12 Best Under Sink Water Heater (2023 Updated)

The “Min” “Ideal” and “Max” temperature settings on the unit appear deliberately misleading and contrary and confusing. Temperature, after all, is a NUMERICAL setting. A -numerically range- (even) would have been in the least a bit more appropriate than ‘Min”, “Ideal” and “Max” which describes NOTHING! I have been disappointed with this unit!.

Had it installed in less than an hour under my kitchen sink. It provides instant hot water instead of waiting over a minute for the hot water to get to the sink from the house hot water supply.

I have an enclosed trailer, that I’ve turned into a toy hauler. I camp in it, and haul my Harleys in it. I needed a little hot water heater for my sink. This thing is great! Fits under the sink, out of the way and keeps the water hot, when you need it.

I’ve only been camping with it for a week now,but so far it does what I needed it to!.

I had some doubts about the efficiency of these tankless units and I must say this thing is amazing in all aspects. We have 6 people in my house and this is the best upgrade I could’ve ever done for cost savings.

My electric bill went down $100 consistently and I’ve only filled my 250 gallon propane tank (to about 80%) one time since January. I would recommend anyone get a Rinnai tankless water heater. Quality seems excellent and I have seen no issues after 8 months.

I love this system. Our previous water heater was getting ready to go so I did some research on tankless heaters and found the Rinnai tankless heater was a good fit for our house as it had good ratings.

I installed it myself as I have the experience to do so. I love this water heater. We have a Jacuzzi tub and never run out of hot water. Our propane bill has gone down. I would highly recommend this to anyone.

This water heater was a replacement for my existing Rinnai tankless heater which lasted 18 years. We were very happy with the old unit, and seem to love all the features of the new unit The old heater’s heat exchanger started leaking due to acidic water at the house, and tried it’s best to make hot water in spite of water leaking all over the enclosed electronics.

All in all a great product. I anticipate the new heater will last as long or longer.

We install a ton of tankless heaters (various manufactures) and have installed approximately 25-30 of this model with built-in recirc. They started our great but then we quickly realized there IS a known doucmented issue with these that has caused Rheem to have Repair kits especially for error code 67 (air gas mixer).

We have spent approx $10k swapping out parts & complete heater swaps. yet, rheem and local suppliers keep selling them! All other Rheem products are great. Not this one!.

The only issue I’ve encountered is that with todays low flow fixtures the heater will not always activate. It trys and then eventually gives up. I have to open another fixture on the first floor to get hot water on the second.

I have plenty of pressure just not enough flow.

For 3 years since purchasing our home weve had to wait way too long for hot dish water and even then it was not very hot. Our water heater is quite a distance from the kitchen. After installing the Bosch ES2.

5 we have very hot water almost instantly. The 2. 5 gallon size is perfect for my wife and I. I had researched tankless units which typically require 220W service. The convenience of just adding a plug adapter to our disposal/ dishwasher receptacle was nice.

If you are fairly handy you can DIY this; it may require some modification to the drain pipes under the sink to fit and you will need to purchase and install some flex water line to connect to your existing water valve.

It is preferable to run the pressure release valve outside so once again, some parts and installation are required. We ran our current hot water line into the unit and out to the faucet and the result is super hot water right away.

I would highly recommend this product for a simple solution to a large problem.

This is the 5th unit I have purchased and it does everything I wanted an under sink heater. I have a tankless hot water heater and it work very well except that the water runs from heater to sink plus the tankless water heat up time does not allow to wash your hands in hot water.

Therefore the 5 Bosch ES2. 5 Electric Mini-Tank Water Heater Tronic 3000 T 2. 5-Gal heaters we have purchased. The heater works well and we did not see any spike in electric usage that we thought we would have even with having 4 units installed at once.

This 5th unit is going in as we added a bathroom to the 3rd floor “game room” area.

The heater arrived quickly and in good condition. It installed easily under our bathroom sink. The biggest challenge was to find a pan of suitable size to put under the heater as is recommended in case of leaks.

Found a 16″ x 16″ x 2″ aluminum cake pan that seems will work for minors leaks. I connected the inlet to our “hot” water line which use to deliver warm water to the facet after 1-2 minutes. With the heater installed, there is warm water in about 2 seconds.

I set the thermostat to “ideal” which is in the middle of the setting range. Right after the heating light goes out (takes about 10 minutes to reheat the tank) the water is very warm, but not hot. After using the water for a 1-2 minutes, it begins to cool down because new cold water is flowing into the heater.

The light comes on, and 10 minutes later the water is very warm again. Works well for our evening get-ready-for-bed routine. The only slight issue, and the reason for 4 instead of 5 stars, is that the water has a bit of an odor.

It is not as noticeable if the water was just reheated, but if the water has been sitting in the heater overnight, there is a bit of an odor. Maybe it is just new (but not good) smell that will eventually go away.

After using it for about two weeks, it seems to be a great little unit, and one we wish we had purchased years ago. Only time will tell how long the unit will last, but I plan to replace the anode rod each year as recommended.

Everything as advertised, Works great for my off-grid cabin running on solar power. Enough kitchen sink water to do dishes and general clean-up. Heats water in about 30 minutes.

This unit works great, and provides enough hot water to take a shower – if you use very little water, and turn it off when shampooing / conditioning your hair. It’s a great way to save water! The recovery time is decent, and the water does get very hot (if you set the temp high).

Easy install. Works great. Used in an office setting where hot water for hand washing is the only need.

Should have done this a lot sooner. Now instead of having to deal with cold water at the kitchen sink for over a minute, we have nice hot water in 2-3 seconds. Got all of the parts (Sharkbite elbows and ball valves, along with a set of 1/2″ FIP supply lines) here at Supply House except for a 2′ piece of PEX I purchased locally.

Most of the work for this project was running the dedicated circuit up from the basement in the sink cabinet. Even that wasn’t that tough. Supply House has become my good to place for DIY plumbing and HVAC needs.

This is the primary water heater in my camper. Since it draws so little electric, it works quite well without taxing the power supply of 30 Amps. keeps the water hot and on demand when needed and with the addition of a remote switch, can be turned off when not required.

And, it fit under the counter in the kitchen saving a lot of additional plumbing. Can’t go wrong with this if you need auxiliary water or point of use. Oh, and it got here exactly when they said it would.

Thanks again.

Product was well packed. Installation instructions included in box. Arrived on time. Simple to install. Excellent operation. Heats very well and holds heat well. I recommend purchasing this unit. I intend to purchase another unit.

Ratings are locked on No but I give 5.

I bought a returned/refurbished unit. Checked it out before doing the full install and it worked. Its been 3 weeks now since its been in use and it works great. Water gets so hot you dont want your hand in it when set on high.

Heats up quick after use. 1 problem: The 1/2 npt threads on the inlet and outlet had flat threads with bad form. Had to use a lot of Teflon tape and pipe dope. Other than that its an excellent product.

I installed it in my bathroom sink that is the furthest room from the hot water tank in the basement. It takes 3 gallons of wasted water for it to be hot so needless to say I never have hot water in my sink, until now.

I am so thrilled to have hot water in less than 2 seconds. Awesome! Now everyone else in the house wants one!.

We have a kitchen sink that is very far from the water heater in our home. It would take 2 to 3 minutes to purge the hot water line before hot water finally arrived. I added the Bosch Tronic 3000 US7.

Wow! It is not difficult to install. It does require a 30 amp circuit which may require licensed installation. The water hook up is very easy. I installed this unit in the basement ceiling directly under the kitchen sink.

This allowed for more room for the installation. We have 120 F degree water in 5 seconds. My wife is very pleased that now when she requires hot water it is instantly available. The unit is designed to provide water for one sink only.

It is a great product and I recommend it to anyone who needs instant hot water.

I am using this unit as a single point of use in my shop sink. Easy to install and hook up. I put in a valve on the hot water side thinking I may have to restrict the flow to obtain the temperature I wanted but it was no problem, am running it full flow and have to add a little cool water to temper it down.

Well satisfied!.

there was no description of the use of this heater. I wanted a tankless heater for my small house and this for under the sink, which is not enough hot water. thanks

Scratches and DENTS??? NO WAY!!! USED??? Didn’t look so. Came packed and wrapped new! Couldn’t see how it could have been ‘used’. HOWEVER. The thermostat has a wide differential, and can’t be changed.

I love it. Beautifully designed! Great deal!!!!.

When they say “used”, they ai’t lyin’. Unit is operating properly after much hassle and cleanup. It had plumbing dope smeared all-over with hand-goo, etc. These have rubber inserts to hold-in what they call “pipes” in the cold and hot-water line inlets.

The rubber is too thick to install normally, so you must find a different way, or they will not install.

I ordered the wrong unit. but I will be back to get the right one ! And a couple more. Your ordering, shipping and return process are all EXCELLENT. Eemax tech support is also excellent. I cannot wait to get my new tiny bathroom up and running.

I will keep you updated.

I replaced a 50 gal. water heater with this tankless water heater. I must say I was reluctant at first before I even order it. I have put a few of these heater before years ago that claimed it would give plenty water only keep in mind was 25 – 30 years ago they never work as advertised.

So I talk to people who had these heaters, I done other research on internet. So I order and installed it must say my wife I have used it washing clothes, dish washer. Shower, bathtub many item at same time No trouble at all.

Looking for the difference in my power bill.

This was a very smart decision to install the on demand hot water heater. I bought the 5 GPM heater which is enough for the two of us. I live in the northeast in a cape style house with about 1400 square feet.

I suggest if your house is over 2000 square feet, I would go with a bigger output demand heater. It has reduced my monthly electric bill about $45-$50 and should recoup the money for the heater and electrician in about 18 months.

The savings will depend on your hot water usage and the temperature of the output water. My old electric water temp output was 127 degrees and the on demand is only 113 degrees. I barely use any cold water while taking a shower so there is also a savings on your water bill.

The installation of the heater is pretty simple if you have some plumbing knowledge. I do recommend to use a licensed electrician unless you are very knowledgeable about wiring. I wish I did install the on demand heater years ago.

Allan in Connecticut.

The unit was fairly easy to install and re-plumb from existing water lines. The electrical was more extensive because new wiring had to be run, again not difficult if you have experience. if not hire an electrician.

The pressure drop across the unit was a little more than expected. I think operation of the unit will be easier in the summer when the incoming water will be warmer and delta T will be less. I have single lever fixtures in my showers and adjusting the temp is a bit tricky because turning the handle modulates both hot and cold water making even temperature difficult.

This is getting easier with time.

We have three of these model 180 heaters now. The oldest two are 7 years old and still work great. Saves about $25 per month on the electric bill depending on usage over our old electric tank heaters.

I will say most showers and bath tubs flow water to fast when wide open for full heat. My water is 55* at heater intake and comes out 122* at the shower head as long as i only open the shower 90%-95% which considering the $$$$$ savings every month I will continue using, buying, and recommending these heaters!!!!!!! They pay for themselves in the first year!!!!!!.