13
Water Treatment System
City Water Supply
Pressure
Relief
Valve
Hot Water to Fixtures
Shutoff Valve
Drain
Cold to Water
Heater
Optional Sediment
Filter
Water Treatment Device
Shutoff Valve
NORITZ
Tankless Gas
Water Heater
Type of Water
Hardness
Level
Treatment
Device
Flush
Frequency*
Type of Water
Hardness
Level
Treatment
Device
Flush
Frequency*
Soft
0-1 gpg
1-3 gpg
(0-17 mg/L)
None
None
None
None
None
None
Slightly Hard
(17-51 mg/L)
None
None
Moderately
Hard
Hard
3-7 gpg
(51-120 mg/L)
H2Flow or
ScaleShield
H2Flow or
ScaleShield
Once a Year**
Once a Year
Twice a
Year
Once a Year**
7-10 gpg
(120-171 mg/L)
Very Hard
10-14 gpg
(171-239 mg/L)
H2Flow
H2Flow
H2Flow
H2Flow
H2Flow
H2Flow
Treatment
Required
Extremely
Hard
Soft
Slightly Hard
Moderately
Hard
Hard
Very Hard
Extremely
Hard
> 14 gpg
(> 239 mg/L)
0-1 gpg
1-3 gpg
(0-17 mg/L)
(17-51 mg/L)
3-7 gpg
(51-120 mg/L)
7-10 gpg
(120-171 mg/L)
10-14 gpg
(171-239 mg/L)
> 14 gpg
(> 239 mg/L)
Treatment
Required
Treatment
Required
Treatment
Required
* Install Noritz Isolation Valves to allow for flushing.
** Flushing is required if a water treatment device is not installed.
Suggested
Suggested
**
**
* Install Noritz Isolation Valves to allow for flushing.
** Flushing is required if a water treatment device is not installed.
Residential Use Treatment Guidelines
Commercial Use Treatment Guidelines
Water Treatment
If this water heater will be installed in an application where the supply water is hard, the water must be
treated with either the Noritz H2Flow or ScaleShield or a water softener. Refer to the below tables for
suggested treatment and maintenance measures to be taken based on the water hardness level.
Damage to the water heater as a result of water in excess of 12 gpg (200 mg/L) of hardness is not
covered by the Noritz America Limited Warranty.
Note: Water softeners may be regulated by the local water jurisdiction, consult with the manufacturer
for code, sizing, and installation guidelines; the below diagram is for reference only. For more
information about H2Flow and ScaleShield, contact Noritz America at 866-766-7489.
