Do you mean an in-line tankless water heater for your kitchen sink; if so, I've heard there is a delay for hot water and the water temp cannot be set as hot as from a tank.

There is an option for an appliance version used primarily for tea and/or instant coffee which seems like a waste of space and money.

Both of the above are expensive at the outset and potentially costly to maintain.

Focus on quality for items you know you'll use rather than falling for a costly fad.

If you frequently run out of hot water, you might consider getting a larger water heater for your entire home or adding a second one specifically only for your kitchen.

I rarely use my instant hot water faucet. I suppose if you drink a lot of tea it might be useful.

I have an instant hot water and while I used at the beginning for tea or whenever I needed it, I stopped after I got an espresso machine that is connected to the waterline. If you make tea often, that would be useful

I loved mine. We moved recently, and I really miss it! Used it for tea, French press, pots of hot water (boiled SO much faster!), cleaning, and more. We tested our energy use prior to and during use, and found it used very little energy.

I had one in my last house and used it all the time. I liked it for tea but also for using on the bottom of pans with food baked on. A little hot water and soap, let it soak for a few mins and everything came clean easier.

I have had one for about a year - I love it. Useful for tea, french press, head start on getting pasta water boiling, cleaning.

We had one growing up, and my mom loved it. I've always wondered if they're not extravagent energy users -- like having another small water heater! Might be better to have one of those always-warm electric water kettles instead.

They might be good for instant coffee or tea. They aren't hot enough for really good tea. An electric kettle is much better.