While many newer homes today are built with a forced air heating system, meaning that warm air is pushed or forced through the ductwork and vents of the home, some homes still have steam radiators. These work with warm water that circulates through a system of pipes which then heat a surrounding space. Maintaining a radiator is not like maintaining a furnace since the unit involves steam and water, not simply air. Note a few tips for keeping your radiator in good condition if you've never had to maintain one before.
Bleeding radiators of excess air can keep them operating properly and avoid potential damage from that pressure. When radiators have too much air trapped in them, they may actually become cold, as the air might cool the water circulating through the unit. Most radiators will have a bleed vent in the back; this is held closed with a simple screw. Turn down the thermostat so that the water stops flowing and be ready for a bit of steam when you open the vent, so keep your face away from it. You'll notice some sputtering when you open the vent and when this stops, the radiator is bled properly and you can close the vent and adjust your thermostat again.
Leaks sometimes form even in the strongest radiator and even if you bleed the vents properly. It's good to inspect your radiator every month during wintertime or at least once before the start of the cold season. Turn up the thermostat so water is flowing through the radiator and inspect it on all sides for any type of trickling steam, which usually means a leak. You can patch small leaks with a patching compound meant for the material of your radiator in particular, i.e., steel or aluminum. Be sure you first clean the area and remove any paint or other materials, and turn down the thermostat so the metal is safe to work with.
Since the radiator works by circulating water, you want to ensure its slope is always right for the type of radiator you have. The owner's manual can tell you the right slope and angel for the radiator; if you hear hissing or bumping as it operates, chances are the slope has been affected; this might be by warped floorboards, loose connectors, or just your home settling. Check this slope every season and prop up the radiator on one side if needed to keep it at a correct angle.