You do have a potential cause of action for fraudulent inducement.  You could therefore sue the seller for the replacement cost of the furnace.  This is a claim recognized in Pennsylvania.  However, a couple of things could affect the success of your claim.  The first is any documents that you signed.  If you signed any document after the representations by the brother that no representations were made regarding the integrity of any items on the property, then your claim could be rejected or limited.  The second issue that you have is who did the misrepresenting.  To pursue a fraudulent inducement, you need to show that the seller did something.  Since the brother made the statements, you'll need to show that the brother was acting on the seller's behalf.   You may even need to loop him in as a party depending on exactly how everything was represented.  If you're not sure about what the documents you signed mean or the effect they will have on your case, you should arrange with a basic consulation with an attorney first-- so they can give you advise more tailored to how your contract reads. From there, you can make a better decision on whether to file or not.