When kashering my sink for Pesach, is it preferable to use a Pesach kettle or a chometz one – provided I don’t have one set aside for kashering the sink?
Both kettles are fine to use, with a slight preference for the chametz one.
The reason for this is there might be a crumb of chametz left, and we say nitzok ke-chibbur for chametz (see Minchas Yitzchak 5:81; see also Darchei Teshuvah 105:97 and 99). However, this is a far-off concern, so that both kettles are fine.
There is no need to set aside a kettle for kashering the sink.