Raypak 910500 Owner's Manual And Installation Instructions page 98

Water Heater Design (Boil DESIGN)
The Boil DESIGN temperature is the water temperature required to heat the water heater zones when
the outdoor air is as cold as the OUT DESIGN temperature.
Warm Weather Shut Down (WWSD)
When the outdoor air temperature rises above the WWSD setting, the control turns on the WWSD
segment in the display. When the control is in Warm Weather Shut Down, the Dem 1 segment is
displayed if there is a heat demand. However, the control does not operate the water heater to satisfy
this demand. The control continues to respond to DHW demands (if in Mode 2 or 3 - indirect DHW)
Reset Ratio
The controller uses the following four settings to calculate the Reset Ratio (RR):
For example, when using the default values, the RR is:
RR = (21 – (-12)) / (82 - 21) = 0.55
Therefore, the RR is 0.55:1 (Outdoor: Water).
Fig X: Reset Ratio
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