a pressure prevents proper circulation of hot water, radiators stay tepid, and the boiler may go into safety mode.
When a radiator is hot at the bottom but cold at the top, or it emits gurgling sounds, trapped air is often the cause. “Bleeding the radiators is a fundamental task for the proper functioning of a heating system, because the presence of air can affect its efficiency and increase energy consumption,” notes Mario Rial Axpe, head of the technical department of CONAIF. He advises turning off the heating, gently opening the bleed valve, then waiting for the air to escape. “You must keep the valve open until the water comes out steadily; that is how you know the intervention was carried out correctly. In this way, we ensure the radiator expels the air it contains,” adds the CONAIF spokesperson, before recalling that you should then recheck the pressure on the manometer.
Thermostat, temperature and safety: the final steps for optimal heating
Once the boiler and radiators are adjusted, the specialists urge looking at the room thermostat. It should be located away from a heat source or a draft, to avoid skewing the measurement and triggering the boiler too often. For comfort, they recommend a temperature around 21 °C, each additional degree adding about 7% to the bill.
They also emphasize the value of thermostatic valves and programmable thermostats, which adjust heat to rooms and times and offer, according to cited studies, energy savings of 8 to 13%. Safety matters equally: clear air vents, a possible carbon monoxide detector, and seeking a professional if the pressure often drops or if some radiators stay cold.
