Rheem RTEX 08 Review


Rheem RTEX 08 is an excellent unit for being sued as a point-of-use application and for obtaining hot water whenever required. It is a very compact, light-weight and efficient water heater that can potentially lower your regular energy bills to great extent. It is one of the leading electric water heating units and no other model offers such a wide array of useful features like it does. Here are some of its prominent features:
  • On-Unit control of temperature
  • LED equipped with standby mode and active element
  • 1/2inch water connection
  • Reliable heat exchanger created from brass/copper
  • Power modulating
Just like the case with all Rheem tankless heaters, RTE 9 also doesn’t require T&P valve. Its compact size makes it suitable for all sorts of locations such as condos, hospitals, homes, apartments and offices. It offers a 30degree F temperature rise and you can expect around 5GPM hot water.

The Pros & Cons of the Rheem RTEX 08


  • Compact size and light weight saves storage space
  • Excellent as point-of-use application
  • Easy to mount and simplistic water connections through 1/2inch compression fittings
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    Modulating heat exchanger makes the unit energy efficient
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    Saves energy through the standby mode


  • Not suitable for large families
  • Unit loses efficiency if used by many people
  • Installation although is simple but requires additional wiring and pole breakers, which increases installation cost

Installation and Specifications

The unit’s Use & Care Manual comprehensively informs about the installation procedure. It gets installed fairly easily and quickly. Just mount the heater and an electrical junction box to the area you need to fit it. Plumb the unit into water pipe using the PTC (push to connect) pipe fittings. Flip-off the main breaker and run the 8-gauge wire between the RTE9 and circuit breaker panel and tie it into the junction box using wire-nuts. Lastly, connect the wire to 240V/40amp breaker.


Assembled Depth3"
Assembled Height10"
Assembled Width7.25"
Product Depth3"
Product Height10"
Product Width7.25"
Water Connection Size1/2
Amperage (amps)38
Electric Product TypePoint of Use
Finish FamilyGray
Flow Rate @ 35 F Rise (gallons/min)1.76 gal (US)/min
Flow Rate @ 45 F Rise (gallons/min)1.37 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 9
Voltage (volts)240
Water Connection LocationSide
Water Heater FeaturesNo Additional Features
Wattage (watts)9000

Common Problems

The unit is although being promoted as suitable for large families but in reality it can support no more than two persons at a time. You cannot perform multiple tasks simultaneously such as washing dishes and taking bath, which makes it not suitable for families that demand hot water very frequently. Conversely, response time is very quick and way faster than a gas tankless water heater since a gas unit takes at least 30sec to start warming water whereas RTE9 takes just 15sec. It is an ideal point-of-use application for small family and must be bought if you want to replace gas water heater with an energy efficient electric one.


Definitely go out and get a Rheem RTE 9 electric tankless heater if you live alone and have limited storage space at home. The heater will suffice for your use only and may also support one more person’s needs, but not at the same time. Installation is fairly simple but will cost a little for wiring and pole breakers. If you want to replace your old heater with a new one without too much demand on hot water supply then opt for this one.

You can buy the Rheem RTEX 08 on Amazon.

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