14
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
Condensing
Tankless Gas
Water Heater
Water Treatment System
Type of Water
Hardness Level Treatment Device*
Flush Frequency**
Soft
0-1 gpg
1-3 gpg
(0-17 mg/L)
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*** or
Flashing the error code****
Once a Year*** or
Flashing the error code****
Once a Year*** or
Flashing the error code****
Once a Year*** or
Flashing the error code****
7-10 gpg
(120-171 mg/L)
Very Hard
10-12 gpg
(171-200 mg/L)
H2Flow or
Water Softener
H2Flow or
Water Softener
Extremely
Hard
> 12 gpg
(> 200 mg/L)
* When selecting a treatment device, you must
consult with the device’s spec sheet and
installation manual for guidelines and limitations.
Not all water supplies are compatible -
a water test may be required.
** Install Noritz Isolation Valves to allow for flushing.
***
Flushing is required if a water treatment
device is not installed.
**** The error code "
㻯㻌㻌㻌㻏
" will be flashing in the
Display Window.
= 1, 2, 3, 4, F
# = 1, 2, 3, 4, 5, 6, 7, 8, 9, A, b, C, d, E, F
Residential Use Treatment Guidelines
Water Treatment
▲The illustration is an example. Please check with the actual water heater about the position of piping, and form.
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. If this
water heater will be installed in an application where the supply water is hard, Scale Build-up may cause
damage to the Heat Exchanger. In this case, this water heater detects Scale Build-up in the Heat
Exchanger and then the error code "
"* will flash in the Display Window. When the error code "
"*
is displayed, the Heat Exchanger needs to be flushed to prevent damage from Scale Build-up. Refer to the
"Procedure for flushing the Heat Exchanger" on page 15 or contact Noritz America for more information.
(http://support.noritz.com/ or 866-766-7489)
Damage to the water heater as a result of the items below is not covered by the Noritz America Limited
Warranty.
• Water in excess of 12 gpg (200mg/L) of hardness
• Poor water quality (See the Water Quality List on page 13.)
• The water heater has displayed a "
" error code indicating Scale Build-up, but the heat exchanger
has not been flushed.
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 http://support.noritz.com/ or 866-766-7489.
*
= 1, 2, 3, 4, F
# = 1, 2, 3, 4, 5, 6, 7, 8, 9, A, b, C, d, E, F
