The T-K series is Takagi's non-condensing tankless. Lower upfront cost than T-H3/T-D2 condensing but requires Category III stainless venting (not PVC), and lower 0.82 UEF efficiency.
T-K lineup
- T-K4-IN-NG — 190k BTU, 8.0 GPM, indoor NG
- T-K4-OS-NG — outdoor (no venting required)
- T-K4-IN-LP — propane indoor
When T-K is right
- PVC venting is difficult or expensive in your install
- You want existing chimney-route compatibility (stainless Category III may share an existing flue)
- Budget constraint: $300-500 less than T-H3 condensing
- Warm-climate outdoor install (T-K4-OS eliminates venting entirely)
When condensing wins
- Most US installs — condensing pays back in gas savings over 4-6 years
- 15-year warranty (vs 10-year T-K)
- PVC venting is cheaper than stainless Category III
Warranty
10 years heat exchanger / 5 years parts / 1 year labor.
Pricing
- T-K4-IN-NG: $999-1,249
- T-K4-OS-NG outdoor: $1,099-1,349
- T-K4-IN-LP propane: $1,199-1,449
Bottom line
T-K is the budget alternative to T-H3 condensing. For most US installs, condensing wins on lifetime cost. Choose T-K when PVC routing is difficult or when budget is the dominant factor.