The Greentherm series is Bosch's flagship gas tankless line. Built around stainless heat exchanger with the longest warranty in the residential gas tankless category (15 years on condensing models).
Greentherm lineup
| Model | BTU | GPM | Type | Warranty (HE) |
|---|---|---|---|---|
| Greentherm 9999 SE | 199k | 11.0 | Condensing, Wi-Fi built-in | 15 years |
| Greentherm 9900 SE | 199k | 10.6 | Condensing | 15 years |
| Greentherm 9000 | 199k | 9.9 | Condensing | 15 years |
| Greentherm 5300 | 120k | 5.3 | Condensing | 10 years |
| Greentherm 7.2 | 180k | 7.2 | Non-condensing | 10 years |
Outdoor variant (9000-OD) and propane variants (9000-LP, 5300-LP) available.
Which Greentherm is right?
- 3-4 bath flagship: Greentherm 9999 SE (newest, Wi-Fi built-in)
- 3-bath volume: Greentherm 9900 SE or Greentherm 9000
- 2-bath: Greentherm 9000 or 9900 SE in cold climates; 7.2 if PVC venting is difficult
- 1-2 bath warm climate: Greentherm 5300
- Non-condensing requirement: Greentherm 7.2 (stainless Category III venting)
Warranty
15 years heat exchanger (condensing) / 5 years parts / 1 year labor. Among the best in the residential gas tankless category.
Bottom line
For homes choosing Bosch on the gas tankless side, Greentherm 9999 SE or 9900 SE are the flagships. Greentherm 9000 is the value condensing pick. Greentherm 5300 for small homes. The 15-year heat exchanger warranty is the strongest selling point.