EZ Plate™ Storage Water Heater
17
PV500-64 12/14
8.5 Heat
Exchanger
Lime and scale deposited in the heat exchanger will result in an increase in pressure drop, lower temperature
difference on the domestic water side or a high exit temperature on the boiler water side. Cleaning and flushing can
be done without removing the heat exchanger from the system. There are threaded cleaning ports near the hot water
outlet and cold water inlet of the heat exchanger.
The frequency of cleaning (descaling/deliming) will be determined by the rate of scale buildup. Until the appropriate
cleaning interval is established, it is recommended that the heat exchanger be internally cleaned every six months or
more frequently if higher scaling conditions become apparent. Factors that may affect the rate of scale buildup are
the amount of hot water used and the temperature of the water. The more hot water used, the more fresh water
containing scale-forming compounds is brought into the heat exchanger. As the temperature of water increases, the
rate of scale deposition will increase.
The heat exchanger is provided with isolation shutoff valves to allow for quick isolation of the heat exchanger from
the system, and clean-in-place (CIP) fittings for chemical descaling without removing the heat exchanger from the
plumbing system. Close the isolation valves to the tank and cold water/recirculation inlet. With the heat exchanger
properly cooled and depressurized, remove the plugs from the CIP fittings.
The heat exchanger is cleaned by flushing with a suitable food grade acid detergent or biodegradable descaler,
available at most plumbing supply outlets:
• Isolate the heat exchanger from the hot boiler water and close the tank water isolation valves located near the
heat exchanger domestic water inlet and outlet. Allow the heat exchanger to cool before cleaning.
• Install a hose connection to the threaded cleaning ports.
• Prepare a 50% dilution of a commercial descaler in open container.
• Place a submersible utility pump into the descaler solution.
• Connect a hose from the pump to the lower cleaning port.
• Connect a second hose from the upper cleaning port to the descaler solution.
• Circulate through the heat exchanger and check the effectiveness of the solution visually and pH test.
• Flush system after cleaning.
• Remove all hoses from the CIP fittings, close the valves and replace the plugs.
• Open the tank water isolation valves located near the heat exchanger domestic water inlet and outlet.
• Follow the section titled “Start-Up and Shut-Down Procedure” to properly bring the water heater back online.
If needed, the double-wall exchanger can be mechanically cleaned. See the supplemental instructions provided by
the heat exchanger manufacturer. After cleaning the heat exchanger, clean the Y-strainer in the domestic water pipe
near the circulator pump.
Heat Exchanger Clean-In-Place Fittings
