Ranein RH8K-NG 80,000 BTU Natural Gas Tankless Water Heater

What it delivers

The Ranein RH8K-NG 80,000 BTU Natural Gas Tankless Water Heater is a non-condensing gas tankless with a 80,000 BTU/h burner and a stated maximum flow of 3.6 GPM.

At a 45°F rise (mild inlet water to a 120°F set point) it holds about 2.7 GPM, 1 shower at 2 GPM; in winter, at a 70°F rise, about 1.8 GPM, less than one 2 GPM shower. Size it to your fixtures and climate.

The line must deliver about 77 cubic feet of natural gas an hour when it fires flat out. The requirement calculator adds it up; a licensed fitter confirms the pipe.

Its exhaust runs hot, so the vent must be the material its manual lists, usually stainless; budget for the vent kit.

From the listing: features: LED Display; connections: 1/2" npt; material: 3.6GPM 80,000 BTU (Indoor); model: RH8K-NG; warranty: 2 Year Manufacturer.

The listing gives dimensions of 13.8 in (W) x 21.7 in (H).

Warranty, per the listing: 2 Year Manufacturer.

Right unit for this house?

Install it when

One shower at a time in cold climates
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

80,000 BTU/h input
Up to 3.6 GPM

Trade-offs

Gas pipe sizing to confirm
Stainless venting costs more
Scale builds up without flushing

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	RH8K-NG	Retailer
Dimensions (seller)	13.8"W x 21.7"H	Retailer
Features (seller)	LED Display	Retailer
Voltage	120 V AC	Retailer
Max flow (maker)	3.6 GPM	Retailer
Input (maker)	80,000 BTU/h	Retailer
Material	3.6GPM 80,000 BTU (Indoor)	Retailer
Warranty	2 Year Manufacturer	Retailer
Fuel	Natural Gas	Retailer
Connections	1/2" npt	Retailer

Rival units at this flow

APUS AP-AWH-Q10NG 80,000 BTU Natural Gas Tankless Water Heater80,000 BTU/h, up to 3.6 GPM.

forimo CT1314-HWRSQ Tankless Water Heater81,888 BTU/h.

RIWORY RWRHT008 85,000 BTU Natural Gas Tankless Water Heater85,000 BTU/h, up to 3.6 GPM.

More gas tankless water heaters rated for similar demand

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

Final verdict

A solid non-condensing gas tankless for one shower at a time in cold climates.

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Questions buyers ask

What flow does the Ranein RH8K-NG 80,000 BTU Natural Gas Tankless Water Heater give in winter?

From its 80,000 BTU/h input we estimate about 2.7 GPM at a 45°F rise and 1.8 GPM at a 70°F rise, so 1 two-GPM shower with mild inlet water and 0 in a cold winter. The maker's flow chart for this model is the final word.

What size gas line does the Ranein RH8K-NG 80,000 BTU Natural Gas Tankless Water Heater need?

At full fire it uses about 77 cubic feet of natural gas an hour. 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.