- 1). Turn closed radiators all the way to the open position. Radiator inlet valves that are only partly open can make a clanging noise. If a radiator remains cold at the top but is warm at the bottom, there could be air trapped inside. When this happens, steam can't get in, and the radiator won't heat properly.
- 2). Clean the air vent on each radiator. A clogged air vent can also prevent a radiator from heating up. Close the shutoff valve located at the bottom of the radiator before unscrewing the air vent. Unclog the vent by soaking it in vinegar.
- 3). Bleed air out of hot water radiators at least twice throughout the heating season. Locate the valve at the top end of the radiator. Place the radiator key in the valve stem and turn it counterclockwise until you begin to hear a hissing sound. Turning the key about half way will usually do the job. Close the valve again by turning the key clockwise as soon as water begins to drain out. Turn valve stems that are slotted rather than square using a flathead screwdriver instead of radiator key.
- 4). Check to see if the radiator valve might be blocked if you still get no heat. This can happen if the heating system has been turned off for an extended period of time. Mineral deposits from the water can cause the valve pin to stick. Push the pin sticking out from the radiator valve in and out. If the pin does not move, use your finger to thump on the side of the valve and then gently push down on the pin. Do this until the pin loosens. The pin should spring back out when pushed in.
- 5). Shim any radiators that are not slightly pitched toward the inlet pipe that comes up from the floor. In some homes, the pipe comes out of the wall. Place a ¼-inch shim under the feet at the vent end of the radiator. As the years pass, expansion and contraction can cause the legs of a radiator to dig into the floor changing the slope.
- 6). Inspect for any signs of water leaking around the inlet valve. Tighten the cap nuts located on the valve. Hold the valve with one wrench while you tighten each cap nut using another wrench.
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