According to this website once installed one may use hot water on Shabbat without violating Halacha.
They have Rabinnic endorsements from the following Rabbanim.
Karlsburger Bais Din - R. Chezkel Roth
Vaad Hakashrus Meged Yehudah
Congregtion Nitei Gavriel R. G. Zinner
Rabbi Abraham Blumenkrantz
Rabbi E. Fisher - Head of Gur Kolel, Brooklyn
Was wondering if anyone has any first-hand experience with them and how they performed in terms of:
- The time length which it has worked for them without any malfunction (if any).
- Any Halachic concerns encountered while using the product(ie-The consistency in the water staying heated as advertised,is this more of an emergency type product than for common weekly use)
- Any difficulties encountered while getting the product installed as well as maintaining the product.