The Watts OFTWH OneFlow Anti-Scale System protects tankless water heaters from scale buildup without salt, chemicals, or electricity. This 10 GPM cartridge system transforms hard water minerals into harmless microscopic crystals that flow through your plumbing without adhering to surfaces.
SPECIFICATIONS
Watts OFTWH Technical Details
| Model Number | Watts OFTWH (OneFlow Anti-Scale Tankless) |
| Maximum Flow Rate | 10 GPM |
| Connection Size | 3/4" Female NPT |
| Maximum Temperature | 100°F |
| Cartridge Lifespan | 2 years minimum |
| System Type | Single cartridge, template-assisted crystallization |
| Application | Cold water line protection for tankless water heaters |
| Bypass Valve | Required (sold separately) |
INSTALLATION & USE
Setup & Maintenance
- Install the Watts OFTWH on the cold water line directly before your tankless water heater. Do not install on the hot water side or after the heater.
- Plumb the system with a bypass valve to allow isolation of the filter housing during cartridge replacement or maintenance.
- Ensure water temperature entering the system does not exceed 100°F. The OneFlow media requires cold water to function properly.
- Replace the OneFlow cartridge every two years minimum to maintain effective scale protection, regardless of water volume processed.
COMPATIBILITY
System Requirements
The Watts OFTWH is designed specifically for single tankless water heater installations in residential applications. It requires a 3/4" NPT plumbing connection and must be installed on cold water supply lines only. This system works with all tankless heater brands and does not require electricity, drain lines, or regeneration cycles. The OneFlow technology is compatible with all water chemistry types but performs best when water temperature remains below 100°F at the inlet.
🔧 Pro tip: Install a pressure gauge before and after the OFTWH system to monitor differential pressure. A significant pressure drop indicates the cartridge is exhausted or fouled and needs replacement, even if the two-year service interval hasn't been reached.
