Trace 3D Plus
User Guide
 
C.D.S Support
×
All trademarks referenced are the trademarks of their respective owners.
© 2024 Trane. All Rights Reserved.
Version 1.3

Low Temperature Radiant Constant Flow (Cooling and/or Heating)

A Low Temperature Radiant panel is a zone level heating and/or cooling coil mounted in the floor, walls, and/or ceiling of the rooms. In TRACE 3D Plus, the Low Temperature Radiant Constant Flow equipment is zone level equipment that uses water to heat and/or cool a room surface (floor or ceiling). A constant flow system uses a separate zone level circulation pump to maintain constant flow.
A Ceiling Radiant Panel must be assigned to a zone that contains rooms with radiant layers in their ceiling construction. An In Floor Radiant Panel must be assigned to a zone that contains rooms with radiant layers in their floor construction.
The heating and/or cooling is controlled by varying the water temperature to the coil(s). The water temperature to the coil(s) is varied by the use of a three-way mixing valve upstream of the pump which allows a fraction of the return water to mix with supply water. The Low Temperature Radiant Constant Flow equipment uses a water loop from a separate plant and are not themselves directly heated by gas or electric: there are separate library members for Low Temperature Radiant Electric panels and High Temperature Radiant panels.
back to Zone Radiant and Convective top
 
Control Type
Default: Mean Air Temperature
Typical Range: N/A
Min Max:N/A
Units: N/A
The Control Type field specifies which parameter the Setpoint Temperature High Limit and Setpoint Temperature Low Limit fields represent. The Setpoint Temperature limits and the Water Inlet Temperature limits together control the constant flow radiant system. The Control Type field must be set to one of the following options:
  • Mean Air Temperature
  • Mean Radiant Temperature
  • Operative Temperature
  • Outdoor Dry Bulb Temperature
  • Outdoor Wet Bulb Temperature
 
Cooling Mode/Heating Mode
Low Temperature Radiant Constant Flow equipment may be configured as cooling only, heating only, or heating and cooling. The water flow rate is based upon the operating mode. If the unit operates in cooling only or heating only, the heating or cooling design flow rate is selected. If the unit operates in heating and cooling, the largest value between the heating design flow rate and the cooling design flow rate is selected.
 
Water Inlet Temperature High/Low limit
Default: 59°F/15°C (High), 50°F/ 10°C (Low)
Typical Range: 50° to 59°F / 10° to 15°C
Min Max: 75 to 120°F / 23.8 to 48.8°C
Units: °F/°C
The Water Inlet Temperature High and Low Limit fields specify the high and low limits for the mixed water temperature leaving the three-way valve and entering the coil(s). If the water temperatures from the plant and from the coil(s) are such that mixing water to meet these limits is not possible, an error will occur.
 
Setpoint Temperature High/Low Limit
Default: 79°F/26.11°C (High), 72°F/ 22.22°C (Low)
Typical Range: 72° to 79°F/22° to 26°C
Min Max: N/A
Units: °F/°C
The Setpoint Temperature High Limit and Low Limit fields specify the high and low limits for the temperature of the parameter specified in the Control Type field.
The Setpoint Temperature limits for the Control Type field and the Water Inlet Temperature limits together control the constant flow radiant system.The current temperature of the parameter specified in the Control Type field is compared to the Setpoint Temperature High Limit and Low Limit at the current time.
 
Control in Cooling Mode
  • If the current temperature of the parameter specified in the Control Type field is above the Setpoint Temperature High Limit, the mixed water temperature will be set to the Water Inlet Temperature Low Limit.
  • If the current temperature of the parameter specified in the Control Type field is between the Setpoint Temperature High Limit and Low Limit, the mixed water temperature will be modulated between the Water Inlet Temperature Low Limit and High Limit.
  • If the current temperature of the parameter specified in the Control Type field is below the Setpoint Temperature Low Limit, the water flow rate will be set to zero to shut down the pump and coil(s).
 
Control in Heating Mode
  • If the current temperature of the parameter specified in the Control Type field is below the Setpoint Temperature Low Limit, the mixed water temperature will be set to the Water Inlet Temperature High Limit.
  • If the current temperature of the parameter specified in the Control Type field is between the Setpoint Temperature Low Limit and High Limit, the mixed water temperature will be modulated between the Water Inlet Temperature High Limit and Low Limit.
  • If the current temperature of the parameter specified in the Control Type field is above the Setpoint Temperature High Limit, the water flow rate will be set to zero to shut down the pump and coil(s).
 
Secondary Pump
The secondary pump provides the water flow through the low temperature radiant coil(s). The pump will consume energy as it provides the water flow rate according to the inputs provided.
 
Full Load Power
Default: 50 W
Typical Range: N/A
Min Max: > 0 W
Units: W, kW, hp
The Full Load Power field specifies the total full load input power.
 
Pump Head
Default: 25 ft H2O
Typical Range: 5 to 36 ft H2O
Min Max: NA
Units: ft H2O, Pa, kPa
This field contains the pump’s rated head.
 
Motor Efficiency
Default: 80%
Typical Range: N/A
Min Max: 0 to 100%
Units: %
Enter the pump’s efficiency
 
Motor Heat to Fluid
Default: 0%
Typical Range: N/A
Min Max: 0 to 100%
Units: %
This field contains the pump’s percentage of power loss to the fluid.
back to Low Temperature Radiant top
 
 
Condensation
Control Type
Default: System Off
Typical Range: System Off, Moisture Control
Min Max: N/A
Units: N/A
When radiant systems do cooling, there is the possibility that condensation will occur on the surface that is being cooled. This is due to the fact that the surface temperature may drop below the dew-point temperature of the space which causes condensation to accumulate on the surface.
The Control Type field can be set to either No Moisture Control or System Off.
  • No Moisture Control – TRACE 3D Plus will nothing other than produce a warning message when condensation is predicted to occur. The program will continue: no moisture will be removed from the zone air and no adjustment will be made to the surface temperature as a result of the condensation.
  • System Off – TRACE 3D Plus will predict cases where condensation will occur and shut-off the radiant system to avoid this situation. With this option, the user has the ability to adjust when the system will shut down using the Dewpoint Range field.
 
Dewpoint Range
Default: 34°F/1.11°C
Typical Range: 50 to 59°F / 10 to 16°C
Min Max: 0 to 100°F / -17 to 38°C
Units: °F/°C
This optional parameter is only available when the System Off option is selected for the Control Type. It establishes the difference between the calculated dew-point temperature of the space and the allowed surface temperature to which the surface can drop before the radiant system shuts down. This parameter can be any positive, negative, or zero value. When this parameter is zero, the radiant system will shut down when the surface temperature drops to the dew-point temperature or below. When this parameter is positive, the radiant system will shut down when the surface is the number of degrees above the dewpond temperature; this allows some extra safety to avoid condensation. When this parameter is negative, the radiant system will shut down when the surface temperature is the number of degrees below the dew-point temperature. While not recommended, this strategy allows the user to simulate a situation where small amounts of condensation are tolerable.
 
Hydronic Tubing
Diameter
Default: 0.51 in/0.013 m
Typical Range: 50 to 59°F / 10 to 16°C
Min Max: NA
Units: ft, in/m, cm, mm
This field is the inside diameter of the tubes through which water is circulated for the system. The inside diameter is used to determine the convective heat transfer from the water to the inside surface of the hydronic tubing.
 
Length
Default: Autosize
Typical Range: N/A
Min Max: > 0
Units: ft, in/m, cm, mm
This field is the total length of pipe embedded in the surface. The length of the tube is used to determine the effectiveness of heat transfer from the fluid being circulated through the tubes and the tube/surface. Longer tubing lengths result in more heat being transferred to/from the radiant surface to the circulating fluid. This field is auto sizable.
back to Low Temperature Radiant top
 
Circuit
Circuit Length Method
Default: Autocalculate
Typical Range: N/A
Min Max: One per surface, Autocalculate
Units: N/A
This optional input allows the user to choose between modeling each surface in the radiant system as a single hydronic circuit or to allow the program to divide the surface into multiple parallel hydronic circuits based on the input field Circuit Length. To model as a single circuit choose One Per Surface. To model as multiple circuits choose Autocalculate which is the default option.
 
Circuit Length
Default: 350 ft/106.7 m
Typical Range: N/A
Min Max: 0
Units: ft, in/m, cm, mm
This field represents the length of each parallel hydronic circuit in a surface. It is only available when the circuit length method is set to Auto calculate.
back to Low Temperature Radiant top