Point Dictionary: HW

Hot-water and boiler-plant point dictionary. Owning equipment is brick:Boiler (brick:Natural_Gas_Boiler for the gas-fired subclass); multi-boiler machine rules bind one coherent boiler and plant rules define their configured fleet and header explicitly. ASHRAE 223 mappings were checked against 223p-1.0.0-ppr2.1.ttl (owl:versionInfo 1.0.0-ppr.2.1; SHA-256 1f156f9938c0be430d2216e01e31bb183c438ba318d8d4a23d2f074ebcd6f573), not an inferred final 2026 release. That artifact imports QUDT 3.1.8; the quantity-kind and unit local names here were independently checked against the repository-declared QUDT 3.1.4 artifacts. The legacy reference covers HW-0001..0003; later loop and regulation rules are library-authored expansions.

boiler_status

Boiler firing status (true = firing)

• 223P: EnumeratedObservableProperty on the Boiler via hasProperty

brick:Run_Status grep-verified, isPointOf brick:Boiler (verified). Reference Haystack markers: boiler, run. ‘Firing’ vs ‘enabled’ matters for HW-0001’s start counting: bind the FIRING/flame status where available — an enable status hides burner cycling and undercounts starts (comp_status OR-undercount precedent). Consumed by HW-0001 (edge counting) and HW-0003 (lockout).

thermal_power

Boiler useful thermal output (host-derived from aligned flow and water temperatures)

• 223P: Host Function hasOutput a QuantifiableProperty for useful boiler HeatFlowRate
• QUDT unit: KiloW

HOST-DERIVED for this canonical contract: aligned HW flow x leaving/entering delta-T x density x specific heat, with sign and unit conventions recorded. PPR2.1 provides Function/hasOutput/QuantifiableProperty but no exact derived-useful-heat aspect. A physical BTU meter is an alternative source, but its observable sensor model is distinct from this calculation. HW-0002 efficiency numerator.

fuel_power

Boiler fuel input power (fuel flow x heating value)

• 223P: Host Function hasOutput a QuantifiableProperty for fuel input Power derived from fuel flow and heating value
• QUDT unit: KiloW

HOST-DERIVED from fuel flow x HHV or LHV; pick one declared convention and keep it consistent with the fitted baseline. Brick 1.4.4 has gas usage/flow sensors but no exact fuel-input-power point. Fluid-NaturalGas is the verified PPR2.1 medium. HW-0002 efficiency denominator and divide guard.

boiler_firing_rate

Boiler firing rate (percent of maximum fire)

• 223P: QuantifiableObservableProperty on the Boiler via hasProperty
• QUDT unit: PERCENT

No exact Brick 1.4.4 percent-firing-rate class. Bind actual normalized burner modulation feedback when available; a command is a disclosed proxy, not the same observable property. A plant aggregate must be capacity-weighted (total applicable input divided by total applicable rated input), never a simple average across unequal boilers. Consumed by HW-0002 and HW-0011.

hw_pump_status

HW pump run status (true = running)

• 223P: EnumeratedObservableProperty on the Pump via hasProperty

brick:Pump_On_Off_Status grep-verified (carried from pmp pump_status). Second branch of HW-0003’s lockout OR — pumps circulating above lockout waste energy even with the boiler off.

oat

Outdoor air temperature

• 223P: TemperatureSensor observes a QuantifiableObservableProperty in an OutdoorPhysicalSpace representative of the plant
• QUDT unit: DEG_C

Carried from the ahu/erv dictionaries (brick:Outside_Air_Temperature_Sensor, grep-verified there). HW-0003’s lockout comparator; its diagnosis list includes an OAT sensor reading low — pair with sensor-health rules when phase 3 opens.

hws_temp

Hot water supply temperature (loop supply / boiler leaving)

• 223P: TemperatureSensor observes a QuantifiableObservableProperty at the hot-water plant or boiler outlet ConnectionPoint
• QUDT unit: DEG_C

brick:Leaving_Hot_Water_Temperature_Sensor is the active Brick 1.4.4 class; the former supply form is deprecated. PPR2.1 expresses leaving/supply direction through outlet topology, not a free-text aspect. Bind the same controlled header or boiler outlet required by the consuming card.

hwr_temp

Hot water return temperature

• 223P: TemperatureSensor observes a QuantifiableObservableProperty at the hot-water plant or boiler inlet ConnectionPoint
• QUDT unit: DEG_C

brick:Entering_Hot_Water_Temperature_Sensor is the active Brick 1.4.4 class; the former return form is deprecated. PPR2.1 expresses entering/return direction through inlet topology. HW-0004 delta-T subtrahend.

hws_temp_sp

Hot water supply temperature setpoint

• 223P: QuantifiableActuatableProperty with Aspect-Setpoint controlling the hot-water plant or boiler outlet ConnectionPoint
• QUDT unit: DEG_C

brick:Leaving_Hot_Water_Temperature_Setpoint is exact in Brick 1.4.4. PPR2.1 uses Water-HotWater plus Aspect-Setpoint; outlet direction is topology. Bind the final active target controlling the same hws_temp location, not an upstream reset request.

hw_dp

HW loop differential pressure

• 223P: QuantifiableObservableProperty for hot-water loop pressure with Aspect-Delta
• QUDT unit: KiloPA

brick:Hot_Water_Differential_Pressure_Sensor grep-verified. Context point for the DP rules; HW-0005’s primary evidence is pump speed, not DP itself.

hw_dp_sp

HW loop differential pressure setpoint

• 223P: QuantifiableActuatableProperty for hot-water loop pressure with Aspect-Delta and Aspect-Setpoint
• QUDT unit: KiloPA

brick:Hot_Water_Differential_Pressure_Setpoint grep-verified. HW-0006 watches this point’s RANGE (AHU-0024/CHW-0003 idiom).

hw_pump_vfd_speed

HW pump VFD speed feedback (0-100%)

• 223P: QuantifiableObservableProperty on the equipment via hasProperty
• QUDT unit: PERCENT

PPR2.1 supports an observable DimensionlessRatio/PERCENT property on the pump motor or VFD. Brick 1.4.4 has Motor_Speed_Sensor, but its inherited physical Speed unit list does not include PERCENT, so the normalized-percent mapping is provisional. Bind actual feedback where possible; command or EnergyPlus flow fraction is a documented proxy.

boiler_cmd

Boiler enable command (true = commanded to fire)

• 223P: EnumeratedActuatableProperty on the Boiler via hasProperty

brick:Start_Stop_Command attached via isPointOf to brick:Boiler (pump_cmd precedent). The command HALF of the boiler_status pair; HW-0009 proof-of-operation compares the two. Bind the plant-level enable the BAS actually writes — a lead/lag sequencer’s internal stage command is upstream of what this point means.

boiler_stage_count

Number of staging units in the configured boiler fleet currently proven firing

• 223P: Host aggregation represented as a Function whose hasOutput is a QuantifiableProperty for Count in NUM
• QUDT unit: NUM

HOST-DERIVED sum of valid per-unit firing statuses, not enable or availability states. Record fleet membership, status freshness, aggregation timestamp, and whether a staging unit is a whole boiler or modular burner section. Do not mix unlike stage units in one scalar count.

hw_plant_load_fraction

Current useful hot-water plant heating load divided by the commissioned capacity of the configured eligible staging fleet

• 223P: Host calculation represented as a Function whose hasOutput is a QuantifiableProperty for DimensionlessRatio in UNITLESS
• QUDT unit: UNITLESS

HOST-DERIVED 0..1 ratio. Record the thermal-load derivation, numerator averaging, capacity source/version, eligible-fleet membership, and denominator-change policy. The capacity basis must remain stable through one evaluation window; if membership or denominator changes, restart evaluation or report NO_EVAL.