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Written from the listing's specs, not from our own use · How we rate
The Bosch Tronic 6100 (18 kW) is an electric tankless heater built around 18 kW at 240 V. It makes most sense for a southern house with warm tap water and no gas line; we rate it 6.5/10 from its listing.
| Brand | Bosch |
|---|---|
| Category | Electric tankless water heaters |
| Fuel | Electric |
| Stated heating power | 18 kW |
| ASIN | B0BWKCCQ1V |
Full listing title: Bosch Thermotechnology Tronic 6100 Electric Tankless Water Heater, 18 kW, White
| Fuel | ElectricFull listing title |
|---|---|
| Stated heating power | 18 kWFull listing title |
Rated from the listing's specs, no buyer reviews yet
What it's made for: a southern house with warm tap water and no gas line.
Two electric tankless heaters of about the same power, closest to it on our rating, each with a dated price.
The heating power the listing states. At 240 V it draws about 75 A. That's the line to show your electrician before anything else: the panel decides whether this fits, not the shower.
Warm tap water: where it comes in around 62 °F (much of the South), 18 kW gives about 2.9 GPM of 105 °F water on our calculator's maths. That's one 2 GPM shower at a time.
A cold January: where it comes in at 42 °F, it's about 1.9 GPM, less than one 2 GPM shower. Up north, that's the figure to size against, and it's why the honest answer is sometimes a second unit or gas.
At the price on Sep 30, 2026, each kW of stated heating power works out at about $34.94 (price ÷ stated kW, our arithmetic). That puts it in the pricier third of the 27 whole-house electric tankless heaters we have a price and a stated power for.
Budget for the electrician as well: new double-pole breakers, thick wire from the panel and, if the panel is full, an upgrade.
The button opens the exact listing (ASIN B0BWKCCQ1V), where today's price, stock and seller apply.
Colder tap water where you live? The WINTEMP WN-36kW Electric, 240V (8.1/10) is rated 36 kW.
Only one sink far from the heater? The ThermoMate 14 kW Electric, 240V (7.9/10) is a 14 kW point-of-use unit.
Want it to draw only what it needs? The Rheem 18 kW Electric, 240V (9.3/10) is self-modulating, per its listing.
Our take
The Bosch Tronic 6100 (18 kW) is about 18 kW at 240 V, and it doesn't pretend to be more. No buyer reviews yet, so this Bosch electric tankless heater has to win you over on paper. The catch with the Bosch: no stated self-modulation, while most picks here have it. We'd pick it if you live somewhere the tap water never gets icy; otherwise, put it next to the Bosch Tronic 6100 (27 kW) first.
New breakers, the unit on the wall next to the old tank's spot, water in and out. An electrician does the panel side.
Hot in a few seconds once the water in the pipes has passed. Set it, then leave it.
With 42 °F water coming in, 18 kW gives about 1.9 GPM at 105 °F on our calculator's maths. Low-flow shower heads stretch that further.
Clean the inlet screen and flush out scale on hard water. Our flushing and descaling guide has the routine.
Before you order the Bosch Tronic 6100 (18 kW), check your panel: the listing doesn't spell out the breakers, so ask before an electrician quotes the job.
Take a photo of the panel label (main breaker size and free slots) and send it to the electrician with the listing. Our electrical requirements guide explains what they will look for.
On our calculator's maths, 18 kW gives about 1.9 GPM with 42 °F winter water and 2.9 GPM with 62 °F water. Our flow-rate calculator does it for your region.
Hardwired 240 V work needs a licensed electrician and often a permit. Our install cost guide shows what usually ends up on the quote.
Hard water still builds up on the elements and the inlet screen. Our flushing and descaling guide covers the routine.
How the Bosch Tronic 6100 (18 kW) stacks up against the closest alternative, the Bosch Tronic 6100 (27 kW).
| Criterion | Bosch Tronic 6100, 18 kW | Bosch Tronic 6100, 27 kW |
|---|---|---|
| Our rating | 6.5/10 | 6.6/10 |
| Heating power | 18 kW | 27 kW |
| Warranty | Not stated | 5 years |
Pick the Bosch Tronic 6100 (27 kW) if you want our higher-rated option (6.6/10), with more power (27 kW) and a longer stated warranty (5 years).
We rate it 6.5/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a heating power of 18 kW. The headline flow is a mild-weather number: with cold winter water coming in, the same unit gives you less. Read the maker's flow chart at your winter rise, or let our flow-rate calculator do the sums.
The listing doesn't state the voltage, so check the maker's documents. A licensed electrician checks the panel, the breakers and the wiring before it goes on the wall.
Its listing states 18 kW of heating power. These are the seller's figures, not our measurements: how steady the temperature is in your shower and how it copes with your winter water can't be read from a listing.
Your panel: take a photo of the panel label (main breaker size and free slots) and send it to the electrician with the listing. Our electrical requirements guide explains what they will look for. Your winter flow: on our calculator's maths, 18 kW gives about 1.9 GPM with 42 °F winter water and 2.9 GPM with 62 °F water. Our flow-rate calculator does it for your region. The install: hardwired 240 V work needs a licensed electrician and often a permit. Our install cost guide shows what usually ends up on the quote. Scale: hard water still builds up on the elements and the inlet screen. Our flushing and descaling guide covers the routine.
We link to the exact listing on Amazon, where today's price, stock and seller apply. It is an affiliate link, and it has no effect on the rating.
No, we haven't used it ourselves. Everything on this page comes from its listing, read line by line and weighed with our published formula.