If one rents a vacation house and wants to Kasher the sinks and counters for Pesach, if it is unknown weather or not anybody used the rental within the last 24 hours can one apply the principle of “stam kli eino ben yoma” and kasher in a regular format without waiting?
If the principle isn’t applicable, can one just put some bleach in the electric water kettle they are kashering with to make any potential (safek ben yoma) non-kosher tam – pagum from the bleach?
Under normal circumstances we say “stam kli eino ben yoma” and you can assume that it was indeed not used for the last 24 hours. If you know that the sinks and counters were indeed used for hot chometz within the last 24 hours, if you cannot wait until after 24 hours, you can add bleach to the kettle and kasher that way.
As a side point make sure you do the hagalah before the fifth hour on Erev Pesach, otherwise the hagalah will be difficult to do.
Chag kasher v’sameach
Minchas Shlomo 2 97(4-2), Shulchan Halevi 1 chap. 24-6, Chut Shani pg. 142. According to Kovetz Halachos (Pesach) 11-3, if you know that they are not ben yomo, hagalah should be done twice, once with bleach and then again without.