DDC Controls Package Manual VHC-36, -42 and -50 Operation Instructions Manual Model: VHC-36, VHC-42, VHC-50 ©2009 Venmar CES Inc.
Table of Contents Overview...............................................................................................................................................................................3 Features and Benefits..........................................................................................................................................................3 Terminal Strip......................................................................................................................
Overview The DDC control package is programmed for a range of temperature control and scheduling modes which are field selectable. The control package enables the VHC to control discharge air temperature, room/return air temperature or discharge in conjunction with room air temperature based on sensor readings. It can also be used to control the amount of air being recirculated back into the building.
Control Details Stand Alone Operation The DDC control package includes a four-button user interface called the BacStat II. This device can be mounted anywhere and when room air tempering is needed, can be configured as a room thermostat. A wide range of configuration options are included and can be accessed through the BacStat (see Figure 2). For stand alone operation an external dry contact (ex: remote time clock, CO2 sensor or manual selector switch, etc.
being used then you must not provide any jumpers to terminals 304, 305, 306, 307 or 308. The remote unit control multi-state variable is used to enable the unit through a Bacnet interface. Set MV12 to: • • • • 2 for unoccupied mode. 4 for occupied recirculation mode (optional). 6 for unoccupied recirculation mode (optional). 10 for ventilation mode. Temperature Control Configuration The VHC unit can be configured to control building temperature a variety of ways.
Adjust the following setpoints: #147 – Summer Zone Setpoint • Limits: 60–80°F [15–25°C] • Factory set: 70°F • BACnet variable: AV84 • Function: The summer zone setpoint is the room or return air setpoint for summer mode. #150 – Winter Zone Setpoint • Limits: 60–80°F [15–25°C] • Factory set: 70°F • BACnet variable: AV87 • Function: The winter zone setpoint is the room or return air setpoint for winter mode.
VHC Sequence of Operation Ventilation IMPORTANT The following conditions may not occur in the exact order as listed. On a call for occupied ventilation (occupancy contact closed): • • • • • • Wheel starts (not in free cooling). Recirculation damper closes (if equipped). Exhaust air damper opens. Outside air damper opens. After exhaust air damper opens; exhaust blower starts. After outside air damper opens; supply blower starts. #105 – Summer Span • Limits: 1–8°F [0.
Adjust the following setpoints: #124 – Enthalpy Free Cooling Setpoint • Limits: 10–70 Btu/lbs [23–163 Joules/Gram] • Factory set: 20 Btu/lbs • BACnet variable: AV45 • Function: The enthalpy free cooling setpoint is the measured enthalpy that the unit will go into free cooling. #125 – Enthalpy Free Cooling Span • Limits: 5–20 Btu/lbs [11–46 Joules/Gram] • Factory set: 5 Btu/lbs • BACnet variable: AV46 • Function: The enthalpy free cooling span is the differential above and below the free cooling setpoint.
ing air temperature setpoint, after staging delay, second compressor starts. This process continues until the (return) room air temperature is satisfied. Dx Cooling, WSHP Cooling, Two Compressors, First Compressor VRC® (Room Air Temperature Control) If outside air temperature is above summer setpoint (selectable), and if (return) room air temperature rises above summer zone setpoint and coil leaving air is above coil leaving setpoint, first compressor starts and modulates to maintain setpoint.
WSHP Heating, One Compressor, Optional VRC® (Discharge Air Temperature Control) WSHP Heating, Two Compressors, First Compressor VRC (Room Air Temperature Control) If outside air temperature is below summer setpoint (selectable), and if coil leaving air temperature rises above heating setpoint (selectable), first compressor starts. Modulate compressor to heating setpoint. Additional postheat will heat up supply air if heating setpoint cannot be maintained (if equipped).
Frost Control (Selectable) Preheat Frost Prevention Recirculation Defrost If the outside air temperature is below the frost control setpoint (selectable), frost control is enabled. If the outside air temperature is below the frost control setpoint (selectable), frost control is enabled. Frost control timing varies depending upon strategy selected. • • • • • Outside air damper closes. Recirculation damper opens. After delay, exhaust air damper closes and exhaust blower stops.
The middle characters represent the mode the unit is in: ‘Un’ = ‘Ov’ = ‘Or’ = ‘Ur’ = Unoccupied. Occupied ventilation. Occupied recirculation. Unoccupied recirculation. The bottom characters represent the supply air cooling/ heating setpoint. If the zone configuration is set to discharge air control (MV11= NO) and the unit has hot gas reheat, then this will display the cooling setpoint in summer mode and the heating setpoint in the winter mode.
Appendix A: Control Wiring Connections Example 1. Complete wire connections between the unit and the exhaust air damper by matching the correct wire colors on the actuator and end switch with the wire colors on the schematic before installing (ACT4004, if applicable). 2. The supply air temperature sensor (SN3002) is included loose in the unit and can be found in the control panel. Install the temperature sensor a minimum of 12 feet downstream of the unit.
#1 R3006 10K From 3000 24 VA+ Option free cooling (D) − 0 3023 SN3022 return air humidity sensor + − 3022 SN3019 outside air humidity sensor 0 Option free cooling (S or D) From 3001 24 VA− 3020 3024 PNL 310 BK W R BK W R SHLD CBL SHLD CBL PNL 310 PNL 301 PNL 301 R3014A 4.99K ACT4004 PNL R3014 309 10K FW 306 FW 306 #2 R3006B 2.49K PNL 311 R3018 2.49K PNL 311 FW 307 R3006C 1.24K PNL 311 R3018A 1.
VCES-DDC-IOM-1C 4024 4023 4022 4021 4020 4019 4018 4017 4016 4015 4014 4013 4012 4011 4010 4009 4008 4007 4006 4005 4004 4003 4002 4001 4000 From 3005 NET 2− From 3004 NET 2+ From 3003 DDC 24 VAC− From 3002 DDC 24 VAC+ SN4021 Cooling leaving air temperature sensor PNL 337 V PNL 336 R BR BL GY 0 COM NO recirc damper actuator COM NC recirc damper actuator CR3017 CR3017 COM NO EA damper actuator COM NC EA damper actuator CR3015 CR3015 COM NO actuator OA damper Optio
VCES-DDC-IOM-1C RH1 On/off BAC Prg Dpr Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp 6 7 8 9 10 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 Coil leaving reset Coil leaving span Coil leaving setpoint Heat off minimum Heating reset Heating span Heating setpoint Cool off minimum Cooling reset Cooling span Cooling setpoint Summer reset Summer span Summer setpoint Low limit delay Low limit setpoint High limit s
VCES-DDC-IOM-1C 17 Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 Item # Description 40°F–65°F [4°C–18°C] Limits 50°F Factory Set On/off On/off −5°F–50°F [−20°C–10°C] 2°F–10°F [1°C–5°C] 0–100% 0–100% 40°F–80°F [5°C–27°C] 4°F–20°F [2°C–12°C] 0–100% 5–20 Btu/lbs 50°F–105°F [10°C–40°C] 4°F–20°F
VCES-DDC-IOM-1C 18 Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp Stp N/A 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 199 N/A Remote unit control AV152 50% 2°F 70°F 50% 2°F 70°F AV27 AV26 N/A °F 35°F Off 65°F MV12 BV99 AV185 BV145 AV180 90 seconds AV19 Off BV141 100°F 50°F MV11 AV89 AV88 AV87 AV86 AV85 AV84 This setting is used to change from Stan
Appendix C: Standard Network Practice Unit Control The unit can be enabled in ventilation mode by jumpering FW 304 to 305. Alternatively the software point MV12 can be used to schedule the unit. If this method is being used then you must not provide any jumpers to terminals 304, 305, 306, 307 or 308. The remote unit control multi-state variable is used to enable the unit through a Bacnet interface. Set MV12 to: • • • • 2 for unoccupied mode. 4 for occupied recirculation mode (optional).
− − IMPORTANT + + Note that DNT294 Network Terminators are not provided by Venmar CES. 1 2 Shielding and Grounding Figure C6 shows preferred shielding and grounding methods. GND P1 − DNT294 Rev 1.1 Delta © 04/00 + − + − + RS485 port RS485 network terminator A maximum of 32 nodes are allowed on a single daisy chain segment. A node is defined as any device (Panel, Zone, Repeater, etc.) connected to the RS485 network. Terminators do not count as a node.
Appendix D: DDC Troubleshooting Guide All DDC units come with a “BacStat” which can act as a room thermostat where you can change the heating setpoint, cooling setpoint, summer setpoint and many more. The BacStat will act as a remote panel and should be looked at first when there is any issue with the unit. The supply air sensor also functions like a low limit sensor. This is not to be confused with the “LL” alarm indicated above.
Table D3: DDC Troubleshooting Guide Problem Cause Occupancy contact open. Solution Check contact closure between field wiring terminals 304 and 305 (see wiring schematics in the VHC-36, 42 and 50 IOM for wiring details). Check the BacStat shows ‘OV’ for occupied ventilation. BacStat will flash ‘OL’ in the upper left corner. Check motor overload trip indicator on overload relay (located Blowers are overloaded. below contactor). If it has tripped, press the reset button.
Table D3: DDC Troubleshooting Guide Problem Exhaust fan will not turn on. Cause Unit is in recirculation defrost (units equipped with recirculation defrost). Unit is in unoccupied recirculation (units with recirculation damper). Damper end switches are not making. Damper will not open. Electrical supply interrupted. Supply fan will not turn on. Unit is in exhaust defrost (units equipped with exhaust defrost). Damper end switches are not making. Solution BacStat will flash ‘dF’ in upper left corner.
info@venmarces.com www.venmarces.com Venmar CES Inc. has a policy of continuous improvement and reserves the right to change design and specifications without notice. ©2009 Venmar CES Inc.
