ᐅ Which tankless water heater is suitable for the kitchen sink?

Created on: 14 Jan 2025 14:11
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LostWolf
Since I want to avoid a circulation line and the heat pump is located quite far from the kitchen, I would like to use a tankless water heater for the sink.

What power rating should this have for a basic kitchen sink?
Are there any general considerations to keep in mind when choosing a tankless water heater?

The installation will take place directly below the kitchen in the basement, so the pipe length will be a maximum of 2m (6.5 feet).
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LostWolf
15 Jan 2025 08:47
I should check to find out how much water pressure is available. I was thinking of around 5 liters per minute (liters/min) (about 1.3 gallons per minute) for a sink (good thing I asked here).

What would you do with the 11 meters (about 36 feet)? Connect it to the heat pump, or use a tankless water heater? (Or is there an option to install a small one in between? [the flow restrictor would need to be removable])
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nordanney
15 Jan 2025 09:17
LostWolf schrieb:

I would need to check how much water pressure is available.
For a sink, I thought more like 5 liters/min (good thing I asked here).

Usually, it's 3-4 bar (45-60 psi). Not too low, so there's enough pressure in the shower if needed.
You should ask the plumber who designed the system.
LostWolf schrieb:

What would you do here with 11 meters (36 feet)?

A heat pump and no instantaneous water heater, unless you need hot water very frequently. So, washing pans occasionally by hand, and the rest goes into the dishwasher.
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LostWolf
15 Jan 2025 09:21
Yes, exactly, only rarely for rinsing.

Dishwashers are typically connected to cold water, at least that's what I thought.
I only know a few models that have a separate hot water connection.
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nordanney
15 Jan 2025 09:36
LostWolf schrieb:

Dishwashers are usually connected to cold water, at least that's what I thought.
That's how I understand it too. Put everything you can in the dishwasher. For everything else, use the hot water connection. That way, you can also wait a few seconds if needed.
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wiltshire
15 Jan 2025 11:01
We have a solution using tankless water heaters and a hot water heat pump.
The main reason is that the two children’s apartments are only used sporadically over time, and I did not want hot water to remain standing in long pipes for extended periods. Another reason was that in our previous house, it was annoying to wait for hot water, and I wanted to eliminate this issue for the children as well.
With frequent use, connecting to the hot water heat pump is more cost-efficient.
We each use a 17 kW Stiebel Eltron unit. Since the electricity provider does not allow two tankless water heaters on one main connection, we have two separate connections and meters. This also incurs additional costs.
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LostWolf
15 Jan 2025 13:20
In your case, significantly longer pipes if these are separate apartments, right? So no tankless water heater after the hot water connection of the heat pump either, correct?