I don't know about technical or code restrictions but I will say anecdotally, that mine occasionally drips after use. Secondly if you want to fill something larger than a cup will there be sufficient clearance to get it out without spilling?. Or if you need to a fill a jug or a pot with hot water, same thing. Having the sink allows you to do that. I often start off my soups or pasta with a large pot. I also use mine for soaking baking, dishes, pans, plates etc with boiling hot water. Seems to me, you may be limiting yourself for the ability to have it multifunctional. It's less of a big deal to fill a cup birth boiling water and carry it a few feet to point of use, ( you will be doing that anyway ) than carrying heavier larger receptacles to where you need them even if you will be able to have the headroom.

What about if you need to run it for a bit you haven't used it in a few weeks ( if you go away).

Consider how you will install the heater/storage in the cabinet underneath the counter. Also, your refrigerator water supply has a small reservoir that allows drips to accumulate and evaporate. You won't have a reservoir on the countertop and will find yourself wiping it away. Small issue, but it may come to bother you.

I had one of these in my last home. It came with the house. I ended up turning it off. It was an energy hog. I also had to worry about an additional water line leaking. Every year there are untold numbers of insurance claims due to the water lines to ice makers and water dispensers breaking or leaking. I'm not a proponent of hot water dispensers or pot fillers over stoves. They are needless expenditures and risks that I would prefer to avoid.

Last, these little water heaters tend to break with some frequency. Hopefully, you will get better performance than others.

Hot water dispenser came with the house -- thought it was the dumbest thing ever (well, maybe not ever...) but blow me down I ended up loving the thing and use it daily. It's great to jump-start boiling small amounts of water, using with stock base, cup of tea, etc. Agree with above re: filling jugs/larger pots and the occasional drips. So yea, best at the sink.

I second (third? fourth?) agree - at the sink installation is best. And yes, it is an energy hog. Turn the temp control down to the lowest setting that works for you.

We swapped out a filtered water dispenser for the hot water dispenser. I do use it quite a bit to save time. But I wouldn't call it an indispensable appliance for us.

^^ Mine comes out steaming hot and makes decent tea.

I guess I'm blind, too, because I don't know what steam looks like {shrug}.

@mxk3 z5b_MI - while JuneKnow wrote something very abrasive, the fact is that hot water dispensers do not dispense boiling water. Most teas need boiling water to steep properly (green tea being an exception). Steam will appear simply when the water is a certain amount hotter than the ambient temperature - you'll see steam coming off of lakes and rivers on cold winter days. Having said that, many people enjoy tea from their hot water dispensers, and don't care whether the water is boiling or not.

I am not a fan of hot water dispensers because every one I have ever had has broken due to our water being the slightest bit hard - not really hard mind you, just enough to break the darn hot water dispenser.

I drink a lot of of tea on a daily basis. Usually 4+ cups. Are instant hot water heaters more of an energy hog then frequently running an electric kettle? I tend to heat my water to around 170 degrees (which is blasphemy, I know!) and I am pretty excited about the adjustable temperature functions.

I never said it was boiling, I said it was steaming hot. I'm not a tea connoisseur, it's fine for me. Bouillon base dissolves quickly in it, and it jump starts boiling water in a pot. Just sharing my input. I love my HWD and am glad I have it. Don't care that it's an energy hog, I like the convenience of instant VERY HOT hot water. I think just about the only thing none of us disagree on is that it should be installed at the sink. So there's your answer, OP -- at the sink.