Use a Tankless Water Heater on Yom Tov

[Travel Lover]

While trying to figure out how to make a tankless water heater permissible to use Yomtov, I found this from the StarK to be very helpful. So posting here, I believe many people that have tankless water heaters might not even be aware of all this serious issues this can involve without the proper setup.

"Thankfully, there is a rather simple solution for this issue: installing a recirculation line with a circulation pump. This recirculation line goes throughout the house and creates a loop where water is constantly flowing around and around through the tankless water heater (thereby keeping the flow sensor always working). Whenever it detects that the water temperature
in the recirculation line drops below the desired hot water setting, only then does the fan and gas burner kick on and heat the water back up to the desired
temperature. This ensures that there is always hot water at, or near, your water faucets, thereby enabling you to access hot water quickly and efficiently."

[Travel Lover]

Would be helpful to hear from people, their experience with the "recirculation pump" method.

[aygart]

This looks like it would make the tankless less energy efficient than the worst tank water heater.

[Alexsei]

You need a dedicated return line at the farthest point in your home, other option is to reroute lukewarm water back to the cold line.

But this would introduce its own shabbos challenges

https://jmpcoblog.com/hvac-blog/domestic-hot-water-recirculation-part-5-recirculation-without-a-return-line

[Travel Lover]

This looks like it would make the tankless less energy efficient than the worst tank water heater.

Its meant to be used with a switch that turns the pump on only for Yomtov

[Alexsei]

This looks like it would make the tankless less energy efficient than the worst tank water heater.

Not sure, but likely cancel out any potential savings. The question is if OP prefers tankless for energy savings or for an entirely different reason.

If OP already has a tankless heater installed and they want to solve shabbos/Yom tov issues it can be a plan, or of they need tankless due to space constraints

[Alexsei]

Its meant to be used with a switch that turns the pump on only for Yomtov

There's huge benefits for comfort if you have a large home.

But for yomtov only they can pair this with Melacha plug @Yo ssi

As long as it's a manual process it's not going to be stealth Yom tov mode.

[Travel Lover]

This looks like it would make the tankless less energy efficient than the worst tank water heater.

Are there any other solutions you're aware off? other then just don't use hot water on Yomtov...

Really like to hear from people that have this already what it is like

[Alexsei]

Are there any other solutions you're aware off? other then just don't use hot water on Yomtov...

Really like to hear from people that have this already what it is like

Why did you choose tankless over tank in first place?

[Travel Lover]

Why did you choose tankless over tank in first place?

I don't yet have one.

Due to some construction in my home, I'll need to update to a direct vented heater. so decided to look into this, only to learn that it has issues on YomTov.

But I do wanna try to make this work, since it appears to be much more energy efficient.

[Dave321]

Ok I have a tankless just for my master bath. What we did is create a bypass for YT. So erev I would shut the valve around the tankless and turn on the valve to take water from my 75 gallon tank that we use for rest of the house.

[MoYS]

Ok I have a tankless just for my master bath. What we did is create a bypass for YT. So erev I would shut the valve around the tankless and turn on the valve to take water from my 75 gallon tank that we use for rest of the house.

Same here, I just purchased a home with tankless. I was advised to add a boiler and manually shut / open the valves. But have yet to move in and try.

[Travel Lover]

Same here, I just purchased a home with tankless. I was advised to add a boiler and manually shut / open the valves. But have yet to move in and try.

Is it easier/cheaper to add a new boiler, then add a circulation pump?

[Alexsei]

Is it easier/cheaper to add a new boiler, then add a circulation pump?

Do you have open walls or an easy enough path for a return line ?
Unless you want to just install the pump without a far away return line and skip the comfort benefits?
Would connecting the pump return line locally next to the heater solve shabbos issues ?

[MoYS]

Is it easier/cheaper to add a new boiler, then add a circulation pump?

He didn't mention the recirculation pump, but just from the way he was talking I would guess it would be more expensive. He said it was no big deal to add the boiler.

[yoruel]

[yoruel]

Someone in Baltimore worked this out with a hechesher

[Alexsei]

https://www.amnon18.com/

[Travel Lover]

https://www.amnon18.com/

Someone in Baltimore worked this out with a hechesher

Wow this is so revolutionary!

[aygart]

https://www.amnon18.com/

3] The last issue is that of the digital sensors and the digital display. Attached to the hot water tank is the Amnon 18 device which has a digital display screen conveying the current temperature of the hot water tank. As one uses 'hot' water, cold water rushes into the tank and slowly starts to cool down the water inside. After some time, this change in temperature will display on the screen. Additionally, the electronic sensors themselves calculate the water temperature by means of slight changes in voltage. Therefore, it's possible that every time the hot water tap is opened, one is affecting the display, as well as the workings of the sensor.

However, as explained at length in the article, these changes do not occur immediately and are classified as 'Grama'. Since one does not intend for any of these changes, it is considered 'Psik reishe' with a grama and is permitted, along with other considerations. [Additionally, there is an option on the device called 'Magen Avraham'. Choosing this option means that as long as the fire or heating element is on, the 'mashgiach valve' is closed and one can not take hot water. During the time when the fire is off and one is able to take hot water, the display will not show the temperature. Rather, it will just display the word "standby", thereby avoiding any question of affecting the display.]

Interestingly, this item is not addressed in any of the letters displayed