Radiant
VAV Heated Floor
The system is composed of high temperature radiant heating panels in the floor of the space and has no mechanical cooling capabilities.
System Simulation
When the room drift temperature falls below the hourly heating thermostat, the heat source is activated to maintain the room at the heating thermostat temperature. When the drift temperature rises above the room heating thermostat, the room temperature is allowed to drift upward.
System Options
1. Outside air is brought into the space via a separate outside air system. The value of minimum outside air airflow will be proportional to the percentage defined by the outside air schedule. Economizer controls are not available to the Heated Floor system; however, opening and shutting of windows can be simulated (even if there are no external walls) by specifying a dry bulb economizer type and scheduling the economizer available during occupied hours.
2. The only fan allowed to operate is the optional ventilation fan which will follow the outside air schedule in time clock fashion, i.e., if the schedule reads 80% for a particular hour, the fan will operate at full rpm for 80% of the hour and remain off the rest of the hour.
3. Reset Schedule. The radiation system responds only to the room heating thermostat and will thus ignore any OA reset schedule.
Application Notes
● If radiant panels are used as the heat source, the user should set back the heating thermostat several degrees from normal (for example, from 68 to 65 F) since radiant panels are able to maintain an equivalent comfort level at a lower room air temperature.
● Internal rooms (no walls, roofs, etc.) should be provided with adequate outside air to temper the room temperature if internal loads are scheduled; otherwise, the room temperature may go out of control.
● Since the ventilation air brought into the room will create "positive" building pressure, it is suggested that infiltration be scheduled opposite the outside air schedule, e.g., for outside air scheduled at 40% for a particular hour, the infiltration schedule should read (100 - 40) = 60%.
● A radiation system can support a plenum, but any loads assigned to return air will be conducted back out through the ceiling and any external plenum (wall and roof) surface areas.
VAV Chilled Ceiling
The system is composed of radiant panels in the ceiling of the space and has no mechanical heating capabilities.
System Simulation
When the room drift temperature rises above the hourly heating thermostat, the cooling panels are activated to maintain the room at the cooling thermostat temperature. When the drift temperature falls below the room cooling thermostat, the room temperature is allowed to drift upward.
System Options
1. Outside air is brought into the space via a separate outside air system. The value of minimum outside air airflow will be proportional to the percentage defined by the outside air schedule. Economizer controls are not available to the radiant cooling system; however, opening and shutting of windows can be simulated (even if there are no external walls) by specifying a dry bulb economizer type and scheduling the economizer available during occupied hours.
2. The only fan allowed to operate is the optional ventilation fan which will follow the outside air schedule in time clock fashion, i.e., if the schedule reads 80% for a particular hour, the fan will operate at full rpm for 80% of the hour and remain off the rest of the hour.
3. Reset Schedule. The radiation system responds only to the room cooling thermostat and will thus ignore any OA reset schedule.
Application Notes
● Internal rooms (no walls, roofs, etc.) should be provided with adequate outside air to temper the room temperature if internal loads are scheduled; otherwise, the room temperature may go out of control.
● Since the ventilation air brought into the room will create "positive" building pressure, it is suggested that infiltration be scheduled opposite the outside air schedule, e.g., for outside air scheduled at 40% for a particular hour, the infiltration schedule should read (100 - 40) = 60%.
● A radiation system can support a plenum, but any loads assigned to return air will be conducted back out through the ceiling and any external plenum (wall and roof) surface areas.