System Types¶

Understanding the different HVAC system types supported by HHW Brick Application.

Overview¶

HHW Brick Application supports five main system types for heating hot water systems. Each system type has different equipment configurations and Brick class mappings.

Supported System Types¶

System Type	Description	Common Use	Equipment Created
Boiler	Generic boiler system	Legacy/generic buildings	Boiler, pumps
Non-condensing	Non-condensing boiler with heat exchanger	Older buildings	Boiler, HX, primary/secondary loops
Condensing	High-efficiency condensing boiler	Modern buildings	Condensing boiler, HX, loops
District HW	District hot water connection	Campus settings	District connection, HX, building loop
District Steam	District steam connection	Dense urban areas	Steam connection, HX, building loop

System Type Details¶

1. Boiler Systems¶

Generic boiler system without specific efficiency classification.

Equipment Hierarchy¶

graph TD
    B[Boiler] -->|has point| SP[Supply Temp]
    B -->|has point| RP[Return Temp]
    B -->|has point| F[Flow]
    B -->|feeds| P[Pump]

    style B fill:#ff9800
    style P fill:#2196f3

Created Equipment¶

Boiler (brick:Boiler)
Supply temperature sensor
Return temperature sensor
Flow sensor (if available)
Pumps (brick:Water_Pump)
Primary pumps
Variable frequency drives (if available)

CSV Example¶

# metadata.csv
tag,system,org
105,Boiler,Organization A

# vars_available_by_building.csv
tag,hw_supply_temp,hw_return_temp,hw_flow
105,1,1,1

2. Non-condensing Systems¶

Non-condensing boiler with heat exchanger separating primary and secondary loops.

Equipment Hierarchy¶

graph LR
    B[Boiler<br/>Primary] -->|feeds| HX[Heat<br/>Exchanger]
    HX -->|feeds| SL[Secondary<br/>Loop]
    B -->|has| PP[Primary<br/>Pump]
    SL -->|has| SP[Secondary<br/>Pump]

    style B fill:#ff9800
    style HX fill:#2196f3
    style SL fill:#4caf50

Created Equipment¶

Primary Side: - Boiler (brick:Boiler) - HW supply temperature - HW return temperature
- Flow rate - Firing rate (if available)

Primary Pumps (brick:Water_Pump)
Pump power
Pump speed
VFD status

Heat Transfer: - Heat Exchanger (brick:Heat_Exchanger) - Primary/secondary interface

Secondary Side: - Secondary Loop Equipment - Supply/return temperatures - Flow rate - Pumps with VFDs

CSV Example¶

# metadata.csv
tag,system,org,b_number
105,Non-condensing,Org A,2

# vars_available_by_building.csv
tag,hw_supply_temp,hw_return_temp,hw_flow,secondary_supply_temp,secondary_return_temp,secondary_flow,sup1,ret1,sup2,ret2
105,1,1,1,1,1,1,1,1,1,1

Multiple Boilers¶

The system can model multiple boilers:

# Building with 3 boilers
# metadata.csv: b_number=3
# Creates: Boiler_Primary_1, Boiler_Primary_2, Boiler_Primary_3

3. Condensing Systems¶

High-efficiency condensing boiler systems with same topology as non-condensing.

Key Differences¶

Feature	Non-condensing	Condensing
Boiler Type	`brick:Boiler`	`brick:Condensing_Boiler`
Efficiency	~80-85%	~90-98%
Exhaust Temp	High (>140°C)	Low (<60°C)
Return Temp	>60°C	Can be <60°C

Equipment Hierarchy¶

Same as non-condensing, but uses brick:Condensing_Boiler class.

CSV Example¶

# metadata.csv
tag,system,org
106,Condensing,Org A

# vars_available_by_building.csv (same format as non-condensing)
tag,hw_supply_temp,hw_return_temp,hw_flow
106,1,1,1

4. District Hot Water (District HW)¶

Building connected to a campus-wide hot water distribution system.

Equipment Hierarchy¶

graph LR
    DS[District<br/>Supply] -->|feeds| HX[Heat<br/>Exchanger]
    HX -->|feeds| BL[Building<br/>Loop]
    DS -->|has| DM[District<br/>Meter]
    BL -->|has| BP[Building<br/>Pump]

    style DS fill:#9c27b0
    style HX fill:#2196f3
    style BL fill:#4caf50

Created Equipment¶

District Side: - District Connection (brick:District_Hot_Water_System) - Supply temperature - Return temperature - Flow meter - Energy meter

Building Side: - Heat Exchanger (brick:Heat_Exchanger) - Building Loop - Secondary supply/return temperatures - Building circulation pumps - Control valves

CSV Example¶

# metadata.csv
tag,system,org
108,District HW,Org B

# vars_available_by_building.csv
tag,hw_supply_temp,hw_return_temp,hw_flow,secondary_supply_temp,secondary_return_temp
108,1,1,1,1,1

No Boilers¶

District systems do not create boiler entities, even if boiler-related data exists:

# If b_number > 0 in District HW system:
# ⚠ Warning logged: "District system but found boiler data"
# ✓ No boilers created (correct behavior)

5. District Steam¶

Building connected to campus steam distribution.

Equipment Hierarchy¶

graph LR
    DST[District<br/>Steam] -->|feeds| SC[Steam<br/>Condenser/HX]
    SC -->|feeds| BL[Building<br/>HW Loop]
    SC -->|returns| CR[Condensate<br/>Return]

    style DST fill:#9c27b0
    style SC fill:#ff5722
    style BL fill:#4caf50

Created Equipment¶

Steam Side: - District Steam Connection (brick:District_Steam_System) - Steam pressure - Steam temperature - Condensate return temperature

Conversion: - Steam-to-Water Heat Exchanger - Steam condensing - Hot water generation

Building Side: - Hot Water Loop - Supply/return temperatures - Pumps and controls

CSV Example¶

# metadata.csv
tag,system,org
109,District Steam,Org B

# vars_available_by_building.csv
tag,steam_pressure,condensate_temp,hw_supply_temp,hw_return_temp
109,1,1,1,1

System Type Selection¶

Auto-Detection¶

If you don't specify system_type, it's auto-detected from metadata:

converter = CSVToBrickConverter()
result = converter.convert_to_brick(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    building_tag="105"
    # system_type not specified - auto-detected
)

Manual Specification¶

You can override the metadata:

result = converter.convert_to_brick(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    building_tag="105",
    system_type="Condensing"  # Force this type
)

Filtering¶

Convert only specific system types:

# Convert only condensing systems
result = converter.convert_to_brick(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    system_type="Condensing"  # Filter
)

Equipment Numbering¶

Boiler Numbering¶

Boilers are numbered based on b_number in metadata and sensor patterns:

# metadata.csv: b_number=3
# Creates:
#   Boiler_Primary_1
#   Boiler_Primary_2
#   Boiler_Primary_3

Sensor-Based Detection¶

If b_number is missing, the converter infers from sensors:

# vars_available_by_building.csv
tag,sup1,ret1,fire1,sup2,ret2,fire2,sup3,ret3,fire3
105,1,1,1,1,1,1,1,1,1
# Detects 3 boilers from sup1-3, ret1-3, fire1-3

Pump Numbering¶

Similar logic for pumps:

# vars_available_by_building.csv
tag,pmp1_pwr,pmp1_spd,pmp2_pwr,pmp2_spd
105,1,1,1,1
# Detects 2 pumps

Point Mappings by System¶

Common Points (All Systems)¶

CSV Column	Brick Class
`hw_supply_temp`	`Hot_Water_Supply_Temperature_Sensor`
`hw_return_temp`	`Hot_Water_Return_Temperature_Sensor`
`hw_flow`	`Water_Flow_Sensor`
`outdoor_temp`	`Outside_Air_Temperature_Sensor`

Boiler-Specific Points¶

CSV Column	Brick Class	Systems
`fire1`, `fire2`, ...	`Firing_Rate_Sensor`	Boiler, Non-condensing, Condensing
`sup1`, `sup2`, ...	`Hot_Water_Supply_Temperature_Sensor`	Boiler, Non-condensing, Condensing
`ret1`, `ret2`, ...	`Hot_Water_Return_Temperature_Sensor`	Boiler, Non-condensing, Condensing

Secondary Loop Points¶

CSV Column	Brick Class	Systems
`secondary_supply_temp`	`Hot_Water_Supply_Temperature_Sensor`	Non-condensing, Condensing, District
`secondary_return_temp`	`Hot_Water_Return_Temperature_Sensor`	Non-condensing, Condensing, District
`secondary_flow`	`Water_Flow_Sensor`	Non-condensing, Condensing, District

District-Specific Points¶

CSV Column	Brick Class	Systems
`steam_pressure`	`Steam_Pressure_Sensor`	District Steam
`condensate_temp`	`Condensate_Temperature_Sensor`	District Steam

Validation and Warnings¶

System Type Mismatch¶

# Building marked as "District HW" but has boiler data
# ⚠ Warning: "District system but found boiler data"
# ✓ Boilers not created (correct)

Missing Equipment Count¶

# Boiler system but b_number=0
# ⚠ Warning: "Boiler system but b_number=0"
# ✓ Falls back to sensor detection

Inconsistent Data¶

# b_number=2 but sensors show 3 boilers
# ⚠ Warning: "b_number=2 but sensors show 3, using max"
# ✓ Creates 3 boilers

Choosing the Right System Type¶

When to Use Each Type¶

Boiler: - Generic/legacy systems - Simple heating setups - When specific efficiency unknown

Non-condensing: - Older buildings (pre-2000) - Systems with return temp >60°C - Standard efficiency boilers

Condensing: - Modern buildings (post-2000) - High-efficiency systems - Return temp can be <60°C

District HW: - Campus settings - Centralized hot water - No on-site boilers

District Steam: - Dense urban areas - Legacy campus systems - Steam-to-hot-water conversion

Examples by System Type¶

Convert All Non-condensing¶

from hhw_brick import BatchConverter

batch = BatchConverter()
results = batch.convert_all_buildings(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    output_dir="non_condensing_models/",
    system_type="Non-condensing"
)

Convert District Systems¶

# District HW
results_hw = batch.convert_all_buildings(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    output_dir="district_hw/",
    system_type="District HW"
)

# District Steam
results_steam = batch.convert_all_buildings(
    metadata_csv="metadata.csv",
    vars_csv="vars.csv",
    output_dir="district_steam/",
    system_type="District Steam"
)

Separate by Type¶

system_types = [
    "Non-condensing",
    "Condensing",
    "District HW"
]

for system in system_types:
    results = batch.convert_all_buildings(
        metadata_csv="metadata.csv",
        vars_csv="vars.csv",
        output_dir=f"models/{system.lower().replace(' ', '_')}/",
        system_type=system,
        show_progress=True
    )

    print(f"{system}: {results['successful']} buildings")

Next Steps¶

Sensor Mapping - Customize sensor mappings
Validation - Validate system models
Examples - Working examples

Continue to: Sensor Mapping →