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AQUA PLUS indirect-fired water heaters — Product Manual
Troubleshooting
(continued)
Excessive domestic water temperature
1 Reduce stacking.
• Excessive water temperature is usually the result of stacking within the water heater.
• Stacking is the occurrence of various water temperatures layering within the water heater with the
hottest water in the uppermost layer.
• This layering or stacking effect typically occurs during small draws of hot water (typically less than
25% of the storage capacity) that are long enough to create a call for heat on the thermostat, but are
short enough not to deplete the stored energy within the tank.
• Excessive stacking can occur when frequent short-to-moderate draws are taken in quick succession.
• During this condition, the temperature of the domestic water can approach the temperature of the
boiler water.
• REMEMBER — All water heaters (direct or indirect) will stack.
• To reduce stacking within the tank:
• Reduce the boiler operating temperature to 160°F - 170°F. This will limit the maximum domestic
outlet water temperature during high stacking water usage.
2 Install a thermostatic mixing valve.
• Installing a thermostatic mixing valve will provide uniform delivery temperature with minimal regard
to water usage.
3 Install a recirculation loop.
• Installing a properly-sized recirculation loop not only provide prompt delivery of hot water, but it will
provide circulation and mixing of the water within the tank.
Part number GL-E223-ADOC 0311
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