The bracha of sheheheyanu is recited on mitzvos that come from time to time (e.g., sukkah, shofar, yom tov). Why is this bracha not said when making an eruiv tavshilin?
This is a good question. The sefer Birkas Hazeman (R’ Shiloni) gives a few answers. Among them is, that according to the Maharshal we don’t say shehechiyanu on a mitzvah that doesn’t have a Birkas hamitzvos. Being that we don’t make a bracha on performing the mitzvah of simchas yom tov, so we don’t say a shechiyanu on the preparation for it.
In the sefer Hochi Itamar (R’ Itamar Tep) brings from Shut Siach Yitzchok 102 two answers.
- We don’t say shehechiyanu on a mitzvah that is only a hechsher mitzvah to another mitzvah.
- One of the reasons we don’t say shehechiyanu on hallel is because we don’t say shehechiyanu on a mitzva that sometimes comes at intervals closer than thirty days, since part of the time we wouldn’t say the bracha so “lo plug”. Here too it is possible to make an eruv tavshilin more than once a month, For example, when Rosh Hashana is on a Thursday, we will make an eruv tavshilin for Rosh Hashana, for the first days of Succos and for the last days!