Good question Tony. The law changed last year regarding rentals. It used to say that you had to rent the ENTIRE property to lose the exemption. This year, the law states you cannot rent a substantial portion or "Substantially All" of the property. What that term means is open to interpretation by each of the 67 county property appraisers. Some may say 51% or more, or some may say 90% or more. Who knows. I have been trying to get a statutory definition of what the Legislature meant inserted into the statute to no avail...yet.
You can loan you home to someone (whatever you meant by that) but when there is a rental or lease contract involved, that is where the issue gets complicated.