Rheem RTG-84XLP-3 180,000 BTU Propane Tankless Water Heater

What it delivers

The Rheem RTG-84XLP-3 180,000 BTU Propane Tankless Water Heater is a propane tankless with a 180,000 BTU/h burner and a stated maximum flow of 8.4 GPM.

Expect about 4.0 GPM with cold winter water (a 70°F rise) and 6.2 GPM when the inlet is milder (45°F rise); that is 1 shower at 2 GPM in January. Run your house through the planner.

At full fire it burns about 2.0 gallons of propane an hour. The gas line has to carry that on top of the furnace, range and dryer; a gas fitter sizes the pipe from its length and the total load.

Non-condensing indoor units run hot exhaust and vent in the maker's listed vent system (often stainless Category III), which costs more than plastic.

The listing describes its venting as: Outdoor installation.

Listed details: features: Hot-start Programming, 1/2 gas line compatibility, compact design; material: Stainless Steel; model: RTG-84XLP-3; warranty: 1 Year Labor, 15 Year Heat Exchanger, 5 Year Parts.

The listing gives dimensions of 13.5 in (W) x 20.75 in (H), a weight of 39.3 lb and display in the box.

Warranty, per the listing: 1 Year Labor, 15 Year Heat Exchanger, 5 Year Parts.

Right unit for this house?

Install it when

One shower at a time in cold climates
Propane homes
Replacing a gas tank heater

Look at another unit when

More than 1 winter shower at once
Homes without a gas line

Strengths and trade-offs

Strengths

180,000 BTU/h input
Up to 8.4 GPM

Trade-offs

Gas pipe sizing to confirm
Stainless venting costs more
Needs periodic descaling

Install limits

Figures are the maker's or seller's own. Flow at a rise is our estimate from the input; gas, venting and electrical work needs a licensed professional.

Rated performance

Every figure below comes from the source shown in brackets. Where the maker doesn't state something, we say so instead of estimating.

Model number	RTG-84XLP-3	Retailer
Dimensions (seller)	13.5"W x 20.75"H	Retailer
Features (seller)	Hot-start Programming, 1/2 gas line compatibility, compact design	Retailer
Voltage	120 V	Retailer
Max flow (maker)	8.4 GPM	Retailer
Input (maker)	180,000 BTU/h	Retailer
Product weight	39.3 lb	Retailer
Material	Stainless Steel	Retailer
Warranty	1 Year Labor, 15 Year Heat Exchanger, 5 Year Parts	Retailer
Fuel	Liquid Propane	Retailer
Venting	Outdoor installation	Retailer
Condensing	Non-Condensing	Retailer

Rival units at this flow

Westinghouse HW180A0G-LP 180,000 BTU Propane Tankless Water Heater180,000 BTU/h, up to 7.9 GPM.

Marey GA24CSALP 170,000 BTU Propane Tankless Water Heater170,000 BTU/h.

Ranein RH19K-LPG 190,000 BTU Propane Tankless Water Heater190,000 BTU/h, up to 8.5 GPM.

More gas tankless water heaters rated for similar demand

Full gas tankless water heaters spec grid · Every Rheem unit in the catalog

Final verdict

A well-specified propane tankless for one shower at a time in cold climates.

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Questions buyers ask

What flow does the Rheem RTG-84XLP-3 180,000 BTU Propane Tankless Water Heater give in winter?

From its 180,000 BTU/h input we estimate about 6.2 GPM at a 45°F rise and 4.0 GPM at a 70°F rise, so 3 two-GPM showers with mild inlet water and 1 in a cold winter. The maker's flow chart for this model is the final word.

What size gas line does the Rheem RTG-84XLP-3 180,000 BTU Propane Tankless Water Heater need?

At full fire it uses about 174 cubic feet of natural gas an hour or 2.0 gallons of propane. The pipe size depends on the length of the run and every other gas appliance on it; the maker's manual and a licensed gas fitter decide it.