Ranein RH12KG-C-NG 120,000 BTU Natural Gas Condensing Tankless Water H

What it delivers

The Ranein RH12KG-C-NG 120,000 BTU Natural Gas Condensing Tankless Water Heater is a condensing gas tankless with a 120,000 BTU/h burner and a stated maximum flow of 5.1 GPM.

Worked out from its input, it delivers roughly 5.1 GPM when the water only has to rise 45°F, and 3.3 GPM at a 70°F winter rise: 2 showers at 2 GPM in summer, 1 shower at 2 GPM in winter. Size it to your fixtures and climate.

The line must deliver about 116 cubic feet of natural gas an hour when it fires flat out. The requirement calculator adds it up; a licensed fitter confirms the pipe.

As a condensing unit it vents in the plastic pipe (PVC, CPVC or polypropylene) its manual lists and drains an acidic condensate, usually through a neutralizer.

The listing describes its venting as: Category III.

Other listed details: features: LED Display; connections: 1/2" npt; material: Stainless Steel; model: RH12KG-C-NG; warranty: 2 Year Manufacturer.

The listing gives dimensions of 14.2 in (W) x 22 in (H) and a weight of 26 lb.

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

120,000 BTU/h input
Up to 5.1 GPM
Condensing efficiency

Trade-offs

Needs a gas line sized for the load
Needs a condensate drain
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	RH12KG-C-NG	Retailer
Dimensions (seller)	14.2"W x 22"H	Retailer
Features (seller)	LED Display	Retailer
Voltage	120 V	Retailer
Max flow (maker)	5.1 GPM	Retailer
Input (maker)	120,000 BTU/h	Retailer
Product weight	26 lb	Retailer
Warranty	2 Year Manufacturer	Retailer
Material	Stainless Steel	Retailer
Fuel	natural gas	Retailer
Venting	Category III	Retailer
Condensing	Condensing	Retailer
Connections	1/2" npt	Retailer

Rival units at this flow

ThermoMate CZ480NG Natural Gas Condensing Tankless Water Heater114,000 BTU/h, up to 5.3 GPM.

Rinnai RX130iN Condensing Tankless Water Heater130,000 BTU/h, up to 7.1 GPM.

Rheem RTGH-84DVLN-3 157,000 BTU Natural Gas Condensing Tankless Water Heater157,000 BTU/h, up to 8.4 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 sensible condensing gas tankless for one shower at a time in cold climates.

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Questions buyers ask

What flow does the Ranein RH12KG-C-NG 120,000 BTU Natural Gas Condensing Tankless Water Heater give in winter?

From its 120,000 BTU/h input we estimate about 5.1 GPM at a 45°F rise and 3.3 GPM at a 70°F rise, so 2 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 Ranein RH12KG-C-NG 120,000 BTU Natural Gas Condensing Tankless Water Heater need?

At full fire it uses about 116 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.