RTEX-24: capacity and installation fit
The RTEX-24 sits between the two-circuit RTEX-18 and the higher-output RTEX-27. This 24 kW electric tankless heater uses three dedicated circuits and can be considered for overlapping fixture use when the home’s electrical supply and incoming water temperature support it. WHE evaluates the full conversion rather than matching the model to bathroom count alone.
Water Heating Experts helps homeowners in Palm Beach Gardens, Jupiter and nearby Palm Beach County compare the Rheem RTEX-24 with their current equipment. Start with the Rheem installation overview for the wider range, or use the specifications below to discuss this exact model. It heats water as it flows and has no stored-gallon capacity.
Electrical requirements for the RTEX-24
| Specification | Published 240 V requirement |
|---|---|
| Heating input | 24 kW |
| Supply | 240 V, single phase |
| Total unit current | 100 A |
| Dedicated circuit protection | 3 × 40 A double-pole breakers |
| Manufacturer wire listing | 3 × 8 AWG; 75°C insulation |
| Recommended household service | 200 A; electrical load assessment required |
These are the model-row values in Rheem’s July 2026 specification sheet, RH-TE-WH-SS Rev. 1. The household service recommendation is different from the heater’s branch-circuit protection. A qualified electrician must confirm available capacity, conductor sizing, circuit routing and applicable installation requirements. An existing tank-water-heater circuit should never be assumed to support this conversion.
The ratings here are specifically for 240 V. A property supplied at 208 V needs a separate performance and electrical review: lower voltage reduces heating output, so the 240 V flow figures do not carry over unchanged. Tell WHE about other large electrical loads or planned additions when discussing the project.
Flow depends on incoming water temperature
| Incoming water → outlet set point | Rheem flow example |
|---|---|
| 67°F → 105°F (38°F rise) | 4.3 GPM |
| 72°F → 105°F (33°F rise) | 5.0 GPM |
| 77°F → 105°F (28°F rise) | 5.9 GPM |
Rheem’s 67°F inlet example gives the RTEX-24 4.3 GPM to a 105°F outlet. A pair of 2 GPM showers would consume most of that illustrated capacity; adding a kitchen faucet could exceed it. At 77°F inlet, the chart increases to 5.9 GPM. These examples show why a warm-climate location helps but does not establish a fixed number of fixtures the unit can always serve.
These are manufacturer sizing examples at a 105°F set point, not a recommendation for every household’s temperature setting. Your actual inlet temperature varies with the property and season. List the fixtures used together and their flow rates; bathroom count by itself does not describe the load. Higher outlet temperatures require more heating for each gallon and reduce available flow.
Controls, efficiency and everyday use
The RTEX-24 has digital temperature adjustment and modulates heating power as demand changes. Rheem lists 0.93 UEF for this model in the current specification table. UEF is a standardized efficiency rating, not a guaranteed percentage reduction in your electricity bill. Avoid comparing it directly with marketing statements about heating-element efficiency.
There is no storage tank to deplete, but the heater still has a limit on how much water it can heat at once. It also does not eliminate the water already sitting in long hot-water pipes. If your main concern is waiting for hot water at a distant bathroom, explain that separately from a problem with the heater keeping up once water arrives.
Dimensions, location and service access
Rheem’s July 2026 table lists 17 inches high × 17 inches wide × 3.625 inches deep, with bottom ¾-inch NPT water connections. These are cabinet dimensions, not the complete installation envelope. Allow space for plumbing, wiring, mounting and service access; confirm dimensions against the supplied unit before preparing the location.
The linked installation and owner’s manual specifies indoor installation and recommends 12 inches above and below the heater and 6 inches in front and at the sides. The location also needs protection from freezing, splashing and moisture. WHE reviews access and leak protection when assessing a replacement location.
Compare the RTEX-24 with nearby sizes
The RTEX-27 uses the same number and published rating of branch circuits and the same cabinet dimensions in the July 2026 specification table. It raises output from 24 to 27 kW and published total current from 100 to 113 A. The RTEX-18 has fewer circuits but less capacity; comparing these three models helps identify which tradeoff fits the project.
Compare Rheem RTEX-18, Rheem RTEX-27, Rheem RTEX-36, or browse the water heater model catalog. A suitable electric storage heater can also be part of the comparison when installation space, electrical work and the household’s usage are considered together.
Maintenance and limited warranty
Tankless equipment still needs maintenance. Water quality and scale affect the service plan, and the manufacturer calls for regular attention to plumbing connections. Ask about accessible service valves and maintenance needs when planning the installation. Keep the model and serial number, receipt and installation record available for future service.
Rheem’s limited warranty describes qualifying leak coverage for five years and component coverage for one year, subject to its terms and exclusions. Labor is not included in that manufacturer coverage. Coverage is determined by the applicable warranty and the cause of failure; it is not a promise of free installation or all repairs.
RTEX-24 questions
How is the RTEX-24 different from the RTEX-27?
The RTEX-24 provides 24 kW and draws a published 100 A at 240 V. The RTEX-27 provides 27 kW and draws 113 A. Both have three 40 A double-pole circuits and the same listed cabinet dimensions. The 27 offers more heating capacity, subject to electrical suitability.
Does an existing 200-amp panel mean the RTEX-24 will fit?
Not by itself. The 200 A figure is Rheem’s household service recommendation. A qualified electrician must assess other loads, available capacity and the three dedicated circuits. Empty breaker spaces do not establish that the service can support the additional load.
Can the RTEX-24 be installed outdoors?
The linked Rheem manual specifies indoor installation. WHE reviews a protected, accessible location and the space needed for service and connections before recommending the equipment.
Does the RTEX-24 need a gas line or vent?
It uses electric resistance heating, so it does not need a gas supply or combustion vent. The project still requires correctly designed electrical circuits, plumbing connections and an appropriate indoor location.
What does an installed RTEX-24 cost?
WHE quotes each installation individually after reviewing the heater, electrical requirements, plumbing and access. Send photos of the current installation and model label, and describe the fixtures that need hot water together. Equipment availability is confirmed during the estimate.
Ask WHE about the Rheem RTEX-24
For help comparing this model, text photos to 561-602-9062, call WHE or request a free installation estimate. Include your location and the problem you want the new heater to solve. Our installation service page explains the next steps.