John Wood Noritz Concentric Vent - NR98-DVC (N-0751M) - Manual (Page 18)

18
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.
Water Treatment
Water Treatment System
City Water Supply
Cold to Water
Heater
Optional Sediment
Filter
Water Treatment Device
Shutoff Valve
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)
ScaleShield Once a Year Once a Year
Twice a Year
Once a Year
7-10 gpg
(120-171 mg/L)
ScaleShield
Very Hard
10-14 gpg
(171-239 mg/L)
Water
Softener
Softener
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)
Water
Softener
Softener
Required
Water
Softener
Softener
Required
Water
Softener
Softener
Required
* Install Noritz Isolation Valves to allow for flushing.
Water
Softener
Suggested
Water
Softener
Suggested
**
**
*Install Noritz Isolation Valves to allow for flushing.
**Flushing is required if a water softener is not installed.
Residential Use Treatment Guidelines Commercial Use Treatment Guidelines
Pressure
Relief
Valve
Hot Water to Fixtures
Shutoff Valve
Drain
NORITZ
N-0751M-DVC