Innovation - Edge [i] Installation, Operation, Maintenance Manual
CHAPTER 6
– MAINTENANCE
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9/6/2019
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6.2 WATER QUALITY GUIDELINE
To keep your water heater operating efficiently over a long lifetime, it is critical to make sure the
chemical composition of incoming water is not harmful to the heater. To prevent corrosion,
fouling, and other harmful effects on the heater, the following water quality guideline should be
adhered to:
Total dissolved solids are a measure of overall risk of water corrosivity/hardness/salinity/color.
The EPA recommends keeping a level below 500 ppm.
For calcium hardness limits, see Table 6-8 in Section 6.8.1, below. The allowable calcium
hardness depends on temperature set point as well as concentration.
Many water systems also carry orthophosphate chemicals for corrosion protection. These
chemicals form orthophosphate scale. Conventional water softening techniques that treat calcium
scale may not treat orthophosphate scale. If the system contains orthophosphates, the unit must
be inspected every 6 months and cleaned as needed. Systems may also contain polyphosphates
that sequester and mitigate water hardness. Over time, these chemicals break down in the
system to form orthophosphates. Therefore, any water entering the water heater that contains
polyphosphates warrants that the heat exchanger be inspected every 6 months and cleaned as
needed.
Chloride limits are set to prevent corrosion of the heat exchanger. The EPA also recommends
levels lower than 250 ppm for potable systems.
Free chlorine is added to systems to protect from harmful microbes. Most public water supplies
have been treated to a safe level, but care must be taken when building owners perform
supplemental treatment. Batch feeding or poorly controlled methods will cause free chlorine
spikes that will damage any equipment in the system. When added in excess, free chlorine is a
powerful oxidant that can cause corrosion. Inlet water fed to the heater should always be below
0.5 ppm free chlorine, regardless of where in the system the chemical feed pump is positioned.
6.3 IGNITER-INJECTOR
The igniter-injector (Kit P/N
58023
) is located on the flange of the intake manifold, at the bottom
of the unit’s heat exchanger. Figure 6.3-1 shows the intake manifold (removed from the unit)
showing the location of the igniter-injector, flame detector and gasket (Kit P/N
24356-2
) and other
related components.
The igniter-injector may be hot; therefore, care should be exercised to avoid burns. It is easier to
remove the igniter-injector from the unit after the unit has cooled to room temperature.
TABLE 6-2:
Water Quality Guideline
Total Dissolved Solids:
500 ppm
Hardness (CaCO
3
):
See Table 6-8, Section 6.8.1
Chlorides:
250 ppm
Free Chlorine
0.5 ppm