[Avodah] Modern Shabbos Urns

[Akiva Miller]

.
When I was younger, the electric urns that we used for hot water on Shabbos
were very simple: fill it, plug it in, and there was a valve for taking
the water when you needed it. But many of the newer ones have various
settings. Mine (
https://www.amazon.com/ProChef-SM300-35-Cup-Water-Shabbostat/dp/B07FK8KTZ6)
for example, has three settings, called Regular, Shabbat, and Yom Tov.

The manual gives the following explanation of the three settings:

> Regular Mode: Keeps the water hot based on the water temperature
> Shabbat Mode: Keeps the water hot based on a timer
> Yom Tov Mode: Keeps the water hot based on a timer and is Halachically
permissible to add cold water on Yom Tov

Based on that explanation, this is my understanding: In Regular Mode, the
thermostat is in full control; when the water gets too cool the heater will
turn on until the correct temperature is reached, and then the heater turns
off. In Shabbat and Yom Tov modes, the thermostat never responds to the
water being too cool. Rather, every so often the timer will turn the heater
on, and the thermostat will turn the heater off when the water is hot
enough.

So what's the difference between Shabbat Mode and Yom Tov mode?
If I would use the Shabbat Mode on Yov Tov, is it assur to add water?
If I would use the Yom Tov Mode on Shabbat, is there a problem?

These are not theoretical questions. If we are still in Chutz Laaretz for
this coming Pesach, we'll have a "three day yom tov", and I don't know
which setting is preferable. Does anyone else know?

Thank you!
Akiva Miller
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.aishdas.org/pipermail/avodah-aishdas.org/attachments/20200328/71649e8d/attachment.html>