Takagi T-K4-OS-NG Outdoor Non-Condensing Tankless Water Heater
Takagi T-K4-OS-NG Outdoor Non-Condensing Tankless Water Heater Review
The Takagi T-K4-OS-NG is an outdoor non-condensing tankless water heater. "T-K4" identifies the 190K BTU non-condensing platform; "OS-NG" means outdoor sealed natural gas.
Specs: 190,000 BTU natural gas input, UEF 0.81 (non-condensing), 8.0 GPM at a 35°F rise, copper heat exchanger with stainless secondary, sealed direct-vent exterior mounting. 10-year warranty on heat exchanger.
The outdoor non-condensing configuration is the cost-effective alternative to condensing outdoor variants in warm climates. Lower UEF (0.81 vs 0.95 condensing) means slightly higher operating cost — about $50/year more — offset by lower unit cost.
About $1,500 unit, $2,800 installed. Right buyer: warm-climate primary residence with exterior wall mount location, value-conscious tankless conversion.