Many older homes still have furnaces with pilots that burn around the clock to fire up when heat is needed. Newer models don't have a pilot light. Instead, they use spark igniters that only come on when burners need to light and then turn off until needed again. If the heat won't come on, it may be the igniter and you'll need to test it. Sound risky? It's easy. Look where the pilot used to be. You'll see two wires, disconnect them and test the igniter terminals with an ohmmeter. A reading between 50 and 100 ohms is normal. If it's way off, it may be time to replace it with a new auto pilot igniter.