CEMP-E
TI 811-12
18 August 1998
(2) Occupied Mode. The UMCS will modulate the secondary heating control valve when the
secondary zone pump is operating) to maintain the heating zone occupied space temperature setpoint.
(3) Unoccupied Mode. The UMCS will modulate the secondary heating control valve when the
secondary zone pump is operating) to maintain the heating zone unoccupied space temperature.
e. Steam/Hot Water Converter with Dual Temperature Distribution System Sequence of Operation
(1) All Modes. The UMCS will start and stop the distribution pump based on the signal from an
outside-air temperature sensor as shown. The UMCS will enable control of the steam/hot water converter
control valve when the distribution pump is operating and the system is in heating mode. When the
system is not in heating mode, control of the steam valve will be disabled. Heating and cooling modes
will be initiated by the UMCS and confirmed by monitoring the position of the changeover valves. UMCS
will not make the heating to cooling changeover until the return water temperature drops below 90
degrees F and will not make the cooling to heating changeover until the return water temperature raises
above 60 degrees F.
(2) Heating Mode. When the heating mode is selected, the system changeover valves will
close to the chilled water flow and will open to flow through the steam/hot water converter. The UMCS
will control the hot water supply temperature by modulating the steam control valve in response to a
temperature sensor in the hot water supply line to maintain its setpoint. The UMCS will reset the hot
water supply temperature setpoint with respect to the outside air temperature in a linear schedule as
shown.
(3) Cooling Mode. When the cooling mode is selected, the steam control valve will be closed,
the system changeover valves will close to the hot water flow and open to the chilled water flow. Chilled
water temperature control will remain under local controls.
f. High-Temperature Hot Water/ Hot Water Converter with Dual Temperature Distribution System
Sequence of Operation (Figure 8-6 and Table 8-6).
(1) All Modes. The UMCS will start and stop the distribution pump based on the signal from an
outside-air temperature sensor as shown. The UMCS will enable control of the high temperature hot
water/hot water converter control valve when the distribution pump is operating and the system is in
heating mode. When the system is not in heating mode, control of the high temperature hot water valve
will be disabled. Heating and cooling modes will be initiated by the UMCS and confirmed by monitoring
the position of the changeover valves. UMCS will not make the heating to cooling changeover until the
return water temperature drops below 90 degrees F and will not make the cooling to heating changeover
until the return water temperature raises above 60 degrees F.
(2) Heating Mode. When the heating mode is selected, the system changeover valves will
close to the chilled water flow and will open to flow through the high temperature hot water converter. The
UMCS will control the hot water supply temperature by modulating the high temperature hot water control
valve in response to a temperature sensor in the hot water supply line to maintain its setpoint. The
UMCS will reset the hot water supply temperature setpoint with respect to the outside air temperature in a
linear schedule as shown.
(3) Cooling Mode. When the cooling mode is selected, the high temperature hot water control
valve will be closed, the system changeover valves will close to the hot water flow and open to the chilled
water flow. Chilled water temperature control will remain under local controls.
g. Dual-Temperature System with Hot Water Boiler and Air-Cooled Chiller Sequence of Operation
8-3
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