Water heaters
Rheem Performance RETEX-24 Self-Modulating Electric Tankless Water Heater
Prices are the equipment only — the appliance, before install labour. Every product in this catalogue currently has at least one real, seller-observed equipment price (see the SKU verification and price observation notes on each product). Get contractor quotes for the install itself, especially for anything needing new electrical circuits or condensate drainage.
Rheem's 24kW retail electric tankless delivers 4.68 GPM at a 35°F rise, but it needs three 40-amp double-pole breakers. It carries a 5-year heat-exchanger warranty and just 1 year on parts.
Our take
Rheem sells two different 24kW electric tankless lines that look almost identical in a search result: the retail 'Performance RETEX-24' (this one, sold at Home Depot) and the wholesale 'Professional Classic RTEX-24' -- no E -- which carries different UEF and warranty terms. Make sure whatever price you're comparing is actually for this unit. Against the Stiebel Eltron Tempra 24 Plus a shelf over, the two are close on paper -- same 24kW, same 0.93 UEF, both land around 4.68 GPM at a 35°F rise. The practical divide is electrical capacity and warranty. RETEX-24 needs roughly 100 amps of dedicated capacity, and its 1-year parts cover is thin beside the Tempra's 3 years on parts and 7 years limited. The exact-model owner sample is small, but it reinforces the same buying questions: size for winter inlet temperature, confirm the panel before ordering, and do not treat the headline GPM as a promise under every draw.
Best for
A one- to two-bath home in a warm or moderate climate, with enough panel capacity for three 40-amp double-pole breakers and a buyer who values the compact footprint over a longer parts warranty.
Watch out for
Don't confuse this with the wholesale 'RTEX-24' (no E) -- different product, different numbers. Cold inlet water or a high shower flow can push this 24kW unit past its comfortable range. Three of the 10 exact-model reviews retained for this page describe a failed or dead unit, so the 1-year parts warranty deserves real weight in the choice.
What sellers are actually charging
The lowest in-stock, full-equipment price we've seen is $543, at Home Depot, seen 2026-09-17. Every listing from the last 30 days, newest first, is below — prices change, click through to check before you act on any of them.
| Seller | What you get | Price | Stock | Seen |
|---|---|---|---|---|
| Home Depot
big box retailer |
equipment system | $543 | in stock | 2026-09-17 |
| Home Depot
big box retailer |
equipment system | $549 | in stock | 2026-08-30 |
Equipment price is not installed price. The listings above are what the hardware costs. Installation — labour, electrical, refrigerant lines, permits, removing the old system — is typically a similar amount again, and varies more between contractors than between brands. Where we have an installed figure it is labelled as such and comes from someone who actually installs.
What owners and installers report
Collected from trade forums, owner communities and video reviews. Every report links to the original. We synthesise and quote briefly — we don't republish other people's writing.
Reliability and failures
What breaks, when, and how often — from people several years in.
Thin evidence — too few independent reports to call this a pattern. Shown because it may still be worth asking your contractor about.
In the 10 exact-model reviews retained from Home Depot, 6 mention reliability; 3 describe a problem.
Automated synthesis of 10 exact-model reviews · Home Depot ratings · read it in context
Owner of the sibling RETEX-18 (same self-modulating electric-tankless platform as the cataloged RETEX-24, different kW rating) reports the unit stopped heating entirely after a routine descale/deliming, pushing only cold water through; resolution not confirmed in-thread.
“We just delimed our Rheem RETEX-18 tankless water heater. After hooking it back up, it doesn't heat water at all, just pushes cold water through.” — N08LE homeowner, 2025-03-17
Reported on the Performance RETEX line; size not stated — included here because it's the same family and counts toward the totals above.
Rheem tankless water heater not heating after deliming · Terry Love Plumbing Forum · 2025-03-17 · read it in context
Sources are linked so you can verify any of this yourself. We don't mirror content — Amazon in particular permits no republication of review text, so where we use retailer data we show the aggregate rating and link out. How we collect and weight this →
Before you buy — install and sizing lessons
Reported issues about installation, sizing, or the dealer/installer — not the equipment itself. These don't affect the ratings above; they're what to ask your contractor about before you sign a contract.
Installation and commissioning · installation
The guide flags the electrical load as the main installation constraint: three 40-amp double-pole breakers and roughly 100 amps of dedicated capacity.
Best Rheem Tankless Water Heaters 2026 · Independent trade-company blogs · read it in context
Sizing and capacity in practice · sizing
The guide treats RETEX-24 as a fit for a one- to two-bath home in a warm or moderate climate, and warns that colder inlet water reduces real flow.
Best Rheem Tankless Water Heaters 2026 · Independent trade-company blogs · read it in context
Compare against
Stiebel Eltron Tempra 24 Plus Electric Tankless Water Heater
Stiebel Eltron's Advanced Flow Control electric tankless: 24kW, UEF 0.93, roughly 4.68 GPM at a 35°F-equivalent rise, a 3-year parts warranty (7-year limited).
A. O. Smith Voltex X Split Heat Pump Water Heater, 47 gal
Outdoor CO2 split-system heat pump water heater introduced in August 2026, with a 47-gallon indoor tank and a model-specific UEF of 3.52.
GE Profile GeoSpring Smart Hybrid Heat Pump Water Heater, 50 gal
GE's flagship heat pump water heater, relaunched under the Profile line with FlexCAPACITY mixing and Wi-Fi control. ENERGY STAR-certified at UEF 4.50 -- the highest efficiency figure in this catalogue at any size.
GE Profile GeoSpring Smart Hybrid Heat Pump Water Heater, 80 gal
80-gallon version of the same Profile GeoSpring Smart Hybrid platform as the 50-gallon model -- same UEF 4.50, larger first-hour rating.
Before you buy this
Ask for the first-hour rating, not just tank size, and check it against your household's simultaneous demand — showers and laundry at the same time — rather than headcount alone. If it's a heat pump water heater, confirm the room has enough air volume (or a duct kit) that it won't spend winter on resistance backup, and that there's a real route for condensate, not just a nearby floor drain. Confirm the panel has spare 240V capacity. And if you're removing a gas unit that shared a flue with a furnace, ask what happens to that flue once your water heater's draft is gone — an orphaned flue can backdraft.