Hi,

For the past two days, I've been noticing a really loud 'boom' or 'thud' coming from the general area of the furnace. It is a gas furnace, and it has been extremely cold for the past two weeks. I think the past two days are probably the first few times it has shut down and restarted, as it was running pretty constantly to keep up with the cold before. The thermostat is set at about 68. Is there something I should do here? What would cause this? It sounds like something that might occur as it fires up, but it's very alarming!

Thanks!
Jean