7 Pa. Code § 59a.328
Hotwells must be enclosed or covered and equipped with indicating thermometers either in the hotwell or in the hot milk inlet line to the hotwell and if used for holding high heat products must also have recorders.
This section cited in 7 Pa. Code § 59a.304 (relating to equipment and utensils); and 7 Pa. Code § 59a.326 (relating to equipment and utensils).