Weil-McLain Aqua Plus 35 Product Manual page 32

AQUA PLUS
INDIRECT
Troubleshooting
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.
32
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FIRED WATER HEATERS
(continued)
— Product Manual
Part number GL-E223-ADOC 0615