Rheem RTG-84XLN Tankless Natural Gas Water Heater

Hot water on demand is probably the second most important thing for a home after an air heater. That is why the type and varieties of water heaters are plenty in market. Rheem RTG-84XLN Tankless Natural Gas Water Heater is one of such type that gives you 8.4 GPM at 35-Degree Rise. It can serve the hot water need of a home with 3-5 bath rooms, where occasionally 2 bath rooms are used simultaneously, if you live in a colder place. If your residing climate is as soothing as North Carolina you can use 3 bathrooms at a time with normal water flow. It consumes 180,000btus, so check your pipe sizes before buying it or you can switch to new pipes. 

Rheem RTG-84XLN Tankless Natural Gas Water Heater


According to best tankless gas water heater reviews it is quite energy efficient 82% that is in figures. Want to know more? Here are the details-

Saves water

If you are that person who want all luxury but also is very concerned about the wastage than you would be glad to know Rheem understand the value of saving and preserving. Rheem RTG-84XLN Tankless Natural Gas Water Heater has this exclusive! Water savings setting that allow saving up to 1,100 gallon of water per year. How does it do so? Well it decreases the flow of water through the pipes waits for the temperature to reach to the heater’s set temperature.

Compatible to Low flow fixture

Did you ever face problem of your water heater to not start at all or taking a lot of time to start because your flow rate is lower than most places and borderline with tank less gas water heater’s activation rate? Well that is not going to happen with this model of Rheem. It has minimum flow rate of o.26 Gallon per Minute and a minimum activation flow rate of 0.40 Gallon per Minute. Even if you are living at a very low water condition you won’t be deprived of hot water supply.

Hot water at first touch

Tankless gas water heater reviews always ask you to buy Re-circulation Pump Kit or other accessories to be able have full performance from a tank less water heater. That is to have hot water from your very first moment of opening faucet. It does not happen with usual tank less water heater as the burner starts to heat only after sensing the flow and it takes time with activation rate and all that and available re-circulation pump kits do not always pair up with the heaters seamlessly. However with Rheem RTG-84XLN Tankless Natural Gas Water Heater you can easily pair it up with their Re-circulation Pump Kit and never worry about the delay of hot water.

No more “cold water sandwich”

Rheem RTG-84XLN Tankless Natural Gas Water Heater has smart programming that helps to minimize the fluctuation in water temperature. So you will enjoy a long bath with same temperature of hot water and flow rate will be adjusted evenly to ensure no fluctuation. It is Time to say good bye to cold water sandwich problem from frequent on off operation.

Works at high altitude capability

If you are afraid to switch to tankless water heater because of your high altitude, then worry no more. This model of tank less gas water heater can smoothly function at as high altitude as 8,400 ft. elevation above sea level.


It ensure safety from overheating by Guardian OFW™ overheat film wrap

  • Product comes with cable for higher demand applications. It connects two tank less units to work as one
  • It is Environmentally friendly with ultra-low NOx compliance
  • Rheem RTG-84XLN 8.4 comes with UMC-117 remote control
  • With 14 x 10 x 26 inches it is 5 times space saver than tank water heater
  • Slim and good looking
  • Digital regulator to control heat

Cons with solution

Hard to maintain

This tankless unit can not last long as they get stored with mineral inside.


That is true for all out door tank less water heaters. What you need regular maintenance for longevity is Rheem RTG20220 Tankless Water Heater Service Valve Kit with Pressure Relief Valve or you can look for same type of valve of other company. These shutoff valves will help you to comply with the code too. They let you isolate the unit from the system quickly in case of a servicing /maintenance/repair issue. It helps to add, service ports for flushing the heater with vinegar or to remove mineral that may store up in the heat exchanger.

It freezes

If you are planning to put it at outdoor (you have to it is an outdoor model) you may have problems to protect it from hard weather conditions. If you are at Canada or North America you may think twice as its pipe can get frozen at times and break eventually.


Yes it can so can any other outdoor heater. If you install them out door they are prone to, freezing, bumping by other object etc. This model is in fact less susceptible to cold weathers as it has Freeze protection to 30°F.

Also you can find a cover in market to protect it from other object. You will find Rheem grey pipe covers for the covering purpose that will protect the heater pipes.

Frequently Ask Questions

  • Q- What warranty it offers?
  • Ans-Warranty for Parts - 5 Years
    Labor charges of repair for 1 Year
    Heat Exchange warranty for 12 Years
  • Q- Why cannot I use it indoor?
  • Ans- Rheem has indoor units too. The reason this unit is to be installed outside is probably the proper ventilation of carbon monoxide.
  • Q- How easy/hard is the installation?
  • Ans- Users say it is moderately easy if you have researched a lot and have seen the videos.


Which tankless water heater to buy is not an easy decision? It needs you to consider many things other than your number of bathroom and water flow. You may need to analyze your ground water temperature, conditions and altitude too. However Rheem RTG-84XLN Tankless Natural Gas Water Heater is susceptible to hard weather and hard water conditions with a capacity to meet a reasonable magnitude of demand. So it is not a risk to choose this 4.4 star ranked product for a long time ceaseless hot water supply.

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