Designing heating systems with convective radiators

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Product InstalSystem 5
Type of article DESIGNING LESSON
Source for translation 2022-10-19

Scope of lesson

The article presents the method of designing a heating system with convector heaters from the source to terminal units, inclusive of complete control and balancing.

Modules and program configuration

  • InstalSystem 5 package containing the module:
    • Double-pipe heating systems with convector heaters
    • Heating systems


We encourage you to see the video from our webinars on the topics described in this article:

The webinars present the topics described in this article, but they aren’t a recording of this lesson.

Project file

The project file used in this lesson: Convective heating installation with radiators in residential building (example for the lesson).

Inital state

A design that includes the structure of the building (storeys, rooms). The values of design heat load of rooms are defined for heating.

Steps to perform

Loading catalogues and setting project default data

  1. Project scope tab - determine project scope: Heating systems.
  2. Storeys management tab – verify and append basic parameters:
    • Default distance between floor and pipe-runs for medium distribution to radiator system (ΔHpipe-run,).
    • Default distance between sill and floor (Hs).
    • Default width of recess - this value has an impact on the length of radiators located elsewhere than under windows (Recess width).
  3. Catalogues tab – load catalogues of products required for the project.
  4. Thermal systems/Sources tab – verify parameters:
    • Default supply temperature (θs,H).
  5. Thermal systems/Distribution system/Types and default data tab – append default types:
    • Default pipe types and insulation,
    • Default valve types,
    • Default types of fittings and manifolds,
    • Verify Hydraulic regulation options.
      1. Distribution system/Types and default data

  6. Thermal systems/Distribution system/Pipe and insulation sizing options tab – verify pipe and insulation sizing parameters.
  7. Thermal systems/Radiators/Radiators/Radiator valves - types and default data tab – append default types:
    • Default radiator type,
    • Default bathroom radiator type,
    • Default radiator connection system,
    • Default bathroom radiator connection system,
    • Valve on supply rad. circuit pipes,
    • Valve on return rad. circuit pipes,
    • Default right side conn. radiator type,
    • Default radiator connection system (right/left/middle conn.),
    • Default valves for down-feed radiators - note proper application: for double-pipe system,
    • Default radiator valve set - note proper application: for double-pipe system,
    • Catalogue for selecting valve heads or valve actuators,
    • Verify Common settings.

2. Radiators/Radiator valves - types and default data

  1. . Thermal systems/Radiators/Radiator sizing options tab – verify and append basic parameters:
    • Default restrictions of radiator size (Default sizing method),
    • Radiator sizing options,
    • Additions for radiator size.
      3. Radiator sizing options

Editing the system - convector radiators

Inserting convector radiators and graphic editing

Carry out inserting and graphic editing operations using the AUTO mode, Flip horizontally, Select multiple functions.

  1. Select editing scope Convectional.
  2. Insert multiple radiators under the windows/into recesses. This operation requires the structure of the building to be created beforehand, including windows/recesses.
    For more information, see: Preparation of building structure
  3. Insert radiators manually at other locations.

Change of radiator installation height/depth

  1. Adjust the:
  • installation height of bathroom radiators (Distance from floor (set in storey data));
  • installation depth of trench heaters (Distance from floor (set in storey data) - enter negative value equal to trench depth).

Inserting Radiator valves

  1. Place components: Radiator valves on selected radiators.

Editing Connection type

  1. Change Connection type of selected radiators using tools for marking multiple components.

Editing the system - append drawings with double-pipe medium distribution system


  1. Insert Source.

Arranging the system

  1. Arrange the system starting from Source in the separate parts of the building including all radiators without connecting them. Draw the system using the Pipe-run pair with adequate spacing between, using the AUTO and ORTO modes.

Connecting radiators to the system

  1. Connect the radiators to the distribution system using the Automatically connect terminal units function and tools for marking multiple components, and, if necessary, using the Pipe-run pair and the AUTO and ORTO modes.


  1. Insert Valve on feed and return branches of non-integrated radiators. Note whether valves on the branches adhere to radiators and the shape of valves (straight/angle). The shape of valves has an impact on proper selection of radiator connections.
  2. Adjust valve orientation where default orientation is incorrect.

Verification of the correctness of building structure

  1. Verify the correctness of system structure using the Check connections function (key shortcut: Shift + F2).
  2. Verify the correctness of system structure and find conflicts using 3D view.
    4. 3D view

For more information, see: Verification of the correctness of building structure

Editing system component data


  1. Adjust the contribution of the terminal unit in heat load coverage of the room by radiators, (Contribution [%]).
  2. Specify additions to radiator dimensions, other than default additions.
  3. Change radiator sizing method or default limitations of: Height, Length or Depth of the terminal unit - pay special attention to terminal units not installed in recesses (e.g. bathroom radiators).
  4. Change radiator type for radiators other than default. When necessary, select specific radiator from catalogue,
  5. Determine the Anchor - point in relation to which the Length of the radiator will change, while that point will not change its position in the plan view.


  1. Verify data of valves/fittings inserted on the radiators or in the system.

Editing the contribution in heat load coverage for the room

An editor is available for the room to declare the percentage contribution of each heat source to the heat demand. The output of sources other than the radiator or radiant heating system (e.g. fireplace, electric heater, etc.) is not calculated by the program, but the estimated contribution of these sources to the room heat demand can be taken into account.

In the editor, it is also possible to declare the method for calculating the required output for the room and to fill in the data required for the selected method.

5. Heat load coverage editor

Calculations and diagnostics

  1. Launch complete calculations by clicking the calculator icon Calculator.png in section Calculations of the toolbar.
  2. Verify calculation results paying special attention to:
    • heat demand coverage in rooms,
      5. List of rooms - heating

    • size of radiators,
      6. Heating terminal units

    • selection of radiator connections,
    • messages about unbalanced flow in circuits.

For more information, see: Calculations and diagnostics

Generation of schematic views

Schematic views should be created in accordance with: Automatically generate schematic views.

Preparing drawings for printing/exporting

Zaznaczyć/odznaczyć opcję Show the hooks on the radiators w Drawing options.
For more information, see: Preparation of drawings for export/printing