Multi-zone with hydronic heating

The previous tutorials provided idealized examples. In this tutorial, we will simulate a three-zone building with a hydronic heating system, aiming for a more realistic model. Below, we will describe the configuration file, highlighting key points:

Default Construction Values: Trano includes a set of predefined construction, glazing, and gas properties. To use these in your configuration file, add the following line:
```
default: !include_default
```
Emission Systems: Each space is assigned a list of emission systems. These are linked to a radiator object (RADIATOR:001) and a valve object (VALVE:001), with the valve being used for control instead of the radiator:
```
emissions:
  - radiator:
      id: RADIATOR:001
  - valve:
      id: VALVE:001
      control:
        emission_control:
```
Hydronic System Definition: A complete hydronic system must be defined, including the boiler, pump, and
```
                                                   
```
various valves. Default parameters will be utilized if not specified: href="#__codelineno-2-1">systems: - boiler: id: BOILER:001 control: boiler_control: - pump: id: PUMP:001 control: collector_control: outlets: - THREE_WAY_VALVE:001 - THREE_WAY_VALVE:002 inlets: - BOILER:001 - split_valve: id: SPLIT_VALVE:001 inlets: - VALVE:003 - VALVE:001 outlets: - BOILER:001 - three_way_valve: id: THREE_WAY_VALVE:001 control: three_way_valve_control: outlets: - TEMPERATURE_SENSOR:001 - SPLIT_VALVE:001 - temperature_sensor: id: TEMPERATURE_SENSOR:001 outlets: - RADIATOR:001 - RADIATOR:003 - split_valve: id: SPLIT_VALVE:002 inlets: - VALVE:002 outlets: - BOILER:001 - three_way_valve: id: THREE_WAY_VALVE:002 control: three_way_valve_control: outlets: - TEMPERATURE_SENSOR:002 - SPLIT_VALVE:002 - temperature_sensor: id: TEMPERATURE_SENSOR:002 inlets: - THREE_WAY_VALVE:002 outlets: - RADIATOR:002

Why the layout of this tutorial is wrong

The pump of this tutorial is before the three-way valves

This tutorial wires the hydronic system as boiler -> pump -> three-way valves -> sensors -> radiators. That layout does not work as a supply temperature control, and Trano reports it with a HydronicLayoutWarning ("WRONG HYDRONIC LAYOUT") on each three-way valve. It is kept as it is so that existing models keep working; build new models as in Hydronic heating with mixing circuits.

What the three-way valves are meant to do. Each valve has a controller that measures the water after the valve (TEMPERATURE_SENSOR) and should hold it at a set point, 90 degC by default, by mixing the hot water of the boiler with the cooler return water of the radiators.

What they do here. The pump pushes the water into port_1 of the valves. The water inside a valve is then at a higher pressure than the return, so port_3 sends water back to the boiler instead of drawing return water in. Closing the valve diverts hot water to the return; the water that still reaches the radiators is as hot as the boiler supply. The valve can reduce the flow to the radiators, never lower their temperature.

What goes wrong. The boiler charges its storage tank until the bottom of the tank is 5 K above tsup_nominal, so the top of the tank, which feeds the radiators, ends about 15 K above it: about 95 degC with the default 80 degC. Above the 90 degC set point, the controller closes the valve to cool the water; that does not cool it, so it keeps closing until the valve is shut. Almost no water reaches the radiators, the sensor sits in still hot water and keeps reading "too hot", and the valve never reopens. In simulation, the rooms of tests/models/three_zones_hydronic.yaml averaged 16 degC instead of 21 degC. This tutorial avoids it only because its boiler is set to 70 degC (tsup_nominal: 343.15): the tank stays below 90 degC, the valves stay fully open and in fact control nothing.

The workaround Trano applies. When the supply of a storage boiler can exceed the set point of such a valve, Trano raises the set point of the valve 5 K above the expected top of the tank (100 degC for the default 80 degC boiler) and says so in the warning ("WORKAROUND APPLIED"). The valve then stays open and the rooms are heated again (21 degC in simulation), but the radiators receive the boiler water unmixed: nothing limits their supply temperature, the radiator valves alone control the rooms. To make it an error instead, filter the warning: warnings.simplefilter("error", HydronicLayoutWarning) (from trano.validation.issues).

The fix. Put one pump after each three-way valve and its sensor, and list the return split valve in the inlets of the valve: the pump then draws the return water into the valve, which mixes and holds its set point (supply_temperature_setpoint of three_way_valve_control) whatever the boiler supply. See Hydronic heating with mixing circuits.

Input configuration file

The described configuration represents a multi-room building designed for occupancy, featuring a combination of thermal insulation materials with consistent thermal properties. It includes three distinct spaces (rooms) with varying floor areas and heating systems. Each space has specific external wall construction types and window placements to optimize energy efficiency and natural light. The building also has a centralized heating system with a boiler, radiators, and temperature control elements to manage indoor climate effectively. Overall, it appears to be a residential or small commercial building with an emphasis on energy efficiency and heating performance.

default: !include_default
material:
  - id: MATERIAL:001  # facing brick
    thermal_conductivity: 0.6
    density: 1800.0
    specific_heat_capacity: 840.0
  - id: MATERIAL:002  # mineral wool
    thermal_conductivity: 0.035
    density: 30.0
    specific_heat_capacity: 1030.0
  - id: MATERIAL:003  # gypsum plaster
    thermal_conductivity: 0.5
    density: 1300.0
    specific_heat_capacity: 1000.0

constructions:
  - id: CONSTRUCTION:001
    layers:
      - material: MATERIAL:001
        thickness: 0.1
      - material: MATERIAL:002
        thickness: 0.1
      - material: MATERIAL:003
        thickness: 0.015
spaces:
  - occupancy:
    parameters:
      floor_area: 49.0
      average_room_height: 2.5
    id: SPACE:001
    external_boundaries:
      external_walls:
        - surface: 20
          azimuth: 0
          tilt: wall
          construction: CAVITYWALL:001
        - surface: 30
          azimuth: 1.57
          tilt: wall
          construction: CAVITYWALL:001
        - surface: 50
          azimuth: 3.14
          tilt: wall
          construction: CAVITYWALL:001
      windows:
        - surface: 5.0
          construction: EPCDOUBLE:001
          azimuth: 0
          tilt: wall
        - surface: 2.0
          construction: EPCDOUBLE:001
          azimuth: 3.14
          tilt: wall
      floor_on_grounds:
        - surface: 49
          construction: CONCRETESLAB:001
    emissions:
      - radiator:
          parameters:
            nominal_heating_power_positive_for_heating: 5000
            dp_nominal: 100
          id: RADIATOR:003
      - valve:
          id: VALVE:003
          control:
            emission_control:
  - occupancy:
      parameters:
        gain: "[ 45; 90; 40 ]"
        occupancy: 3600*{16, 21}
    parameters:
      floor_area: 40
      average_room_height: 2.5
    id: SPACE:002
    external_boundaries:
      external_walls:
        - surface: 25
          azimuth: 0
          tilt: wall
          construction: CAVITYWALLPARTIALFILL:001
        - surface: 25
          azimuth: 1.57
          tilt: wall
          construction: CAVITYWALLPARTIALFILL:001
        - surface: 34
          azimuth: 3.14
          tilt: wall
          construction: CAVITYWALLPARTIALFILL:001
      windows:
        - surface: 5.0
          construction: INS2AR2020:001
          azimuth: 0
          tilt: wall
        - surface: 2.0
          construction: INS2AR2020:001
          azimuth: 3.14
          tilt: wall
      floor_on_grounds:
        - surface: 40
          construction: CONCRETESLAB:001
    emissions:
      - radiator:
          parameters:
            nominal_heating_power_positive_for_heating: 4000
          id: RADIATOR:001
      - valve:
          id: VALVE:001
          control:
            emission_control:
  - occupancy:
      parameters:
        gain: "[35; 70; 30]"
        occupancy: 3600*{10, 14}
    parameters:
      floor_area: 50.0
      average_room_height: 2.5
    id: SPACE:003
    external_boundaries:
      external_walls:
        - surface: 22
          azimuth: 3.14
          tilt: wall
          construction: CONSTRUCTION:001
        - surface: 17
          azimuth: 3.14
          tilt: wall
          construction: CONSTRUCTION:001
        - surface: 36
          azimuth: 3.14
          tilt: wall
          construction: CONSTRUCTION:001
      floor_on_grounds:
        - surface: 50.0
          construction: CONCRETESLAB:001
    emissions:
      - radiator:
          parameters:
            nominal_heating_power_positive_for_heating: 4000
          id: RADIATOR:002
      - valve:
          id: VALVE:002
          control:
            emission_control:
internal_walls:
  - space_1: SPACE:001
    space_2: SPACE:002
    construction: CAVITYWALL:001
    surface: 20
  - space_1: SPACE:002
    space_2: SPACE:001
    construction: CONSTRUCTION:001
    surface: 15
  - space_1: SPACE:002
    space_2: SPACE:003
    construction: CAVITYWALLPARTIALFILL:001
    surface: 22
systems:
  - boiler:
      # 12 kW for a design heat loss of 9.5 kW at -8 degC
      parameters:
        nominal_heating_power: 12000
      id: BOILER:001
      control:
        boiler_control:
          id: BOILER_CONTROL:001
          # the tank is charged to 70-75 degC: below the 90 degC set point of the three-way valves, which
          # divert the water to the return and cannot cool the supply of the radiators
          parameters:
            tsup_nominal: 343.15
  - pump:
      id: PUMP:001
      control:
        collector_control:
      outlets:
        - THREE_WAY_VALVE:001
        - THREE_WAY_VALVE:002
      inlets:
        - BOILER:001
  - split_valve:
      id: SPLIT_VALVE:001
      inlets:
        - VALVE:003
        - VALVE:001
      outlets:
        - BOILER:001
  - three_way_valve:
      id: THREE_WAY_VALVE:001
      control:
        three_way_valve_control:
      outlets:
        - TEMPERATURE_SENSOR:001
        - SPLIT_VALVE:001
  - temperature_sensor:
      id: TEMPERATURE_SENSOR:001
      outlets:
        - RADIATOR:001
        - RADIATOR:003
  - split_valve:
      id: SPLIT_VALVE:002
      inlets:
        - VALVE:002
      outlets:
        - BOILER:001
  - three_way_valve:
      id: THREE_WAY_VALVE:002
      control:
        three_way_valve_control:
      outlets:
        - TEMPERATURE_SENSOR:002
        - SPLIT_VALVE:002
  - temperature_sensor:
      id: TEMPERATURE_SENSOR:002
      inlets:
        - THREE_WAY_VALVE:002
      outlets:
        - RADIATOR:002

The following code snippet demonstrates how to create the model using Trano with the IDEAS library.

Test tutorials

    from trano.main import create_model

    create_model(
        path_to_yaml_configuration_folder / "three_zones_hydronic_heating.yaml",
        library="IDEAS",
    )

General Explanation

The code snippet imports a function to create a model based on a YAML configuration file for a specific hydronic heating system. It uses a library named "IDEAS" for its functionalities.

Parameters Description

path_to_yaml_configuration_folder:
Path object pointing to the directory containing YAML configuration files.
"three_zones_hydronic_heating.yaml":
The specific YAML configuration file that defines the model parameters and settings for a three-zone hydronic heating system.
library:
A string that specifies the library to be used for model creation. In this case, it is set to "IDEAS".

Outputs

The figure below illustrates the building components of the generated model. In addition to the building envelope and emission sub-components, it also includes components for the hydronic distribution system and the production boiler.

hydronic_1

Opening the emission component reveals the various radiators and valves connected to different spaces, which together compose the emission system.

hydronic_2

The figure below illustrates the hydronic distribution system connecting the emission system to the boiler.

hydronic_3

Since the IDEAS library was utilized, the figure below illustrates the content of the envelope sub-component that incorporates the IDEAS sub-components.

hydronic_4

Results

Two January weeks simulated with IDEAS: the zone temperatures against their set point and the outdoor temperature, the heat the radiators give the rooms and the gas the boiler burns as it charges its storage tank in cycles (all on the data bus of the model). The rooms are heated to 21 degC from 7 to 19 h and fall back to 16 degC at night.