Takagi Water Heater Warranty Guide
Manufactured by A.O. Smith Corporation · Warranty info last verified: March 2026
Takagi water heaters are manufactured by A.O. Smith Corporation. This guide covers 3 product lines: the T-KJr2 / T-KJr3 Indoor Tankless, T-K4 / T-H3 Outdoor Tankless, and T-D2 / Commercial Tankless. Across those lines, tank or heat exchanger coverage climbs from 10 years on the T-D2 / Commercial Tankless to 15 years on the T-KJr2 / T-KJr3 Indoor Tankless, parts reach 5 years, and labor runs up to 1 year. The warranty stays with the original owner and does not transfer to later owners, and claims run through 888-882-5244.
Quick Warranty Facts
Tank / H.E. Coverage
10–15 years
Parts Coverage
5 years max
Labor Coverage
1 year
Transferable
No
Extended Warranty
N/A
Registration Required
Recommended
Warranty by Product Line
Coverage periods vary by model series. Check your model against the table below.
| Product Line | Tank / H.E. | Parts | Labor |
|---|---|---|---|
T-KJr2 / T-KJr3 Indoor Tankless 15-year heat exchanger warranty. Residential indoor models. | 15 yr | 5 yr | 1 yr |
T-K4 / T-H3 Outdoor Tankless 15-year heat exchanger warranty. Outdoor installation models. | 15 yr | 5 yr | 1 yr |
T-D2 / Commercial Tankless Commercial-grade tankless units with slightly shorter coverage periods. | 10 yr | 5 yr | 1 yr |
How to Register Your Takagi Water Heater
There is no strict registration deadline listed for Takagi, yet filing it is smart insurance for the 3 lines shown here. Registration puts your purchase date and installer on record so a later claim through 888-882-5244 moves faster.
You will need:
- Serial number (from the rating label)
- Model number
- Installation date
- Installer's name and contact info
- Your name and address
Keep a copy with your Takagi paperwork in case you later call 888-882-5244.
What's Covered
- Defects in materials and workmanship under normal residential use
- T-KJr2 / T-KJr3 Indoor Tankless: 15-year heat exchanger coverage, 5-year parts, and 1-year labor
- T-K4 / T-H3 Outdoor Tankless: 15-year heat exchanger coverage, 5-year parts, and 1-year labor
- T-D2 / Commercial Tankless: 10-year heat exchanger coverage, 5-year parts, and 1-year labor
- Heat exchanger failure on the T-KJr2 / T-KJr3 Indoor Tankless, T-K4 / T-H3 Outdoor Tankless, and T-D2 / Commercial Tankless
What's NOT Covered
Takagi lists 4 situations that fall outside coverage on its 3 lines:
- Improper installation
- Scale and lime buildup from hard water without treatment
- Lack of annual maintenance
- Commercial use of residential models
How to File a Takagi Warranty Claim
- 1
Register your product at takagi.us.com
- 2
Contact Takagi customer service at 888-882-5244
- 3
Technical support assists with troubleshooting
- 4
Warranty parts are provided through authorized service providers
Takagi warranty line: 888-882-5244
Warranty Transferability: No
Warranty is for the original purchaser and installation address only.
Bought a home that came with a Takagi unit? Because Takagi coverage stays with the first owner, the remaining warranty probably did not follow the sale to you, even if the calendar time has not expired. To confirm, decode the serial with our free tool for the manufacture date, then call the Takagi line at 888-882-5244 (labor help is limited to 1 year from install).
Additional Notes
Takagi is a Japanese tankless specialist and is a subsidiary of A.O. Smith Corporation. Known for producing high-quality residential and commercial tankless systems. Their 15-year heat exchanger warranty is among the industry's best.
Related brands with similar warranty terms:
Takagi Warranty FAQ
How many years does the Takagi heat exchanger warranty last?
Takagi tank or heat exchanger coverage ranges from 10 to 15 years, from the T-D2 / Commercial Tankless up to the T-KJr2 / T-KJr3 Indoor Tankless. Parts are covered for up to 5 years and labor for up to 1 year.
Can I transfer a Takagi tankless warranty to a new owner?
No. Takagi warranties are not transferable. Warranty is for the original purchaser and installation address only.
How do I check whether my Takagi tankless is still under warranty?
Decode your serial number with our free tool at WaterHeaterChecker.com to find the manufacture date, then compare it against the coverage for your line (T-KJr2 / T-KJr3 Indoor Tankless, T-K4 / T-H3 Outdoor Tankless, and T-D2 / Commercial Tankless). You can also call Takagi at 888-882-5244 with your serial number.
What voids a Takagi tankless warranty?
Common warranty voiding issues for Takagi include: Improper installation; Scale and lime buildup from hard water without treatment; Lack of annual maintenance.
Does Takagi sell an extended warranty for the T-KJr2 / T-KJr3 Indoor Tankless, T-K4 / T-H3 Outdoor Tankless, and T-D2 / Commercial Tankless?
The T-KJr2 / T-KJr3 Indoor Tankless, T-K4 / T-H3 Outdoor Tankless, and T-D2 / Commercial Tankless carry only the standard Takagi factory warranty shown above; no separate extended plan is listed. Ask about dealer coverage when you call 888-882-5244.
What should I do if my Takagi tankless fails under warranty?
Register your product at takagi.us.com. Then contact Takagi customer service at 888-882-5244. The Takagi warranty line is 888-882-5244.
More for Your Takagi Water Heater
Not sure which of Takagi's 3 lines you have?
Coverage differs across Takagi's lines, so decode your serial number to find the manufacture date and match it to the right 3-line warranty range above.
Decode Your Takagi Serial NumberThe 3 coverage figures shown above were last verified in March 2026 and are provided as a helpful reference only. Warranty terms are set by Takagi and may change at any time. Always refer to the warranty certificate that came with your water heater for the definitive terms of your coverage. WaterHeaterChecker.com is not affiliated with Takagi or A.O. Smith Corporation.