Our furnace would click and click over and over before it would ignite. That scared us and you could smell gas sometimes in the basement.
Fearing the worst I called Deerfoot Mechanical. They sent a fellow out within 2 hours to have a look. The ignition was dirty and so it tried to ignite the gas but could not. He cleaned it and it worked great after that.
It was efficient and fast and worked the firs time.