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Internet #206393135

Model #ES 4

4 Gal. Mini-Tank Electric Water Heater

  • Floor or wall-mountable, perfect for under sink placement
  • Plugs into 120V outlet, 6-year warranty on glass lined tank
  • Same-day installation in most areas, call 1-855-400-2552 by noon
  • See More Details

Frequently Bought Together


Product Overview

The Bosch 4 Gal. Electric Water Heater has a 4 Gal. mini-tank that fits under your sink to provide hot water right where you need it. The heater plugs right into a 120-Volt outlet and has a lightweight, compact design that's easy to handle and install. A glass-lined tank offers great insulation, while the heater's fast recovery rate eliminates long waits for hot water. A temperature-and-pressure relief valve enhances your safety.
  • 4 Gal. mini-tank fits under your sink to provide hot water right where you need it
  • Electric water heater is easy to maintain
  • Fast recovery rate eliminates long waits for hot water
  • 2-year warranty on the parts, 6-years on the tank
  • 98% thermal efficiency
  • Glass-lined tank offers great insulation
  • Plugs into a 120-Volt outlet, 2.5 ft. cord for flexibility when installing
  • Installs independently or in-line with a large hot water source
  • Can be mounted on a wall
  • Temperature pressure relief valve
  • Return policy: 90 days
  • Click here to check out our buying guide on water heaters

  • Click here for more information on Electronic Recycling Programs
  • California residents

Info & Guides

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7 Gal. Electric Point-of-Use Water Heater
Name2.5 Gal. Electric Point-of-Use Water Heater4 Gal. Mini-Tank Electric Water Heater7 Gal. Electric Point-of-Use Water Heater
Water Heater ProfileCompactCompactCompact
Efficiency LevelSuper HighSuper HighSuper High
Water Heater FeaturesGlass-Lined Tank,Overheat Protection,Temperature Pressure Relief Valve,Wall MountedGlass-Lined Tank,Overheat Protection,Temperature Pressure Relief Valve,Wall MountedGlass-Lined Tank,Overheat Protection,Temperature Pressure Relief Valve,Wall Mounted
Fuel TypeElectricElectricElectric
Nominal Tank Capacity (gallons)247
Application TypePoint of UsePoint of UsePoint of Use
View ProductView ProductView Product



Product Depth (in.)
Product Height (in.)
Product Width (in.)
Tank Valve Size (in.)
Water Connection Size (in.)


Amperage (amps)
Application Type
Point of Use
Efficiency Level
Super High
Finish Family
Fuel Type
Household Size
Maximum Temperature (F)
Minimum Temperature (F)
Nominal Tank Capacity (gallons)
Pack Size
Product Weight (lb.)
Rated Tank Capacity (gallons)
Required Volt Connection
120 volt
Tank Lining Material
Tank Warranty
6 Year
Uniform Energy Factor
Water Heater Features
Glass-Lined Tank,Overheat Protection,Temperature Pressure Relief Valve,Wall Mounted
Water Heater Profile
Wattage (watts)

Warranty / Certifications

Certifications and Listings
CSA Listed,UL Listed
Labor Warranty
No Warranty
Part Warranty
2 Year

Questions & Answers


Does the unit constantly keep the water hot or does it heat it up when used? Looking at installi...

Asked by Manny April 15, 2021

It keeps the water hot but use it as an on demand heater. We have an light switch conveniently located under our sink. When we need hot water to wash dishes we flip it on. It takes about 10 minutes to heat up the tank.

How difficult is it to replace the anode?

Asked by Doug January 22, 2021

It’s relatively easy if you have good access to the front of the unit.

Can this heater be used for a whole water system of one Bathroom (that includes sink and shower a...

Asked by carlos January 16, 2021

Carlos, "Technically" yes. However, "practically" there are limitations that may suggest doing something different. Many customers find that they can get an adequate shower with this ES4 unit. This will be a much quicker shower than one may be accustom with a standard size tank. Plus, if the sink is also pulling from the tank at the same time, then the duration of the hot water shower will be reduced even further. You may want to look at stepping up to our model ES8 which has a 7.2 gal. reservoir vs. the ES4 at 4 gal. Another option for you is to consider using one of our tankless electric solutions that have no reservoir and never run out of water. For your application our model US12 will certainly work and our model US9-2R is an option if you are in a relatively warm climate (such that your ground water temperature is warmer tan say in Maine). The tankless electrics do require direct wiring and will have greater electrical needs in regards to the circuit's amperage and wiring. All that are mentioned here are available on this website.

how much power does this use per 24hr cycle

Asked by abe December 9, 2020

I have seen no change in electric bill for the past month since installation.

any problems on using with a well system

Asked by pkb December 6, 2020

That probably depends on your water quality. If you get sediment or have very hard water it would probably be smart to install a filter or water softener to protect the hot water heater (and all other appliances and valves in your house). Hope this helps!

If I connect this to one sink (in cabinet underneath), would it also supply water to other nearby...

Asked by JP5050 November 11, 2020

Entirely depends on how the piping runs from the outlet of this tank. If those pipes also feed the other sinks' hot water connections then yes, it will deliver heated water to them. If it is only connected to one sink then no, it will not "back feed" other sinks in the system.

Can this be installed outside? The Bosch 4 gal mini tank electric water. I had one under the sink...

Asked by Dex November 8, 2020

See my product review Feb 18 2021.

Can I install this unit upside down. As I want to frequently drain it when we leave a winter cabin

Asked by Camperdude October 20, 2020

The instruction manual does not show an upside-down installation diagram. Suggest you call Bosh and ask an 'application engineer' the question! Bosh Technology Corp. 866.642.3158 boshheatingandcooling.com. Good Luck!

How many amps does this unit need?

Asked by Tommy September 18, 2020

12 amps at 120 volts

Do you have someone to install it in my home. I have one that needs replacing so connections nee...

Asked by teemo August 31, 2020

You can hook up the old water lines to the new heater yourself. If your old hot water heater has a connection for the Emergency Release valve (I call it the pop-off valve) that is vented to the outside of your home, you can also hook this up yourself. If it doesn't, you will have to have a plumber install a line.

4 Gal. Mini-Tank Electric Water Heater - page 2

Customer Reviews

  • 4.5
    out of 486 reviews
  • 89% recommend this product
Filter by:
Showing 1-10 of 486 reviews
Easy to install and works great. I actually installed...
Easy to install and works great. I actually installed it in the crawl space directly under the kitchen sink. To facilitate servicing the unit and as a proactive way to bypass the unit in the event it fails, I installed valves on the in and out connections and a third valve to pass the master water heater water to the sink. Also have a slip connection on the relief valve pipe for removal.
by GEB
Junky product with a bad warranty
Most of the good reviews here were probably written too soon after purchase to really test this product. I purchased one of these and 2 years later it completely failed. It leaked inside the case, shorted the wiring and can not be repaired. I sent pictures of the unit to Bosch and they denied responsibility for the failure, claiming that I should have taken it apart every year and replaced all the parts that were failing. Which other company forces customers to disassemble appliances and do invasive maintenance themselves under threat of voiding the warranty if they don't? Most companies void the warranty if you open their appliances and have all sorts of warning stickers cautioning customers from opening their products. This is a junk product with a name brand on it that deceives people into thinking it's good. If you buy this product, make sure to plug it into some sort of protected outlet or cord with fuses or breakers and you should consider buying a 5 year warranty as you will probably need it.
by GCdG
17 people found this helpful
Bosch 4 Gallon Heater Works, But You Have TO Do the Maintenance!
I bought the water heater about two and a half years ago. Worked fine for about a year and 8 months, then started to leak early in the morning and damaged my wood floor. I took it back since it had a 6 year warranty, but I had to contact Bosch to get a replacement. Bosch stated that they would not replace it unless I could prove that the anode was still good. I took it apart and low and behold, the anode was completely used up. This being the case, the 6 year warranty was void since I did not change out the anode. However, Bosch did send me a new (discounted) one for $130. Bosch also told me that in some cases the anode can go bad in as little as six months if you have corrosive water. Well, I replaced the old water heater with the new one and made a note to check the anode at about 1 year; however, I decided that I better check it at the 8th month. I did, and found that the anode was also gone after only 8 months! Now I will start replacing it at 6 months since it appears that I have highly corrosive water. Lesson leaned is to change out the anode every 6 months not at 1 year as Bosch recommends. Also, changing out the anode (about $18) is time consuming since I have to drain it via a syphon and you have to clean out the tank because spent anode sits on the bottom. It is a good tank, but you must check the anode at least every six months to make sure the anode is OK, if you are not sure what the corrosivity of your water is. I assume this would be the case what ever brand heater you use.
by Jongello
16 people found this helpful
Very happy with this solution for my RV problem. I have an older RV we live in and don't travel ...
Very happy with this solution for my RV problem. I have an older RV we live in and don't travel with. The original water heater finally gave out with multiple corrosion holes. The cavity left by the 10 gal. gas/electric Atwood heater was large enough to accommodate this heater neatly. The height is a close call as the dimensions do not include the height of the relief valve on top. I called Bosch and spoke to an engineer that told me the valve is about 3 inches tall so that it was just short enough to fit. My own area had some extra height so the fit was good. I had to order some pex fittings to go from 1/2" pex to 1/2" mpt plus some braided hoses. I then cut out the existing RV valve setup and connected the heater up. I plugged it in and was good to go. I was not sure the heater came on at first as the mounting had bright sunlight and the on light was too dime to see at first. I shaded the light with my hand and was then able to see it was lit. This would not be an issue with a normal indoor installation. I then bought a scroll saw from Home Depot and a 32tpi metal blade and cut the outer door panel off of the "dead" old heater and installed it back on the RV for a clean finish to the installation. From the outside you would never know of the surgery. Although it is only 4 gallons I have not run out of hot water with back to back showers or dishes. I set the temperature to halfway between normal and max and with the lower flow rate of the RV we just use more cold water to adjust the temperature and all is well. This was a great solution and saved me over $500 compared to a replacement RV heater. This heater also appears to better insulated as well with foamed in place insulation like a picnic cooler.
by CactusPete
2 people found this helpful
I was shipped a RETURNED item, not happy. I am returning this and ordering another one - hopefull...
I was shipped a RETURNED item, not happy. I am returning this and ordering another one - hopefully it is NEW, unopened, unused, un-returned. I noticed the box had been re-stapled before I opened it. Also checked the bottom and it was re-stapled. I opened the box and both pieces of styrofoam shipping were stack on top of each other instead of one on bottom one on top. Also, the user manual was crumpled - shoved back in there. Also a cap on one of the nipples wasn't screwed on straight - easy to tell the item had been opened. I didn't even take it out of the box. Taking it back to store, ordered another online. I don't want a returned item - not trusting of what problem(s) the other person had.
by TimUpstate
3 people found this helpful
Great product for under sink - instant hot water - vs waiting for the water from the other side o...
Great product for under sink - instant hot water - vs waiting for the water from the other side of the house. Installed in the supply for the sink faucet and the dishwasher.
by savingwater
1 person found this helpful
Mounted in line with hot water supply. We now have hot water almost as soon as the tap is opened....
Mounted in line with hot water supply. We now have hot water almost as soon as the tap is opened. If you have flexible sink connections from shut off valves, it's a fairly easy install for the experienced DIY. It takes up a lot of room under the sink so measure twice before you buy. Keep in mind the pressure relief valve requires a place to discharge!
by fasteddie
4 people found this helpful
The usual use for this mini-tank water heater is to use at a sink or bathroom located far from th...
The usual use for this mini-tank water heater is to use at a sink or bathroom located far from the house water heater so there will be hot water right at the tap. I have put it to a different use. I've installed a high efficiency heat pump water heater to supply heat to our house in-floor hydronic heating system. The heat pump system is heat pump only, not hybrid with electric resistance heating back-up. Since the heat pump system maximum capacity is very close to the calculated design day heat loss from the house I wanted to add a little bit of electric resistance heating into the tempered water that flows to the floors. The tempering valve is set to about 100 to 105 degrees fahrenheit and the heat pump system is able to produce water that maintains that temp most of the time. I added the mini-tank heat in the line that distributes water to the floors add I'll set the temp at about 80 degrees just to be sure there is a way to add some heat if the heat pump isn't quite producing enough heat. I'm still setting it up and we haven't had very low outside temps yet so I'll have to wait to see how well it performs. I really appreciate that this water heater can be set as low as 65 degrees, so 80 degrees will fall right into it's operational range. The attached photo shows the tank installed during leakage checking and before the pipe insulation and temp setting happened.
by JayJay
1 person found this helpful
Its great easy to instal space saver very eficient
Its great easy to instal space saver very eficient
by Vichdez
It gets the water hot
It gets the water hot
by Shawn
1 person found this helpful
Showing 1-10 of 486 reviews