Defender Safety System is Bradford White's volume FVIR-compliant atmospheric gas residential line. The signature feature is the intake air filter at the base of the unit — same design across all Defender models. 6-year warranty standard (10-year upgrade kit available through dealers).
The Defender lineup
- Defender 50G (M-I-504S6FBN) — the volume Bradford White install. For 3-4 person households.
- Defender 40G (M-I-404S6FBN) — for 2-3 person households.
What makes Defender different
- Bottom intake-air filter (requires annual cleaning — see cleaning guide)
- FVIR (Flammable Vapor Ignition Resistant) burner chamber
- Magnesium anode standard (aluminum-zinc upgrade available)
- Hydrojet... wait, no — that's AO Smith. Bradford White does NOT have a sediment management system.
- 6-year warranty (10-year upgrade kit available)
Defender vs Defender variants
- Defender (M-I-XXX4S6FBN) — base atmospheric gas with intake filter and FVIR burner
- ICON System (M2IXXX4T6FBN) — Defender + intelligent gas control with diagnostic LED
- Eco-Defender (M-IV-XXX6DS) — Defender + low-NOx burner for California SCAQMD compliance
Bottom line
Defender is what your Bradford White-network plumber installs by default for atmospheric gas. 6-year warranty, intake filter that needs annual cleaning, FVIR-compliant. Step up to ICON System for the diagnostic LED upgrade. For low-NOx jurisdictions step to Eco-Defender.