Do you think theyre gone?

If I am understanding your question correctly.... You had fleas, treated the dog and sprayed the carpet and if the heat isn't on they won't come back?? Unfortunatly they don't need the heat on in the house to live. I think that the only way to ensure that the fleas are completely gone is to remove the dog and then use a "flea bomb" on the whole house. Fleas not only live on carpeting, but in bedding and furniture. While the dog is out of the house, I would have him treated again and then continue monthly with the Frontline. They are nasty little critters....good luck!