Lochinvar NOBLE/KNIGHT and Navien NCB are the two dominant condensing combi boiler platforms in the US residential market. Both are stainless fire-tube designs at 95% AFUE, but they differ on warranty, controls, and contractor support patterns.
Side-by-side
| Lochinvar NOBLE / KNIGHT | Navien NCB-E / NCB-H | |
|---|---|---|
| AFUE | 95% | 95% |
| Turndown | 10:1 | 10:1 (newer NCB-H) |
| Heat exchanger | Stainless fire-tube | Stainless fire-tube (dual on some models) |
| Heat exchanger warranty | 5-yr NOBLE / 10-yr KNIGHT | 10-yr (residential) |
| DHW capacity (volume model) | 5.4 GPM (NKC199) | 5.7 GPM (NCB-H 240) |
| Smart controls | SMART TOUCH; Lochinvar app | NaviLink Wi-Fi |
| Parent company | AO Smith | KD Navien (Korea) |
| Contractor base | Plumbing-heating contractors; established | Wider; sometimes general plumbers |
Where Lochinvar leads
- Hydronic heating-and-DHW expertise — Lochinvar contractors typically specialize in boilers; Navien install often by general plumbers
- KNIGHT 10-year heat exchanger warranty — matches Navien at the residential tier
- SQUIRE indirect ecosystem — Lochinvar has the strongest indirect tank lineup if you outgrow the combi
- Cascade capability for larger homes / light commercial
- SMART TOUCH controls have superior diagnostics for contractor service
Where Navien leads
- Slightly higher DHW flow on equivalent BTU sizes
- NaviLink Wi-Fi app is more mature than Lochinvar\'s connectivity
- Wider contractor availability — easier to find an installer in many markets
- Lower upfront cost typical $200-500 less at equivalent sizing
- 10-year heat exchanger warranty standard (matches KNIGHT, beats NOBLE)
Annual service for both
Both require annual professional service for warranty. Both have plate heat exchangers that scale in hard water. Both need combustion analysis after major service. Service expense is comparable ($300-450/year).
Reliability patterns
Field reports favor Lochinvar in heating-dominant cold climates (Northeast, Upper Midwest) where contractor expertise and SQUIRE indirect pairing matter most. Navien fares well in moderate climates and where simpler installs prevail. Both fail similarly when annual service is skipped.
Which to choose
- Cold climate + serious hydronic system + want SQUIRE option later: Lochinvar
- Moderate climate + standard install + want Wi-Fi controls: Navien
- Best contractor relationship matters most: use whichever your trusted installer prefers
- Want longest warranty without paying premium: Lochinvar KNIGHT (10-yr) or Navien NCB-H (10-yr) — tied
Bottom line
Both are top-tier combi boilers. Lochinvar wins on contractor expertise and indirect ecosystem; Navien wins on availability and DHW flow. Contractor relationship is the deciding factor more often than the product itself.