AERCO Packaged WaterWizard Steam-to-Water Heater - Manual (Page 26)

HE-110
1B+ II Water Wizard Water Heaters
OMM-0063_0C Installation, Operation & Maintenance Manual
Page 26 of 50
MC2: 07/26/13 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 • Phone: 800-526-0288
CHAPTER 9. DE-SCALING BY THERMAL SHOCK METHOD
Where, under certain conditions of continuous steady usage, the Cold Water is so hard or
alkaline that normal flexure of the Heater coils (see Routine Maintenance) and routine blow
down (draining the Heater shell) will not remove scale buildup on the coils, the heating surfaces
(coils) may be thermally shocked, without damage to any part of the Heater, to dislodge scale
solids.
De-Scaling by Thermal Shock Instructions
1) Drain the Heater per steps 1 through 4, Chapter 6, ROUTINE MAINTENANCE, Chapter 6.
However, instead of holding the relief valve open in step 4, remove the relief valve, shown as
Item 73(A) in Figure 17 or 18 from the Heater top head.
2) Open the Heater drain valve. Leave the drain valve open until step 8 below.
3) Connect a source of cold water (for example, a hose from a cold water faucet) to the open
relief valve connection.
4) Open all shutoff valves in the Steam inlet line and the Condensate outlet line to allow Steam
to the Heater. After about 30 seconds, or until Steam is blowing out of the Condensate drain
line, close the stop valve in the Condensate outlet line. Leave the Steam inlet line open for
about two minutes longer, and then close all Steam inlet stop valves.
5) Inject a flow of cold water through the relief valve connection for about two minutes. Then shut
off the cold water flow and open the Condensate line stop valve to drain off all Condensate.
6) Repeat steps 4 and 5 several times until the water coming from the Heater drain appears to
be relatively free of solids.
7) Remove the cold water source from the relief valve connection. Open the stop valve in the
main Cold Water inlet line and allow a complete flushing of the Heater shell.
8) After the Heater shell has been completely drained, close the Heater drain valve, and place
the Heater back into operation per steps 1, 12, and 13 under OPERATING PROCEDURES,
Chapter 5.
9) If Cold Water conditions are so severe that thermal shocking does not remove scale deposits,
consult the nearest AERCO Representative for advice.