Bosch Greenstar combi boilers compete with Lochinvar NOBLE/KNIGHT in the higher-end residential combi market. Bosch brings German engineering and brand recognition; Lochinvar brings established US contractor network.
Side-by-side
| Lochinvar NOBLE / KNIGHT | Bosch Greenstar | |
|---|---|---|
| AFUE | 95% | 95-96% |
| Turndown | 10:1 | 7:1 to 10:1 (model-dependent) |
| Heat exchanger | Stainless fire-tube | Aluminum-silicon (some models) |
| Heat exchanger warranty | 5-yr NOBLE / 10-yr KNIGHT | 10-yr (residential) |
| DHW (volume model) | 5.4 GPM (NKC199) | 4.4-5.6 GPM depending on Greenstar size |
| US contractor base | Wide and deep | Narrower; growing |
| Parts availability US | Wide | Narrower |
| Heritage | US, 1919 | German, established US presence |
Where Lochinvar leads
- Wider US contractor base — easier to find Lochinvar-trained installer
- Better parts availability nationwide
- Stainless fire-tube heat exchanger preferred by many US contractors over aluminum-silicon
- SQUIRE indirect ecosystem for hybrid combi/indirect installs
- Established US service network through plumbing-heating wholesalers
Where Bosch leads
- German engineering reputation — appeals to some buyers
- Slightly higher AFUE on some Greenstar models (96%)
- 10-year heat exchanger warranty standard (matches KNIGHT, beats NOBLE)
- Brand familiarity from Bosch appliances and tools
- European-style controls with sophisticated weather compensation
Heat exchanger material — the debate
- Stainless steel (Lochinvar): more corrosion-resistant in long-term, easier to service, US-preferred
- Aluminum-silicon (Bosch some models): faster heat transfer, lighter, sensitive to water chemistry. European-common
Stainless is the safer long-term choice in US municipal water that varies in chemistry. Aluminum-silicon requires more careful water-treatment attention.
US distribution gap
Bosch combi presence in the US has grown but remains limited compared to Lochinvar, Navien, and Weil-McLain. Many regions have no Bosch-trained combi installer within reasonable distance. If your installer doesn\'t routinely work on Bosch Greenstar, service quality is the risk.
Which to choose
- US install in a market with good Lochinvar contractor base: Lochinvar
- Bosch-trained contractor already established locally: Bosch is viable
- Want stainless heat exchanger specifically: Lochinvar (or verify the specific Bosch model)
- SQUIRE indirect pairing planned: Lochinvar single-brand
- German-engineering preference + good local install: Bosch
Bottom line
For US residential combi installs, Lochinvar\'s contractor base and parts availability give it the practical edge. Bosch Greenstar is a quality product but harder to service well outside markets with established Bosch contractor presence. Verify local install and parts support before choosing Bosch over Lochinvar.