Have you notified the landlord of the problem? Have they refused to fix it?

Furnaces should not be that loud, and there may be a problem with the fan motor.

How long have you lived there? First cold spell is my guess.

Notify the landlord asap. He will either thank you for alerting him to a problem or come listen and tell you that is what every furnace sounds like.

If nothing is wrong with the furnace. Laws vary from state to state, but my guess is you would lose if you broke the lease. You knew the furnace was in the living room before you signed the lease.

Thanks for your replies, we are talking with the landlord this week......our problem is we didn't see this apt. before we moved in, we looked at the one above it which the furnace was in the front hall......these are all new furnaces they put in this early summer.....not the same ones when we looked at the apts.
It is just hard to beleive they would face the front of the furnace to face right into the living room for you to hear that explosion when it lights.
Thanks again for your input :-)