Noritz NC250-SV-ASME Manuel D'installation page 50

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 a water softener, which removes the hardness, or by using sequestering agents, such
as the Noritz Scale Shield, that reduce the amount of scale deposits. Refer to the below tables for sug-
gested 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: When installing a water softener, consult with the manufacturer for proper sizing and installation
guidelines; the below diagram is for reference only. For more information about Scale Shield, contact
Noritz America at 866-766-7489.
Residential Use Treatment Guidelines
Hardness
Type of Water Level
0-1 gpg
Soft
(0-17 mg/L)
1-3 gpg
Slightly Hard
(17-51 mg/L)
3-7 gpg
Moderately
Hard (51-120 mg/L)
7-10 gpg
Hard
(120-171 mg/L)
10-14 gpg
Very Hard
(171-239 mg/L)
Extremely > 14 gpg
Hard (> 239 mg/L)
* Install Noritz Isolation Valves to allow for flushing.
NORITZ
Tankless
Gas Water Heater
Pressure
Relief
Valve
Drain
50
Treatment Flush
Device Frequency*
None None
None None
ScaleShield Once a Year
Once a Year
ScaleShield
Water Softener
Softener Required
Water Softener
Softener Required
Water Treatment System
Cold to Water
Heater
Shutoff Valve
Hot Water to Fixtures
Commercial Use Treatment Guidelines
Hardness
Type of Water Level
0-1 gpg
Soft
(0-17 mg/L)
1-3 gpg
Slightly Hard
(17-51 mg/L)
3-7 gpg
Moderately
Hard (51-120 mg/L)
7-10 gpg
Hard
(120-171 mg/L)
10-14 gpg
Very Hard
(171-239 mg/L)
> 14 gpg
Extremely
(> 239 mg/L)
Hard
*Install Noritz Isolation Valves to allow for flushing.
**Flushing is required if a water softener is not installed.
Shutoff Valve
Optional Sediment
Filter
Water Treatment Device
Treatment Flush
Device Frequency*
None None
None None
Water
**
Once a Year
Softener
Suggested
Water
Softener
**
Twice a Year
Suggested
Water Softener
Softener Required
Water Softener
Softener Required
City Water Supply