30 November 1998
d. Incorporate system variations as required.
e. Replace "XX" in the drawing titles and unique identifiers with numbers specific to the project
HVAC control system.
f. For single-loop controller applications, modify HVAC control panel interior door layouts, back
panel layouts, and terminal block layouts as required. For DDC applications, modify data terminal strip
layouts as required.
g. Parameters shown in the equipment list must be modified to make the standard HVAC control
system drawings project specific.
h. Damper and valve position diagrams.
4. SPACE TEMPERATURE CONTROLLED PERIMETER RADIATION CONTROL SYSTEM.
a. Description of perimeter radiation system. This system consists of fin-tube radiation, a portion of
the hydronic heating system. Figure 4-1 shows the schematic and ladder diagrams and the equipment
schedule for this type of system.
Figure 4-1. Space temperature controlled perimeter radiation control system.
b. General sequence of operation. A room thermostat controls a perimeter radiation valve to
maintain a set temperature. The following options are available:
(1) Two-position thermostat with two-position valve.
(2) Microprocessor-based thermostat which cycles a two-position valve during the occupied
mode to maintain the programmed occupied mode setpoint, and during the unoccupied mode to maintain
the programmed unoccupied mode setpoint.
(3) A modulating thermostat with a modulating valve.
c. Detailed sequence of operation.
(1) In two-position control, the contacts of room thermostat T-XX01 close on a rise in
temperature to its setpoint, energizing normally-open valve VLV-XX01, which closes. On a fall in
temperature below its setpoint, the contacts of thermostat T-XX01 open, de-energizing valve VLV-XX01,
(2) In modulating control, thermostat T-XX01 modulates valve VLV-XX01 to maintain its
5. UNIT HEATER TEMPERATURE CONTROL SYSTEM.
a. Description of unit heater system. This system consists of a unit with a heating coil and a fan to
circulate air through a coil to provide heat to the space served. The heating coil is uncontrolled (no