You may be able to, if the furnace and home office are in the same structure. The thing to remember is that you only get to claim a portion of the expense equal to the portion of space you are using in your home (if your home office is in your house). For instance, if your office is 100 sq. ft. and your house is 2000 sq. ft., you can claim only 5% of the expense. On top of this, you will have to schedule a depreciable value of the furnace over the expected course of it's life. After all this, it may be more hassle for you to try and claim the furnace for the minimal amount of gains you will receive.
