As the first chilly mornings arrive, a boiler that coughs and radiators that barely warm up—but not quite—signal another autumn when tradespeople see an influx of urgent calls for preventsable malfunctions. For specialists in air conditioning and plumbing, the message is unmistakable: before the cold season, a few straightforward checks are enough to spare discomfort, excessive energy use, and possible damage to the system. The catch is knowing where to begin and what exactly to inspect.
Cooling and plumbing experts distill the priority into a single, clear directive: “Make sure you follow these steps to guarantee optimal operation,” they explain. Open valves, no leaks, correct pressure, bleed the radiators, and position the thermostat correctly. This checklist, echoed by professionals from Spain and France, enables a stress-free prep for the boiler restart before winter. A routine that takes only a few minutes and can avert a lot of unwelcome surprises.
Boiler Restart: The Initial Checks to Do Before Winter
Even before pressing the start button, the pros recommend a visual inspection. Check that all supply and return valves are open, and that pipes and radiators show no signs of moisture or drips on the floor. A leak, even a tiny one, will eventually damage the installation. Radiators should also be kept clear, with no furniture, curtains, or clothing resting on them.
The flow of heat throughout the rooms also plays a key role. A radiator jammed behind a sofa or behind a thick curtain tends to heat the wall rather than the room itself. Experts also suggest taking advantage of the winter sun by lifting shutters and opening curtains during the day, then closing them in the evening. This simple habit reduces the need to run the boiler before winter arrives.
Boiler Pressure and Radiator Bleeding: The Adjustments Pros Recommend
Another essential point is the boiler pressure. On the gauge, most manufacturers recommend a value between 1 and 1.5 bar for normal operation, a guideline reiterated by the Confédération Nationale des Associations d’Installateurs et de Fluides (CONAIF). Too low a pressure hinders the proper circulation of hot water, leaving radiators lukewarm and the boiler potentially going into a safety mode.
When a radiator is hot at the bottom but cold at the top, or when you hear gurgling noises, trapped air is often the culprit. “Bleeding the radiators is a fundamental task for the proper functioning of a heating installation, because the presence of air can affect efficiency and raise energy consumption,” notes Mario Rial Axpe, head of the technical department of CONAIF. He advises turning off the heating, gently opening the bleed valve, and waiting for the air to escape. “You should keep the valve open until water comes out steadily; that is how you know the intervention was performed correctly. In this way, the radiator expels the air it contains,” adds the CONAIF spokesperson, before reminding readers to recheck the pressure on the gauge afterward.
Thermostat, Temperature, and Safety: The Final Steps for Optimal Heating
Once the boiler and radiators are adjusted, the specialists urge you to look at the room thermostat. It should be placed away from heat sources or drafts to avoid skewing the reading and triggering the boiler too often. For comfort, they recommend a target temperature of around 21 °C; every extra degree can add roughly 7% to the bill.
They also highlight the value of thermostatic radiator valves and programmable thermostats, which tailor warmth to each room and time of day and, according to cited studies, yield energy savings of about 8 to 13%. Safety is equally important: clear ventilation openings, a potential carbon monoxide detector, and seeking professional help if the pressure frequently drops or if some radiators stay cold.
