Raypak 5000.72A, Инструкция по установке и эксплуатации

Страница: 46 / 80

46
Freeze Protection
This feature (when enabled via DIP switch #7 on the
PIM™ being set to ON) will cycle the boiler pump on if
either the inlet or outlet heater sensors drops below
45°F. The pump will continue to operate until the tem-
perature rises above 50°F at both sensors. If the
temperature continues to drop below 38°F at either
sensor, the heater will enable a heating cycle to oper-
ate at minimum firing rate to raise the water
temperature in the boiler to avoid freezing. The heat-
ing cycle will terminate when both the Inlet and Outlet
temperatures rise above 42°F.
Should the heater be in a soft lockout condition, the
Freeze Protection operation will over-ride all soft lock-
out timers to operate – however, it will NOT override a
hard lockout.
Freeze protection is functional with the VERSA IC
®
Control operator, but will also function in “limp-along”
mode should the VERSA IC
®
Control not be function-
ing, as long as the PIM™ DIP switch #7 is ON.
Rotation
When configured for cascade operation the VERSA
®
Master can be usre-defined to provide lead rotation.
Lead rotation, when selected via VERSA
®
DIP #6, is
fixed at 48 hours of burner run time as measured
between the lead unit and any other cascade member
run time. Once there is 48 hours difference in burner
run time between the lead unit and another cascade
member the lead will rotate to the unit with the least
amount of burner run time once the current call for
heat is satisfied. The remaining units will be operated
sequentially based on their order within the cascade.
Another feature of the rotation function is to force a
rotation event to occur after 60 hours of the lead stage
operating continuously due to a continuous call for
heat from the system. In the event that the lead unit is
not allowed to cycle off due to a continuous demand,
the VERSA
®
will force the cascade to achieve “target
+ differential” by increasing the firing rate of the active
unit until the system temperature is satisfied. Once the
system temperature is satisfied the active unit will
cycle off. This will in turn allow the rotation event to
occur to ensure equalized runtime of the cascade
members.
Target Differential – Auto/Manual
The VERSA IC
®
control system is configured as stan-
dard with an “Auto Differential” feature (H models
only). This function serves as part of how the controller
attempts to achieve a minimum ON time to ensure
maximum system and boiler operating efficiency. The
Warm Weather Shut Down (WWSD)
When the outdoor air temperature rises above the
WWSD setting, the VERSA IC
®
Control turns on the
WWSD segment in the display. When the Control is in
Warm Weather Shut Down, the Control does not oper-
ate the heating system to satisfy any heating demand
– however, any water heating or indirect heating load
will override the WWSD function until such call-for-
heat is satisfied. This value is only available to
set/change when the PIM™ identity is “H” and the
TARGET = RSET. The range of adjustments is from
40°F to 100°F or OFF. The default value is 70°F. The
lowest target calculation will be truncated based on the
Target Min Setting.
Reset Ratio
The VERSA
®
control uses the following four settings
as shown to calculate the Reset Ratio (RR):
For example, when using the default values, the RR is:
RR = (70 - 10) / (180 - 70) = 0.55
Pump and CWP Exercise
This feature (when enabled via DIP switch #4 on the
PIM™ is set to ON) will cycle the pumps and CWP, if
enabled, for 10 seconds every 72 hours, even with no
heat demand, to help extend the life of the pumps.
During this operation, the word “EXERCISE” will dis-
play on the VERSA IC
®
Display.
70°F
Decreasing Outdoor Temperature
70°F 10°F
180°F
Fig. 33: Outdoor Air Reset Curve
NOTE: WWSD has a differential of 2°F. Ensure the
proper installation of the outdoor air sensor to pre-
vent short cycling.
RESET RATIO (RR) =
BOILER DESIGN — BOILER START
OUTDOOR START — OUTDOOR DESIGN