Point Dictionary: CHW

Chilled-water plant point dictionary. Owning equipment: brick:Chiller / brick:Chilled_Water_Loop (both verified in Brick 1.4.4). On multi-chiller plants, machine rules require a coherent per-chiller identity; loop-common temperature/setpoint points are valid only where the card explicitly permits them. ASHRAE 223 local names were checked against 223p-1.0.0-ppr2.1.ttl (owl:versionInfo 1.0.0-ppr.2.1; SHA-256 1f156f9938c0be430d2216e01e31bb183c438ba318d8d4a23d2f074ebcd6f573), replacing the former unverified v1.0.0-2026 label. Water-ChilledWater identifies the chilled-water circuit, Fluid-Water intentionally leaves condenser-water composition generic, and Constituent-Refrigerant identifies the refrigerant behind host-derived saturation properties. The reference expresses chiller output in tons; 1 ton = 3.517 kW thermal and conversion belongs at binding, not in the graph.

chiller_kw

Chiller electrical input power

• 223P: QuantifiableObservableProperty on the Chiller via hasProperty
• QUDT unit: KiloW

brick:Active_Power_Sensor grep-verified (same mapping as hp elec_power), isPointOf brick:Chiller (verified). Consumed by CHW-0001’s kW/ton numerator.

chiller_tons

Chiller cooling output (thermal)

• 223P: QuantifiableObservableProperty on the Chiller via hasProperty
• QUDT unit: TON_FG

brick:Thermal_Power_Sensor grep-verified, but marked provisional for the unit: the reference (and the kW/ton convention) uses refrigeration tons while most BAS trend kW thermal or derive tons from flow x deltaT. Binding must land on tons (1 ton = 3.517 kW) or CHW-0001’s kW/ton and its baseline coefficients are silently wrong together. Often a host-derived point (flow x deltaT x cp).

chiller_cmd

Final individual-chiller run command (true = this machine is requested to operate)

• 223P: EnumeratedActuatableProperty on the Chiller via hasProperty

brick:Start_Stop_Command is exact and equipment-agnostic in Brick 1.4.4; attach it via isPointOf to this brick:Chiller. Bind the final stage command downstream of plant enable, lead/lag selection, and ordinary anti-recycle/interlock logic. A plant enable, cooling demand, availability, or fleet request is invalid for CHW-0008. ASHRAE 223 uses a Binary-OnOff EnumeratedActuatableProperty on s223:Chiller.

chiller_status

Independent individual-chiller run proof (true = this machine is actually operating)

• 223P: EnumeratedObservableProperty on the Chiller via hasProperty

brick:Run_Status is exact in Brick 1.4.4; attach it to this brick:Chiller. Bind proof of capacity-producing operation or compressor run, not availability, enable-ready, alarm-free, an echoed command, or a fleet OR. Define the rule-instance boundary explicitly for modular or multi-circuit equipment. ASHRAE 223 uses a Binary-OnOff EnumeratedObservableProperty on s223:Chiller.

cwst

Condenser water supply (chiller-leaving) temperature

• 223P: QuantifiableObservableProperty on the condenser water leaving connection point
• QUDT unit: DEG_C

brick:Leaving_Condenser_Water_Temperature_Sensor is exact in Brick 1.4.4. ASHRAE 223 uses Fluid-Water on the connection point; leaving direction is topology in the pattern, not a nonexistent aspect local name. Baseline regressor input for CHW-0001 (condenser lift proxy). LOOP-SIDE WARNING: this is the WARM side (chiller-leaving, chiller-to-tower). A future cooling-tower approach rule needs the COLD side (tower-leaving, tower-to-chiller = entering condenser water) — a different point; do not wire a tower rule here by name alone (internal deep-read finding, 2026-08-18).

chwst

Chilled water supply (chiller-leaving) temperature

• 223P: QuantifiableObservableProperty on the CHW leaving connection point
• QUDT unit: DEG_C

brick:Leaving_Chilled_Water_Temperature_Sensor is exact in Brick 1.4.4. ASHRAE 223 uses Water-ChilledWater on the connection point; leaving direction is expressed by topology rather than an aspect. For CHW-0007 prefer the individual chiller evaporator/barrel outlet. A common mixed-header value is acceptable only when the active staged machine(s) genuinely control that same header target; it is not a per-machine proxy by name alone. CHW-0001 may use the fitted model’s documented machine/plant boundary; CHW-0004 intentionally uses loop supply.

chwrt

Chilled water return (chiller-entering) temperature

• 223P: QuantifiableObservableProperty on the CHW entering connection point
• QUDT unit: DEG_C

brick:Entering_Chilled_Water_Temperature_Sensor is exact in Brick 1.4.4 — ‘return’ at the plant is ‘entering’ at the chiller. ASHRAE 223 uses Water-ChilledWater on the connection point; entering direction is expressed by topology rather than an aspect. Brick 1.4.4 also carries Chilled_Water_Return_Temperature_Sensor, but the entering-form matches the chiller-owned binding these rules assume. Consumed by CHW-0004.

chiller_load

Chiller load (percent of capacity, from the chiller controller)

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

Brick 1.4.4 has no chiller-percent-load class, so the Brick mapping is null and the 223 pattern is provisional. Typical per-machine sources are the chiller controller’s PLR/RLA% or host-derived tons/design_tons. CHW-0001 and CHW-0007 require the same individual machine as their other inputs. CHW-0004 deliberately uses a plant-loaded proxy; CHW-0002 may use an explicitly documented plant range. A fleet maximum is not per-machine load.

chwst_sp

Chilled water supply temperature setpoint

• 223P: QuantifiableActuatableProperty on the CHW loop via hasProperty
• QUDT unit: DEG_C

brick:Leaving_Chilled_Water_Temperature_Setpoint is exact in Brick 1.4.4. ASHRAE 223 uses Water-ChilledWater plus the exact Aspect-Setpoint; leaving direction belongs to connection topology. CHW-0002 watches the loop setpoint range. CHW-0007 requires the final active target controlling its bound chwst: prefer the individual chiller’s delivered target, or use a common header setpoint only when the staged machines truly control that same mixed-header point. A supervisory request upstream of local reset, demand, or safety limits is not the active target.

dp_sp

CHW loop differential pressure setpoint

• 223P: QuantifiableActuatableProperty on the CHW loop via hasProperty
• QUDT unit: KiloPA

brick:Chilled_Water_Differential_Pressure_Setpoint is exact in Brick 1.4.4. ASHRAE 223 uses Water-ChilledWater with exact Aspect-Delta and Aspect-Setpoint terms. CHW-0003 watches this point’s range (AHU-0024 dsp_sp precedent).

chw_valve_max

Maximum CHW coil valve position across served coils (host-derived)

• 223P: Host Function hasOutput QuantifiableProperty; no single physical point
• QUDT unit: PERCENT

HOST-DERIVED (zone_reheat_fraction / satisfied_zone_fraction precedent): the reference’s chw_valve_positions is a vector across AHU/FCU cooling coils; the rule needs only its max, so the host binds max() over the coil valve commands it serves. ASHRAE 223 PPR2.1 provides Function/hasOutput/QuantifiableProperty and Aspect-Maximum; the exact cross-equipment aggregation pattern remains provisional. CHW-0003’s ‘no coil starving’ conjunct. Engine vector blocks could compute this in-graph once the points contract grows vector bindings (tracked in internal engine-block-inventory research notes).

cond_sat_temp

Condensing saturation temperature (HOST-DERIVED: discharge/liquid pressure via refrigerant P-T lookup)

• 223P: Host Function hasOutput QuantifiableProperty derived from refrigerant pressure and a refrigerant-specific P-T relation
• QUDT unit: DEG_C

Host-derived P-T saturation lookup from measured discharge/liquid pressure (hp dict precedent, duplicated per the lint’s own-family resolution rule). ASHRAE 223 PPR2.1 provides Function/hasOutput/QuantifiableProperty and Constituent-Refrigerant, but no exact condensing or derived aspect; that semantic detail remains in the derivation record. Consumed by CHW-0005 condenser-approach-high: approach = cond_sat_temp − cwst. Refrigerant-specific lookup is the host’s, documented per binding.

evap_sat_temp

Evaporating saturation temperature (HOST-DERIVED: suction pressure via refrigerant P-T lookup, or coil-surface proxy)

• 223P: Host Function hasOutput QuantifiableProperty derived from refrigerant pressure and a refrigerant-specific P-T relation
• QUDT unit: DEG_C

Mirror of the hp dict entry (duplicated per the lint’s own-family resolution rule; same refrigerant P-T host obligation — the lookup is refrigerant-specific and lives at the host). ASHRAE 223 PPR2.1 provides Function/hasOutput/QuantifiableProperty and Constituent-Refrigerant, but no exact evaporating or derived aspect; that semantic detail remains in the derivation record. CHW-0006 evaporator approach = chwst − evap_sat_temp; healthy approach is small and positive, and tube fouling or low charge widens it.