SmartPlate Installation, Operation & Maintenance Manual
CHAPTER 6
– SCHEDULED MAINTENANCE
OMM-0069_0H
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6.9 PERIODIC CLEANING OF HEAT EXCHANGER
It may be necessary to de-scale the heat exchanger periodically, depending on water conditions
and temperature settings. Section 8.2 describes the descaling process for the Water Heater
’s
heat exchanger.
The frequency of cleaning can be determined locally based on the performance of the heater
and/or prior experience with similar equipment. Generally, the cleaning requirements will follow
the trends shown in Table 6-2:
TABLE 6-2. Heat Exchanger Cleaning Guidelines
Operating Conditions
Projected Cleaning Frequency
Rarely
Annually
Semi-Annually
Monthly
Boiler Water Inlet Temp
<150ºF
~170ºF
~200ºF
~220ºF
Domestic Water Setpoint
<130ºF
140 - 160ºF
160 - 180ºF
Calcium Hardness Level
<20 mg/L
20 - 40 mg/L
40 - 60 mg/L
>80 mg/L
If calcium hardness level, boiler water inlet temperature, and domestic water setpoint fall under
different cleaning intervals in Table 6-2, the heat exchanger may be cleaned between those
periods, starting with the most frequent interval. During the next few cleaning intervals observe
how much scale is removed to determine if less frequent intervals can be followed.
Example:
BW inlet temperature = 180ºF
Domestic water setpoint = 140ºF
Calcium Hardness level = 40 mg/L
Heat exchanger Cleaning Frequency: Start out with semi-annually (every six months) schedule
(180ºF BW falls under semi-annually and the DHW setpoint and calcium hardness level fall
under annually). Observe the next few cleanings on how much scale is removed to determine if
an annual (yearly) cleaning frequency is more appropriate.
NOTE:
Refer to section 8.2 and 8.5 for heat exchanger maintenance procedure.
