APUS AP-AWH-Q20NG 140,000 BTU Natural Gas Tankless Water Heater

What it delivers

The APUS AP-AWH-Q20NG 140,000 BTU Natural Gas Tankless Water Heater is a non-condensing gas tankless with a 140,000 BTU/h burner and a stated maximum flow of 6.8 GPM. Its listing gives a UEF of 0.81.

Expect about 3.1 GPM with cold winter water (a 70°F rise) and 4.8 GPM when the inlet is milder (45°F rise); that is 1 shower at 2 GPM in January. Check it against your own fixtures.

At full fire it burns about 135 cubic feet of natural gas 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.

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

Listed details: connections: 1/2" npt; material: 6.8GPM 140,000BTU; model: AP-AWH-Q20NG; warranty: 2 Year Manufacturer Warranty.

The listing gives dimensions of 7.09 in (W) x 21.26 in (H) and a weight of 26.9 lb.

Warranty, per the listing: 2 Year Manufacturer Warranty.

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

140,000 BTU/h input
Up to 6.8 GPM
UEF 0.81

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	AP-AWH-Q20NG	Retailer
Dimensions (seller)	7.09"W x 21.26"H	Retailer
Voltage	120 V	Retailer
Max flow (maker)	6.8 GPM	Retailer
Input (maker)	140,000 BTU/h	Retailer
Product weight	26.9 lb	Retailer
Warranty	2 Year Manufacturer Warranty	Retailer
Material	6.8GPM 140,000BTU	Retailer
UEF (maker)	0.81	Retailer
Fuel	Natural Gas	Retailer
Connections	1/2" npt	Retailer

Rival units at this flow

Rinnai RE140eN Natural Gas Tankless Water Heater140,000 BTU/h, up to 5.3 GPM.

Rinnai RE140iN Natural Gas Tankless Water Heater140,000 BTU/h, up to 5.3 GPM.

Camplux CA528 150,000 BTU Natural Gas Tankless Water Heater150,000 BTU/h.

More gas tankless water heaters rated for similar demand

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

Final verdict

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

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Questions buyers ask

Is the APUS AP-AWH-Q20NG 140,000 BTU Natural Gas Tankless Water Heater big enough for two showers?

From its 140,000 BTU/h input we estimate about 4.8 GPM at a 45°F rise and 3.1 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 APUS AP-AWH-Q20NG 140,000 BTU Natural Gas Tankless Water Heater need?

At full fire it uses about 135 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.