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Written from the listing's specs, not from our own use · How we rate
On paper, the Rheem RTEX-13 (240V) gets the important things right: a 3.17 GPM maximum flow and an element that only draws what it needs. It makes most sense for hot water on demand without a gas line; we rate it 6.7/10 from its listing.
| Brand | Rheem |
|---|---|
| Category | Electric tankless water heaters |
| Stated maximum flow | 3.17 GPM |
| Stated voltage | 240 V |
| Total current | 54 A |
| ASIN | B01NAUZJPE |
Full listing title: Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
| Stated maximum flow | up to 3.17 GPMListing text |
|---|---|
| Stated voltage | 240VFull listing title |
Rated from the listing's specs, no buyer reviews yet
What it's made for: hot water on demand without a gas line.
Two electric tankless heaters close to it on our rating, each with a dated price.
What it has going for it
3.17 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 at a time.
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.
What the Rheem RTEX-13 (240V) listing names:
Breakers and wire gauge are in the installation manual, and it overrides anything above; your electrician reads it first.
We have no recent price on file for this listing, so we don't print an old one.
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 B01NAUZJPE), where today's price, stock and seller apply.
Our take
What we'd buy the Rheem RTEX-13 (240V) for is a 3.17 GPM maximum flow, with an element that only draws what it needs as a bonus. No buyer reviews yet, so this Rheem electric tankless heater has to win you over on paper. Where it falls short: no word on the heating power. We'd pick it if you need one shower or one sink at a time, not the whole house; otherwise, put it next to the Rheem RTEX-27 (240V) first.
the unit on the wall next to the old tank's spot, water in and out. Under a sink or on the wall beside it, close to the tap it feeds.
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.
Colder inlet water means less hot flow from the same power. Low-flow shower heads stretch it further.
Clean the inlet screen and flush out scale on hard water. Our flushing and descaling guide has the routine.
Before the Rheem RTEX-13 (240V) ships, check your panel: it draws 54 A, so an electrician should look at the panel first.
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.
The flow an electric unit can deliver falls as the inlet water gets colder. Our flow-rate calculator does the sums 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 RTEX-13 (240V) stacks up against the closest alternative, the Rheem RTEX-27 (240V).
| Criterion | Rheem RTEX-13, 240V | Rheem RTEX-27, 240V |
|---|---|---|
| Our rating | 6.7/10 | 5.8/10 |
| Max flow | 3.17 GPM | Not stated |
| Breakers | 54 A total | Not stated |
On our rating, the Rheem RTEX-13 (240V) comes out ahead (6.7 vs 5.8), and it brings more stated flow (3.17 GPM) on top. Start with this one.
We rate it 6.7/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a maximum flow of 3.17 GPM on 240 V. 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.
Its listing states up to 3.17 GPM 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: the flow an electric unit can deliver falls as the inlet water gets colder. Our flow-rate calculator does the sums 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.