Rheem RTEX 13 Review


Rheem is a renowned manufacturer of tankless water heaters (electric and gas). Rheem RTEX 13 has received appreciation and acceptance from consumers all over the world due to its space-saving design and efficiency. This energy star certified ingenious unit will not just supply warm water instantly on demand but the unit’s energy saving feature will let you reclaim both the unit & installation costs within 17 months. Its main features are:
  • On-unit heat regulation
  • LEDs direct active element
  • Contains Standby mode
  • Standard 1/2" water link
  • Durable brass/copper heat exchanger
  • Modulating power
The Rheem RTE 13 is a powerhouse when it comes to performance as it can heat upto 4gallon water per minute. It has been designed for indoor usage primarily homes, condos, offices, labs and/or hospitals.

The Pros & Cons of the Rheem RTEX 13


  • This tankless unit is very compact and space-saving.  Fits almost anywhere
  • The unit doesn’t store water inside and supplies hot water within seconds once the switch is turned on.
  • Heats up to 4gallons water per minute, which proves its efficiency
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    Energy-saving mechanism minimizes electricity bills
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    Doesn't require venting
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    Modulating heat exchanger prevents standby heat loss


  • The unit is not feasible for being used by large families because it cannot fulfil high demand for hot water
  • Additional components are required to be bought to enhance the unit’s functioning
  • It requires extra wiring and a 60amp circuit breaker

Installation and Specifications

The heater’s compact size makes it easy to be installed just about anywhere. The installation process is simple and easy. You don’t need to assemble different parts before mounting the heater because it is a single unit. All that needs to be done is to mount the device on to the wall and connect the pipes for water supply.


Assembled Depth3"
Assembled Height10"
Assembled Width7.25"
Product Depth3"
Product Height10"
Product Width7.25"
Water Connection Size1/2
Amperage (amps)54
Electric Product TypePoint of Use
Finish FamilyGray
Flow Rate @ 35 F Rise (gallons/min)2.54 gal (US)/min
Flow Rate @ 45 F Rise (gallons/min)1.97 gal
Fuel TypeElectric
Maximum Temperature (F)125
Minimum Activation Rate (gpm)0.4
Minimum Temperature (F)0
Product Weight (lb.)8 lb
Residential/Commercial/industrial UseResidential or comercial
ModelRTE 13
Voltage (volts)240
Water Connection LocationSide
Water Heater FeaturesNo Additional Features
Wattage (watts)13000

Common Problems

Rheem RTE 13 is an efficient model and ideal for domestic usage but a few concerns are still there. Some of the units have inherent technical faults that potentially affect its performance. Another issue is that you require at least 3inch extra copper tubing that has to be passed on both the sides of the unit. If you have plastic piping then you will have to change it as well. Moreover, you need to have electricity service that can handle a 240v/60amp circuit breaker. The user manual states that unit requires 6ga wire but in reality it utilizes 8ga.


This water heater is perfect for small families. For larger homes it is also feasible but you will have to install two units to satisfy high demand. The energy-saving and eco-friendly feature of the unit makes it highly suitable for every household. Moreover, it is not very expensive in comparison to gas tankless units or tank heaters and you can easily reclaim the expenses afterwards by reducing monthly electricity bills.

You can buy the Rheem RTEX 13 on Amazon.

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