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Written from the listing's specs, not from our own use · How we rate
The Rheem RETEX-36 Performance (36 kW) packs up to 6 GPM, 36 kW of heating power and self-modulating power into one electric tankless heater. Think of it for two showers at once where gas is not an option: 5.9/10 on what its listing documents.
| Brand | Rheem |
|---|---|
| Category | Electric tankless water heaters |
| Fuel | Electric |
| Stated maximum flow | 6 GPM |
| Stated heating power | 36 kW |
| ASIN | B0785TV3HV |
Full listing title: Rheem RETEX-36 Performance 36 kw Self-Modulating 6 GPM Electric Tankless Water Heater
| Fuel | 36 kwFull listing title |
|---|---|
| Stated maximum flow | 6 GPMFull listing title |
| Stated heating power | 36 kwFull listing title |
Rated from the listing's specs, no buyer reviews yet
What it's made for: two showers at once where gas is not an option.
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 150 A. Before you think about showers, your electrician has to say yes to that number at the panel in the garage.
What it has going for it
6 GPM max. That is the headline figure, usually at a modest temperature rise. Our calculator counts a shower at 2 GPM, so think one shower and a sink at a time, maybe two showers where the water comes in warm.
Self-modulating. It draws only the power the flow and the setpoint need, instead of slamming every element on. Steadier temperature, and no wasted amps on a summer afternoon.
Warm tap water: where it comes in around 62 °F (much of the South), 36 kW gives about 5.7 GPM of 105 °F water on our calculator's maths. That's two 2 GPM showers at once.
A cold January: where it comes in at 42 °F, it's about 3.9 GPM, one 2 GPM shower at a time. Up north, that's the figure to size against, and it's why the honest answer is sometimes a second unit or gas.
What the Rheem RETEX-36 Performance (36 kW) listing names:
The installation manual has the last word on breakers and wire size; show it to your electrician before you order.
At the price on Sep 30, 2026, each kW of stated heating power works out at about $20.92 (price ÷ stated kW, our arithmetic). That puts it around the middle of the 27 whole-house electric tankless heaters we have a price and a stated power for.
The online price is the heater alone. New double-pole breakers, heavy-gauge wire and the electrician's visit are extra, and an older panel may need an upgrade first.
The button opens the exact listing (ASIN B0785TV3HV), where today's price, stock and seller apply.
Panel short on spare amps? The Rheem 18 kW Electric, 240V (9.3/10) is rated 18 kW, about 75 A at 240 V.
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 to spend less? The WINTEMP WN-36kW Electric, 240V (8.1/10) was listed at $499.98 on Sep 30, 2026.
Our take
The Rheem RETEX-36 Performance (36 kW) earns its place with up to 6 GPM and 36 kW of heating power. No buyer reviews yet, so this Rheem electric tankless heater has to win you over on paper. The catch with the Rheem RETEX-36 Performance (36 kW): no word on the breakers it needs. We'd pick it if you run one shower and the kitchen tap at once, rarely more; otherwise, put it next to the MRNIU 36 kW Electric (240V) 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, and the power steps up and down with the flow (self-modulating, per the listing). Set it, then leave it.
With 42 °F water coming in, 36 kW gives about 3.9 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 Rheem RETEX-36 Performance (36 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, 36 kW gives about 3.9 GPM with 42 °F winter water and 5.7 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 Rheem RETEX-36 Performance (36 kW) stacks up against the closest alternative, the MRNIU 36 kW Electric (240V).
| Criterion | Rheem RETEX-36 Performance, 36 kW | MRNIU 36 kW Electric, 240V |
|---|---|---|
| Our rating | 5.9/10 | 5.9/10 |
| Max flow | 6 GPM | Not stated |
| Voltage | Not stated | 240 V |
| Self-modulating | Stated | Not stated |
| Buyer reviews | None captured | 5 · 4.4/5 |
Both score 5.9/10. The Rheem RETEX-36 Performance (36 kW) brings more stated flow (6 GPM) and self-modulating power, so it has the edge on paper.
We rate it 5.9/10 (fair). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a maximum flow of 6 GPM and a heating power of 36 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 up to 6 GPM, 36 kW of heating power and self-modulating 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, 36 kW gives about 3.9 GPM with 42 °F winter water and 5.7 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.