[Avodah] Can One Add Water To A Hot Water Urn on Yom Tov

[Micha Berger]

On Thu, Dec 01, 2022 at 06:18:25PM +1100, Joe Slater via Avodah wrote:
>> Rav Belsky explained that there are two heaters in an electric urn. The
>> larger heater turns on when the urn is filled with cold water. Once the
>> proper temperature is reached, the first heater turns off and a second
>> smaller heater turns on to maintain the temperature.

> Rav Belsky never saw my electric urn or he would no doubt have paskened
> differently. In fact every electric urn I have ever owned  (perhaps five or
> six, made by at least two different manufacturers) had but a single
> element, operated via a simple bimetallic thermostat. I suppose things may
> be different in the US where you use lower voltages, but I'm frankly
> surprised that a manufacturer would use such a complicated apparatus
> instead of the simple design I'm familiar with.

I would expect that regardless of the number of elements, there is a
"boil" and a "keep warm" level. Having a thermostat that trips the
whole thing altogether off will cause the water to cool quicker and
the full heat to go on more often. Having a "keep warm" is more fuel
efficient. And given the price of these things in Israel...

But I didn't write in to play engineer.

My LOR told me it is permitted to add water if you have an indicator when
the urn is boiling the water (or RJS's urn is on). Because then you
cann't trip the thermostat when you pour cold in -- it's on already.

Tir'u baTov!
-Micha

-- 
Micha Berger                 Education is not the filling of a bucket,
http://www.aishdas.org/asp   but the lighting of a fire.
Author: Widen Your Tent                   - W.B. Yeats
- https://amzn.to/2JRxnDF