{
  "schema_version": "2.2",
  "concept": {
    "name": "Polar Bear two-section modular water source heat pump",
    "short_name": "Two-section modular concept",
    "status": "proposed_concept",
    "status_statement": "A proposed next-generation architecture. It is not an available, listed, rated or tested product, and no prototype exists. Legacy confirmed models remain the only products documented in the catalog. Loads, carry weights, envelope, materials, connection sizes and performance are unverified until physical prototypes and engineering checks exist.",
    "objective": "Design objective: deliver the heat pump to the home in two transport sections intended to be easier to bring through a home's doorways and stairways than one cabinet, then join them on site without opening the refrigerant circuit. No envelope or clearance has been defined yet, so fit through any particular opening is not demonstrated.",
    "prepared": "2026-09-23",
    "inspiration": [
      {
        "title": "Seresco NE Compact Series (product page)",
        "url": "https://serescodehumidifiers.com/products/ne-compact-series/",
        "principles": [
          "Service vestibule kept outside the process airstream so critical components can be serviced while the unit runs",
          "Multiple supply-air connection options and mirror configurations for duct flexibility",
          "Compact retrofit access and stacked (double-decker) versions to add capacity without extra floor space"
        ]
      },
      {
        "title": "Seresco NE Series brochure with optional R3 expansion module (PDF)",
        "url": "https://serescodehumidifiers.com/documents/brochures/Seresco-NE-Series-R3-Module.pdf",
        "principles": [
          "A section that mounts beneath the main unit and can ship separately",
          "Field-assembled sections for retrofit, with the mechanical vestibule protecting refrigeration controls"
        ]
      }
    ],
    "inspiration_boundary": "Architectural principles only. No Seresco geometry, branding, dimensions, weights, performance data or patented mechanisms are used, and a pool dehumidifier is not a water source heat pump."
  },
  "claim_tiers": {
    "source": "Source-supported: stated in Dennis Campbell's supplied documents for legacy Polar Bear equipment.",
    "principle": "General engineering principle: from a cited public technical source, not specific to Polar Bear.",
    "proposed": "Proposed concept: a design intent for the two-section platform that has not been built, tested or validated."
  },
  "legacy_basis": [
    {"id": "L1", "tier": "source", "text": "Electrical control cabinetry is located above the condensate pan and drains.", "source": "Dennis Campbell, design philosophy document, Cabinet section"},
    {"id": "L2", "tier": "source", "text": "Cabinets are satin-coat galvanized steel with baked powder coat; all water pipe openings have rubber grommets; cabinets carry 1-inch acoustic lining.", "source": "Dennis Campbell, design philosophy document, Cabinet section"},
    {"id": "L3", "tier": "source", "text": "The condensate pan is stainless steel.", "source": "Dennis Campbell, design philosophy document, Cabinet section"},
    {"id": "L4", "tier": "source", "text": "Standard relays are used instead of proprietary circuit boards; one generic anti-short-cycle and lock-out board is used and can be sourced from any refrigeration wholesaler.", "source": "Dennis Campbell, design philosophy document, Electrical Control Components"},
    {"id": "L5", "tier": "source", "text": "Closed-loop circulators are installed in the piping just outside the heat pump; hot-water circulators use bronze housings for the domestic circuit.", "source": "Dennis Campbell, design philosophy document, Circulator Pumps and Hot Water Circulator sections"},
    {"id": "L6", "tier": "source", "text": "The water coil can be ordered in copper for most closed loops or copper-nickel for open loops.", "source": "Dennis Campbell, design philosophy document, Water Coil section"},
    {"id": "L7", "tier": "source", "text": "A desuperheater is a small water coil that takes heat from the compressor discharge through a double-wall heat exchanger to preheat domestic hot water; S6 and S12 in legacy model names denote twin desuperheaters.", "source": "Dennis Campbell, design philosophy document and 16-page specification, page 1"},
    {"id": "L8", "tier": "source", "text": "K5, K10, K15 and K20 in legacy model names denote electric duct heaters of 5, 10, 15 and 20 kW.", "source": "Dennis Campbell, 16-page specification, pages 1 to 3"},
    {"id": "L9", "tier": "source", "text": "Legacy families include vertical water-to-air, horizontal split water-to-air with a separate air handler, water-to-water, water-to-water-to-air and a condo unit with a built-in heat recovery ventilator.", "source": "Dennis Campbell, 16-page specification, pages 1 to 13"},
    {"id": "L10", "tier": "source", "text": "A flow meter and entering and leaving water thermometers are supplied so system performance can be checked on site.", "source": "Dennis Campbell, design philosophy document, Flow Meter and Temperature Thermometers"},
    {"id": "L11", "tier": "source", "text": "The reversing valve directs refrigerant to either the air coil or the water coil to switch between heating and cooling; the TX valve regulates refrigerant flow.", "source": "Dennis Campbell, design philosophy document, Reversing Valve and TX Valve sections"}
  ],
  "transport_sections": {
    "summary": "Two transport sections are what the installer carries into the home. They are distinct from the internal subassemblies (blower tray, filter rack, control panel, condensate pan) that a technician removes for service after the unit is installed.",
    "sections": [
      {
        "id": "T1",
        "name": "Transport section 1: thermal core",
        "weight_note": "The heavier section. It holds the whole refrigerant circuit, so carry weight is set by the compressor and exchangers. No weight target is stated; it is an engineering deliverable and will not be an equal split with section 2.",
        "contains": ["Entire sealed refrigerant circuit: compressor, reversing valve, metering devices, filter-drier, source coaxial exchanger, optional desuperheater coil and the application exchanger (air coil, load-water exchanger, or both on the triple-function core)", "Stainless condensate pan directly under the air coil (air-configured and triple-function cores)", "Hydraulic strip with external unions for source water, and for load water on water-configured and triple-function cores", "Core-side isolation valves at the wet transport joint (water-configured cores)", "Base frame with isolation mounts, levelling feet and hand-holds", "Return-air opening with slide-out filter rack (air-configured and triple-function cores). Dedicated coil leaving-air passage to the dry joint, sealed by a bulkhead from the compressor, refrigerant piping and electrical space; coil-header penetrations sealed. Passage fit and leakage require validation."],
        "contains_by_app": {
          "w2a-v": ["Entire sealed refrigerant circuit: compressor, reversing valve, metering devices, filter-drier, source coaxial exchanger, optional desuperheater coil and the air coil", "Stainless condensate pan directly under the air coil", "Hydraulic strip with external unions for source water (and domestic hot water where fitted)", "Base frame with isolation mounts, levelling feet and hand-holds", "Return-air opening with slide-out filter rack. Dedicated coil leaving-air passage to the dry joint, sealed by a bulkhead from the compressor, refrigerant piping and electrical space; coil-header penetrations sealed. Passage fit and leakage require validation."],
          "w2a-h": ["Entire sealed refrigerant circuit: compressor, reversing valve, metering devices, filter-drier, source coaxial exchanger, optional desuperheater coil and the air coil", "Stainless condensate pan directly under the air coil, with overflow switch required on horizontal builds", "Hydraulic strip with external unions for source water (and domestic hot water where fitted)", "Base frame or hanger rails with isolation mounts and hand-holds", "End return-air opening with slide-out filter rack. Dedicated coil leaving-air passage to the dry joint, sealed by a bulkhead from the compressor, refrigerant piping and electrical space; coil-header penetrations sealed. Passage fit and leakage require validation."],
          "w2w": ["Entire sealed refrigerant circuit: compressor, reversing valve, metering devices, filter-drier, source coaxial exchanger, optional desuperheater coil and the load-water coaxial exchanger", "Hydraulic strip with unions for source and load water (and domestic hot water where fitted)", "Core-side isolation valves at the wet transport joint", "Base frame with isolation mounts, levelling feet and hand-holds"],
          "w2w2a": ["Entire sealed refrigerant circuit: compressor, reversing valve, metering devices, filter-drier, source coaxial exchanger, optional desuperheater coil, the air coil and the load-water coaxial exchanger (circuit arrangement undefined)", "Stainless condensate pan directly under the air coil", "Hydraulic strip with external unions for source and load water (and domestic hot water where fitted)", "Base frame with isolation mounts, levelling feet and hand-holds", "Return-air opening with slide-out filter rack. Dedicated coil leaving-air passage to the dry joint, sealed by a bulkhead from the compressor, refrigerant piping and electrical space; coil-header penetrations sealed. Passage fit and leakage require validation."]
        },
        "functional_modules": ["M1", "M3", "M5"],
        "internal_subassemblies": ["Filter rack (slide-out, no refrigerant work)", "Condensate pan and drain fitting (front access, no refrigerant work)", "Compressor, reversing valve, metering devices, coils (refrigerant recovery required)"]
      },
      {
        "id": "T2",
        "name": "Transport section 2: air-movement and control section",
        "weight_note": "The lighter section. It contains no refrigerant. On vertical builds its frame bears on the core's top rails through alignment pins; on horizontal builds it stands on its own frame beside the core.",
        "contains": ["ECM blower on a slide-out tray", "Supply plenum and duct collar", "Electrical and control compartment with its own door, above the core's condensate pan on vertical builds", "Protected connector block for blower, sensors, thermostat and compressor power", "Optional duct heater section flanged to the supply plenum; optional HRV section connected by field ductwork"],
        "functional_modules": ["M2", "M4", "M6"],
        "internal_subassemblies": ["Blower tray (slide-out after plug disconnect)", "Control panel and relays (own door)", "Duct heater or HRV section (whole-section removal after electrical isolation)"],
        "water_variant_name": "Transport section 2 (water-configured): hydraulic and control service section",
        "water_variant_contains": ["Service-side isolation valves, low-point drains and high-point air vents at the wet transport joint", "Flow meter and thermometer wells", "External circulator flanges", "Electrical and control compartment with its own door", "Own frame; stands beside the core"]
      }
    ],
    "joints": [
      {"id": "J-AIR", "name": "Dry gasketed air joint", "applies": ["w2a-v", "w2a-h", "w2w2a"], "crosses": "Conditioned air only, from the core's coil outlet into the blower section", "does_not_cross": "Refrigerant, condensate, water", "construction": "Flanged perimeter frame on both sections with a closed-cell gasket. Vertical builds: compressed by section 2's weight plus latches, located by alignment pins on the core top rails. Horizontal builds: the sections stand on their own frames and are drawn together by latches or bolts at the vertical flange", "validation": "Gasket material, compression, leakage at operating static pressure, latch rating"},
      {"id": "J-ELEC", "name": "Protected electrical connector", "applies": ["w2a-v", "w2a-h", "w2w", "w2w2a"], "crosses": "Line voltage to the compressor and low-voltage sensor and safety circuits", "does_not_cross": "Nothing else", "construction": "Keyed, latching connector blocks recessed behind a cover so they cannot be damaged in transport; disconnect is external to the unit", "validation": "Connector current rating, strain relief, listing"},
      {"id": "J-WET", "name": "Wet unions with isolation on both sides, drain and vent", "applies": ["w2w"], "crosses": "Source and load water between the core exchangers and the service section fittings", "does_not_cross": "Refrigerant", "construction": "A union on each of the four water lines with an isolation valve on the core side and on the service side, leaving a short drainable segment between them; low-point drains and high-point air vents on the service section. The core's exchangers stay filled behind their valves; only the trapped segment is drained before separation", "validation": "Union and valve size, material and pressure rating; drain and vent sizing; procedure for refilling and air removal; freeze protection of the filled core during transport or storage"},
      {"id": "J-LOAD", "name": "Structural bearing", "applies": ["w2a-v", "w2w2a"], "crosses": "Weight of section 2 into the core rails and base", "does_not_cross": "Loads are not carried by the gasket, ducts or connectors", "construction": "Section 2 frame rails bear on the core's top rails through alignment pins; each section stands on its own frame when separated", "validation": "Rail stiffness, pin shear, seismic restraint where required"}
    ],
    "arrangement_decision": {
      "chosen": "A",
      "options": [
        {"id": "A", "name": "Core on the floor, air section on top (draw-through)", "text": "The heavy core stays at floor level. Return air enters the core through the filter rack, crosses the air coil, then passes the dry air joint into the blower section, which discharges to the supply duct. The filter is upstream of the coil, the condensate pan stays with the coil, and the controls sit above the pan.", "status": "Chosen baseline", "why": "No refrigerant line crosses the transport joint; the heavier section is never lifted onto another section; condensate never crosses the joint."},
        {"id": "B", "name": "Blower section below, core on top (blow-through)", "text": "Return air enters the lower blower section and is pushed up through the coil in the core above.", "status": "Not chosen", "why": "The heavier core would have to be lifted onto the blower section during installation, and the condensate pan would sit above the blower and controls, against the legacy practice of keeping controls above the pan."},
        {"id": "C", "name": "Coil-only upper section with the compressor below", "text": "The air coil rides in the upper section and the compressor and water exchanger stay below.", "status": "Rejected for this concept", "why": "A refrigerant line would cross the transport joint, so separation would need a field refrigerant coupling or recovery. That cannot be shown as a dry joint and contradicts the sealed-circuit objective."}
      ]
    },
    "assembly_sequences": {
      "w2a-v": [
        {"step": 1, "name": "Bring both sections to the mechanical room", "text": "Each section moves on its own frame with hand-holds. The core is the heavier carry and sets the crew size; section 2 follows.", "t2": "apart"},
        {"step": 2, "name": "Place and level the core", "text": "Set the core on its isolation feet at the final position with service clearance in front and at the hydraulic strip.", "t2": "hidden"},
        {"step": 3, "name": "Connect water and condensate at the core", "text": "Source (and domestic hot water, where fitted) unions outside the cabinet; condensate trap on the pan drain. Circulators sit in the external piping, as in legacy practice.", "t2": "hidden", "paths": ["source", "condensate"]},
        {"step": 4, "name": "Lower section 2 onto the alignment pins", "text": "The pins locate the frames; the gasket compresses under the section's weight. Latches complete the joint. Loads pass rail to rail, not through the gasket.", "t2": "joining", "highlight": "joint"},
        {"step": 5, "name": "Mate the protected electrical connectors", "text": "Keyed connector blocks behind the cover join blower, sensors, thermostat and compressor power. The external disconnect stays open until checks are complete.", "t2": "joined", "highlight": "connector", "paths": ["electrical"]},
        {"step": 6, "name": "Connect ducts", "text": "Return duct to the core's filter rack opening; supply duct to section 2's collar, and to the duct heater or HRV ductwork where fitted.", "t2": "joined", "highlight": "ducts"},
        {"step": 7, "name": "Fill, purge, check and start", "text": "Water side filled and purged of air; joint inspected for air leakage; safeties proven; then the compressor is started and flow and temperatures are read at the supplied meter and thermometers.", "t2": "joined", "highlight": "checks", "paths": ["source", "load", "refrigerant", "electrical", "condensate"]}
      ],
      "w2a-h": [
        {"step": 1, "name": "Bring both sections to the space", "text": "Each section moves on its own frame with hand-holds. Horizontal sections are never stacked; both stand on their own supports.", "t2": "apart"},
        {"step": 2, "name": "Place, support and level the core", "text": "Set the core on its isolation feet or hanger rails at the final position, with the return opening and hydraulic strip accessible.", "t2": "hidden"},
        {"step": 3, "name": "Connect water and condensate at the core", "text": "Source (and domestic hot water, where fitted) unions outside the cabinet; condensate trap on the pan drain with the overflow switch required on horizontal builds.", "t2": "hidden", "paths": ["source", "condensate"]},
        {"step": 4, "name": "Bring section 2 end to end and draw the flange together", "text": "Section 2 stands on its own frame or hangers, is aligned to the core's vertical flange by guide pins, and is drawn onto the gasket with latches or bolts. Neither section carries the other's weight.", "t2": "joining", "highlight": "joint"},
        {"step": 5, "name": "Mate the protected electrical connectors", "text": "Keyed connector blocks behind the cover join blower, sensors, thermostat and compressor power. The external disconnect stays open until checks are complete.", "t2": "joined", "highlight": "connector", "paths": ["electrical"]},
        {"step": 6, "name": "Connect ducts", "text": "Return duct to the core's end filter opening; supply duct to section 2's end collar, and to the duct heater where fitted.", "t2": "joined", "highlight": "ducts"},
        {"step": 7, "name": "Fill, purge, check and start", "text": "Water side filled and purged of air; joint inspected for air leakage; safeties proven; then the compressor is started and readings taken.", "t2": "joined", "highlight": "checks", "paths": ["source", "load", "refrigerant", "electrical", "condensate"]}
      ],
      "w2w": [
        {"step": 1, "name": "Bring both sections to the mechanical room", "text": "The water-configured core and the hydraulic and control service section each move on their own frame with hand-holds.", "t2": "apart"},
        {"step": 2, "name": "Place and level the core", "text": "Set the core on its isolation feet with the wet-joint unions facing the service section position.", "t2": "hidden"},
        {"step": 3, "name": "Place the service section beside the core", "text": "Each service section stands beside its own core on a separate frame. Align the unions. The optional stacking frame supports two complete units; its structure and installation sequence require validation.", "t2": "joining"},
        {"step": 4, "name": "Make up the wet unions with both isolation valves closed", "text": "Four unions (source in and out, load in and out). Core-side and service-side valves stay closed so the trapped segment is dry until filling.", "t2": "joined", "highlight": "joint"},
        {"step": 5, "name": "Connect external piping and the connectors", "text": "Loop and load piping to the service section's circulator flanges; keyed connector blocks join controls to the compressor and sensors. Disconnect stays open.", "t2": "joined", "highlight": "connector", "paths": ["source", "load", "electrical"]},
        {"step": 6, "name": "Fill, vent and purge", "text": "Open the service-side valves, fill slowly, open high-point vents until they run clear, then open the core-side valves and verify flow at the meter.", "t2": "joined", "highlight": "wet"},
        {"step": 7, "name": "Check and start", "text": "Safeties proven; compressor started; entering and leaving temperatures and flow compared with the design.", "t2": "joined", "highlight": "checks", "paths": ["source", "load", "refrigerant", "electrical"]}
      ],
      "w2w2a": [
        {"step": 1, "name": "Bring both sections to the mechanical room", "text": "The triple-function core is the heaviest core in the family because it carries two water exchangers and the air coil; section 2 is the air-only section.", "t2": "apart"},
        {"step": 2, "name": "Place and level the core", "text": "Set the core on its isolation feet with service clearance in front and at the hydraulic strip.", "t2": "hidden"},
        {"step": 3, "name": "Connect source, load, condensate and domestic hot water at the core", "text": "All water circuits end at external unions on the core's strip; the condensate trap goes on the pan drain. No water crosses the transport joint.", "t2": "hidden", "paths": ["source", "load", "condensate"]},
        {"step": 4, "name": "Lower the air section onto the alignment pins", "text": "Pins locate the frames; the gasket compresses under the section's weight; latches complete the joint.", "t2": "joining", "highlight": "joint"},
        {"step": 5, "name": "Mate the protected electrical connectors", "text": "Keyed connector blocks join blower, sensors, thermostat and compressor power. Disconnect stays open.", "t2": "joined", "highlight": "connector", "paths": ["electrical"]},
        {"step": 6, "name": "Connect ducts", "text": "Return duct to the core's filter rack opening; supply duct to the air section's collar, and to the duct heater where fitted.", "t2": "joined", "highlight": "ducts"},
        {"step": 7, "name": "Fill, purge, check and start", "text": "Both water circuits filled and purged; joint inspected; safeties proven; compressor started and readings taken.", "t2": "joined", "highlight": "checks", "paths": ["source", "load", "refrigerant", "electrical", "condensate"]}
      ]
    },
    "water_separation_procedure": ["Isolate power at the external disconnect", "Close the isolation valves on both sides of each wet union (core side and service side)", "Open the separate T2 service-side drain and vent on each of the four trapped union segments and collect the water; core nipples must pitch toward those drains without pockets. The core exchangers and external piping stay filled behind their valves; drain-down completeness requires validation", "Break the unions and move the service section away on its own frame", "On reassembly: make up the unions, open the high-point vents, open the service-side valves and fill slowly, purge air until the vents run clear, open the core-side valves, then verify flow at the meter"]
  },
  "modules": [
    {
      "code": "M1",
      "id": "rs",
      "name": "Sealed refrigeration circuit",
      "role": "common",
      "in_section": "T1",
      "summary": "The whole refrigerant circuit, factory brazed, charged and sealed inside the thermal core. It includes the application exchanger (air coil, load-water exchanger, or both on the triple-function core), so it is built for one application and is not field-convertible. It has no field refrigerant joints and no refrigerant line crosses the transport joint.",
      "variants": [
        {"id": "rs-a", "name": "M1-A air-configured core", "for": ["w2a-v", "w2a-h"], "text": "Application exchanger is a finned air coil inside the core, with the condensate pan beneath it."},
        {"id": "rs-w", "name": "M1-W water-configured core", "for": ["w2w"], "text": "Application exchanger is a second coaxial water heat exchanger; both water circuits end at unions on the core."},
        {"id": "rs-t", "name": "M1-T triple-function core", "for": ["w2w2a"], "text": "A dedicated sealed core with an air coil, a load-water exchanger and its own load and source unions on the strip. It pairs with the air-only section 2 across the dry air joint. The refrigerant circuit arrangement for two load exchangers is undefined and is the largest open engineering item in the concept."}
      ],
      "contents": ["Scroll or rotary compressor on isolation mounts", "Reversing valve", "Bi-directional metering arrangement for each heat exchanger with the filter-drier in the common liquid line (arrangement to be validated)", "Coaxial source-water heat exchanger, copper or copper-nickel", "Optional desuperheater coil (double-wall)", "Application heat exchanger per variant", "High- and low-pressure switches"],
      "service_boundary": "Sealed. Any work on this circuit is refrigerant service requiring recovery, evacuation and recharge by a licensed technician. It is reachable from the core's front and side panels; it is never separated at the transport joint.",
      "legacy_refs": ["L6", "L7", "L11"],
      "validation": ["Factory-charged sealed circuit with no field joints", "Metering arrangement for reversing operation", "Refrigerant class, charge and compartment sealing (ASHRAE 15 and UL 60335-2-40 to be assessed)", "Oil return and trap geometry for horizontal builds", "Triple-function circuit design"],
      "color": "#c9512b"
    },
    {
      "code": "M2",
      "id": "app",
      "name": "Air-movement or hydraulic service equipment",
      "role": "application",
      "in_section": "T2 (filter rack and condensate pan stay on T1)",
      "summary": "The non-refrigerant equipment that gives the unit its application. On air and triple-function builds the blower and supply collar live in section 2 across the dry air joint; the filter rack and condensate pan stay on the core because they belong with the coil. On water-to-water builds the valves, drains, vents, meters and circulator flanges form the hydraulic service section.",
      "variants": [
        {"id": "m2a", "name": "M2-A air-movement equipment", "for": ["w2a-v", "w2a-h", "w2w2a"], "text": "ECM blower on a slide-out tray and supply plenum in section 2; slide-out filter rack at the core's return opening; stainless condensate pan under the coil in the core."},
        {"id": "m2w", "name": "M2-W hydraulic service equipment", "for": ["w2w"], "text": "Service-side isolation valves, drains, air vents, flow meter, thermometer wells and external circulator flanges in the service section, joined to the core at the wet unions."}
      ],
      "contents": ["ECM blower and motor (air)", "Supply plenum and collar (air)", "Filter rack at the core return opening (air)", "Stainless condensate pan with drain, in the core (air)", "Isolation valves, drains and air vents (water)", "Flow meter and thermometer wells (water)"],
      "service_boundary": "Blower tray, filters, condensate pan and hydraulic fittings are removable without refrigerant work. Air-coil work is refrigerant service on the core.",
      "legacy_refs": ["L3", "L5", "L10"],
      "validation": ["Blower slide-out clearance and weight", "Condensate pan slope and overflow protection for horizontal builds", "Air-side static pressure with filters and optional sections", "Drain, vent and refill procedure for the wet joint"],
      "color": "#2584ba"
    },
    {
      "code": "M3",
      "id": "hyd",
      "name": "Hydraulic strip",
      "role": "common",
      "in_section": "T1",
      "summary": "A fixed connection strip on the core carrying every water and condensate penetration through grommets. Pressurized field joints are unions or flanges outside the cabinet, never at the grommet. On water-to-water builds the unions, with isolation valves on both sides, are the wet transport joint to the service section.",
      "variants": [],
      "contents": ["Source water in and out", "Load water in and out (water-configured and triple-function cores)", "Domestic hot water in and out (desuperheater option)", "Condensate drain (air-configured and triple-function cores)", "Core-side isolation valves (water-configured cores)", "Pipe grommets at each penetration"],
      "service_boundary": "External unions allow the core to be isolated and disconnected without cutting pipe. Circulators sit in the external piping, following legacy practice.",
      "legacy_refs": ["L2", "L5"],
      "validation": ["Connection sizes, materials and pressure ratings", "One strip layout serving air, water, horizontal and triple-function cores", "Relief valve, high limit and flow proving on the desuperheater circuit"],
      "color": "#1c8c7a"
    },
    {
      "code": "M4",
      "id": "ctl",
      "name": "Electrical and control compartment",
      "role": "common",
      "in_section": "T2",
      "summary": "A separate compartment with its own door in section 2. On vertical builds it sits above the core's condensate pan and drains, which reduces its exposure to condensate leaks; pan overflow protection and compartment isolation remain design considerations. It is separated from the refrigerant space by the transport joint. Standard relays and a generic anti-short-cycle board follow the legacy philosophy. Power to the compressor crosses the joint through the protected connector.",
      "variants": [],
      "contents": ["Compressor contactor and relays", "Low-voltage transformer", "Anti-short-cycle and lock-out board (generic, off the shelf)", "Terminal strip for thermostat and accessories", "Required protective devices: high- and low-pressure cutouts, source flow or freeze protection, condensate overflow switch on horizontal builds, duct heater airflow proving and limits interlocked with the blower"],
      "service_boundary": "Own door. Line-voltage disconnect is external to the unit.",
      "legacy_refs": ["L1", "L4"],
      "validation": ["Protective device schedule and listing", "Separation between electrical compartment and refrigerant space", "Connector rating across the transport joint", "Wiring diagram in the legacy full-colour style"],
      "color": "#d59a1f"
    },
    {
      "code": "M5",
      "id": "enc",
      "name": "Frames and enclosure",
      "role": "common",
      "in_section": "T1 and T2 (each section has its own frame)",
      "summary": "Each transport section has its own frame so it stands and travels on its own. The core frame carries isolation mounts and levelling feet. On vertical builds section 2's frame bears on the core's top rails through alignment pins; on horizontal and water-to-water builds section 2 stands on its own supports beside the core. Powder-coated galvanized panels, 1-inch acoustic lining and removable front and side panels follow legacy construction.",
      "variants": [
        {"id": "enc-v", "name": "Vertical: section 2 on top of the core", "for": ["w2a-v"], "text": "Dry air joint is horizontal at the top of the core."},
        {"id": "enc-vt", "name": "Proposed taller vertical packaging: air section above a triple-function core", "for": ["w2w2a"], "text": "Same joint as vertical; load and source unions on the core's strip. Section heights are undefined; the taller packaging is proposed pending layout validation."},
        {"id": "enc-h", "name": "Horizontal: sections end to end", "for": ["w2a-h"], "text": "Dry air joint is vertical between the core and the blower section; each section on its own supports; end discharge assumed."},
        {"id": "enc-w", "name": "Low water-to-water: service section beside the core", "for": ["w2w"], "text": "Wet unions between the sections; each on its own frame; stackable as two complete units on a frame requiring structural rating."}
      ],
      "contents": ["Core base frame with isolation mounts, levelling feet and hand-holds", "Section 2 frame with alignment sockets and hand-holds", "Galvanized, powder-coated panels", "1-inch acoustic lining", "Removable front and side panels", "Joint flanges and latches"],
      "service_boundary": "Panels are removable without tools on the concept; fastener type is undefined.",
      "legacy_refs": ["L2"],
      "validation": ["Acoustic lining flame spread, erosion and acoustic performance", "Panel stiffness and vibration", "Structural load path through the joint, and for stacking and seismic restraint", "Envelope, doorway and stairway clearance targets and carry weight per section"],
      "color": "#5a6c79"
    },
    {
      "code": "M6",
      "id": "exp",
      "name": "Optional sections",
      "role": "optional",
      "in_section": "T2, field ductwork, or a separate frame for stacking",
      "summary": "Field-attachable sections that contain no refrigerant joints. Each one must satisfy the compatibility rules and adds its own protective devices and electrical coordination.",
      "variants": [
        {"id": "dsh", "name": "Desuperheater domestic hot water tie-in", "for": ["w2a-v", "w2a-h", "w2w", "w2w2a"], "text": "A factory option inside the core plus domestic hot water ports on the strip. Ordered only when a domestic hot water circuit exists."},
        {"id": "heater", "name": "Electric duct heater section", "for": ["w2a-v", "w2a-h", "w2w2a"], "text": "Supply-side add-on flanged to section 2's plenum, with airflow proving and redundant limits interlocked with the blower."},
        {"id": "hrv", "name": "Heat recovery ventilator section", "for": ["w2a-v"], "text": "A separate section connected by field ductwork on both sides: fresh air is delivered into the core's return path upstream of the filter, and stale air is drawn from the return or supply path as the balancing design requires; outdoor air and exhaust collars are on the HRV. It follows the legacy condo family with a built-in HRV but is not shown as a supply-only attachment."},
        {"id": "stack", "name": "Stacking frame for a second complete unit", "for": ["w2w"], "text": "Two complete, independently protected water-to-water units on a frame requiring structural rating. It is not capacity doubling of one circuit."}
      ],
      "contents": ["Duct heater section", "HRV section with field ductwork to return and supply", "Stacking frame", "Domestic hot water ports"],
      "service_boundary": "Each section is removable as a whole after electrical isolation.",
      "legacy_refs": ["L7", "L8", "L9"],
      "validation": ["Structural load path, seismic restraint and electrical coordination for stacked units", "Added static pressure against ECM blower capability", "Combined refrigerant charge in one room for stacked units", "HRV balancing, defrost and duct routing"],
      "color": "#7c4dbe"
    }
  ],
  "applications": [
    {"id": "w2a-v", "name": "Water-to-air, vertical", "legacy_family_examples": ["PBSM", "PBVE", "PBMC", "PBSC"], "refrigeration_variant": "rs-a", "application_variants": ["m2a"], "enclosure": "enc-v", "load_medium": "air", "sections": "T1 thermal core on the floor; T2 air-movement and control section on top across the dry air joint.", "text": "Forced-air heating and cooling from a vertical cabinet delivered as two stacked sections."},
    {"id": "w2a-h", "name": "Water-to-air, horizontal", "legacy_family_examples": ["PBHS", "PHHS"], "refrigeration_variant": "rs-a", "application_variants": ["m2a"], "enclosure": "enc-h", "load_medium": "air", "sections": "T1 thermal core and T2 air-movement section end to end across a vertical dry air joint, each on its own supports.", "text": "Low-profile forced-air unit. Legacy horizontal families are split systems with a separate air handler; the concept keeps both sections dry-joined instead of a field refrigerant line set."},
    {"id": "w2w", "name": "Water-to-water", "legacy_family_examples": ["PBWW"], "refrigeration_variant": "rs-w", "application_variants": ["m2w"], "enclosure": "enc-w", "load_medium": "water", "sections": "T1 water-configured thermal core; T2 hydraulic and control service section beside it, joined at wet unions with isolation valves on both sides, drains and vents.", "text": "Hot or chilled water to a hydronic load. The core is application-specific: it does not accept an air section."},
    {"id": "w2w2a", "name": "Water-to-water-to-air (triple function)", "legacy_family_examples": ["PBST", "PBWW water-to-water-to-air"], "refrigeration_variant": "rs-t", "application_variants": ["m2a"], "enclosure": "enc-vt", "load_medium": "air and water", "sections": "T1 dedicated triple-function core with source and load unions on its own strip; T2 air-only section on top across the dry air joint. No wet joint.", "text": "Hydronic and forced-air loads from one unit. The section split is shown; the refrigeration circuit for this core is undefined."}
  ],
  "source_options": [
    {"id": "closed", "name": "Closed loop, copper source exchanger", "legacy_ref": "L6", "text": "Ground loop with antifreeze; external circulator in the loop piping."},
    {"id": "open", "name": "Open loop, copper-nickel source exchanger", "legacy_ref": "L6", "text": "Well or surface water; copper-nickel chosen for corrosion resistance. Water quality limits are not defined in the concept."}
  ],
  "options": [
    {"id": "dsh", "name": "Desuperheater with domestic hot water tie-in", "requires_any": ["w2a-v", "w2a-h", "w2w", "w2w2a"], "excludes": [], "adds_hydraulic_ports": ["Domestic hot water in", "Domestic hot water out"], "adds_other_connections": [], "adds_devices": ["Relief valve, high limit and flow proving on the domestic circuit (to be specified)"], "legacy_ref": "L7"},
    {"id": "heater", "name": "Electric duct heater section", "requires_any": ["w2a-v", "w2a-h", "w2w2a"], "excludes": [], "adds_hydraulic_ports": [], "adds_other_connections": ["Supply duct flange on the duct heater section"], "adds_devices": ["Airflow proving switch and redundant high limits interlocked with the blower"], "legacy_ref": "L8"},
    {"id": "hrv", "name": "Heat recovery ventilator section", "requires_any": ["w2a-v"], "excludes": ["stack"], "adds_hydraulic_ports": [], "adds_other_connections": ["Outdoor air and exhaust duct collars on the HRV section", "Field duct connections to the core return path and the section 2 supply path"], "adds_devices": ["HRV defrost and fan interlock"], "legacy_ref": "L9"},
    {"id": "stack", "name": "Stacking frame, second complete unit", "requires_any": ["w2w"], "excludes": ["hrv"], "adds_hydraulic_ports": [], "adds_other_connections": ["Second complete unit with its own source and load unions on its own core"], "adds_devices": ["Independent protective devices on each unit"], "legacy_ref": "L9"}
  ],
  "rules": [
    {"id": "R1", "text": "The thermal core is built for one application at the factory (air, water, or triple function) and is not field-convertible; the air section and the hydraulic service section do not interchange on the same core.", "why": "The application heat exchanger is inside the sealed refrigerant circuit."},
    {"id": "R2", "text": "No refrigerant line crosses the transport joint; only air, water (water-to-water builds) and protected electrical connections do.", "why": "Separation must not require refrigerant recovery or a field refrigerant coupling."},
    {"id": "R3", "text": "Duct heater and HRV sections require an air-configured or triple-function core with the air-movement section.", "why": "Both act on the supply, return or ventilation airstream."},
    {"id": "R4", "text": "The HRV section is limited to vertical water-to-air builds.", "why": "It follows the legacy vertical condo family; horizontal duct geometry is undefined."},
    {"id": "R5", "text": "Stacking applies to water-to-water builds only, as two complete units.", "why": "No air path crosses the stack, and each unit keeps its own protected circuit."},
    {"id": "R6", "text": "Triple function uses the dedicated M1-T core with proposed taller vertical packaging, pending layout validation of section heights.", "why": "Two load exchangers plus the air coil are a different sealed core, not a bolt-on to the air-configured core."},
    {"id": "R7", "text": "The desuperheater option adds domestic hot water ports and protective devices; it is not fitted where no domestic circuit exists.", "why": "Avoids a water dead-leg and unrelieved trapped volume."},
    {"id": "R8", "text": "Every pressurized field joint is outside the cabinet at a union or flange; grommets are penetrations only.", "why": "Keeps leaks outside the electrical zone and lets the unit be disconnected without cutting pipe."}
  ],
  "interfaces": [
    {"id": "I1", "between": "T2 to T1 (J-AIR)", "medium": "Conditioned air", "concept": "Flanged perimeter frames with a closed-cell gasket; alignment pins (vertical) or guide pins and latches (horizontal)", "factory_or_field": "Field, dry", "sealed": "Air gasket", "validate": "Gasket compression and leakage at operating static, latch rating"},
    {"id": "I2", "between": "T2 to T1 (J-ELEC)", "medium": "Line and low voltage", "concept": "Keyed, latching connector blocks recessed behind a cover", "factory_or_field": "Field, plug", "sealed": "n/a", "validate": "Connector current rating, strain relief, listing"},
    {"id": "I3", "between": "T2 to T1 (J-LOAD, vertical builds)", "medium": "Structural", "concept": "Section 2 rails bear on core rails through pins; each section has its own frame", "factory_or_field": "Field", "sealed": "n/a", "validate": "Rail stiffness, pin shear, seismic restraint"},
    {"id": "I4", "between": "T2-W to T1-W (J-WET)", "medium": "Source and load water", "concept": "Unions with isolation valves on the core side and the service side; each of four trapped segments has its own drain and vent on the T2 side of the union. Core nipples pitch toward the service drains; complete drain-down requires validation", "factory_or_field": "Field, wet (trapped segment drained before separation)", "sealed": "Open water circuit", "validate": "Union and valve size, material, pressure rating; refill and air-removal procedure; freeze protection of the filled core"},
    {"id": "I5", "between": "M1 to M2-A (inside T1)", "medium": "Refrigerant (air coil)", "concept": "Air coil is part of the sealed core; the condensate pan sits under it", "factory_or_field": "Factory brazed", "sealed": "Sealed", "validate": "Coil access for recovery-based service, condensate carry-over"},
    {"id": "I6", "between": "M1 to M3", "medium": "Source water", "concept": "Type L copper stubs through grommets to external unions", "factory_or_field": "Field joint outside cabinet", "sealed": "Open water circuit", "validate": "Connection size, material, pressure rating, freeze protection"},
    {"id": "I7", "between": "M1 to M3", "medium": "Domestic hot water (option)", "concept": "Double-wall desuperheater stubs to bronze external fittings", "factory_or_field": "Field joint outside cabinet", "sealed": "Open water circuit", "validate": "Relief valve, high limit, flow proving, scald protection"},
    {"id": "I8", "between": "Condensate pan to M3", "medium": "Condensate", "concept": "Stainless pan drain through a grommet to an external trap; pan and coil both in T1", "factory_or_field": "Field", "sealed": "Gravity drain", "validate": "Pan slope, trap depth, overflow switch on horizontal builds"},
    {"id": "I9", "between": "M4 to M1 (through J-ELEC)", "medium": "Line and low voltage", "concept": "Contactor to compressor and pressure switches to control circuit through the joint connector", "factory_or_field": "Field, plug", "sealed": "Bulkhead on the core side", "validate": "Compartment separation from refrigerant space"},
    {"id": "I10", "between": "M4 to field", "medium": "Line and low voltage", "concept": "External disconnect; thermostat and accessory terminal strip", "factory_or_field": "Field", "sealed": "n/a", "validate": "Disconnect rating, terminal labelling"},
    {"id": "I11", "between": "M6 heater to T2 and M4", "medium": "Air and electrical", "concept": "Supply-side flanged section with proving switch and limits wired to M4", "factory_or_field": "Field", "sealed": "n/a", "validate": "Airflow proving, limit redundancy, added static pressure"},
    {"id": "I12", "between": "M6 HRV to T1 return path and T2 supply path", "medium": "Air", "concept": "Separate HRV section joined by field ductwork: fresh-air duct into the core's return-air path upstream of the filter rack, stale-air duct from the return or supply path per the balancing design, outdoor and exhaust collars on the HRV", "factory_or_field": "Field ductwork", "sealed": "n/a", "validate": "Balancing, defrost, condensate handling in the HRV core, duct routing"},
    {"id": "I13", "between": "M6 stacking frame to M5", "medium": "Structural", "concept": "Frame requiring structural rating, carrying a second complete two-section unit", "factory_or_field": "Field", "sealed": "n/a", "validate": "Load path, seismic restraint, service clearance to the upper unit"}
  ],
  "paths": [
    {"id": "refrigerant", "label": "Refrigerant (sealed in the core)", "color": "#c9512b"},
    {"id": "source", "label": "Source water", "color": "#1c8c7a"},
    {"id": "load", "label": "Load air or water", "color": "#2584ba"},
    {"id": "condensate", "label": "Condensate", "color": "#7fa6bd"},
    {"id": "electrical", "label": "Electrical and control", "color": "#d59a1f"}
  ],
  "service_paths": [
    {"item": "Air filters", "path": "Slide-out rack at the core return opening, no tools", "refrigerant_work": false},
    {"item": "Blower tray", "path": "Section 2 front, slide-out after panel removal and plug disconnect", "refrigerant_work": false},
    {"item": "Controls and relays", "path": "Own door on section 2, no other compartment opened", "refrigerant_work": false},
    {"item": "Condensate pan", "path": "Core front panel, below the coil", "refrigerant_work": false},
    {"item": "External circulators and unions", "path": "Outside the cabinet", "refrigerant_work": false},
    {"item": "Hydraulic service section (water-to-water)", "path": "Isolate both sides, drain the trapped segments, break unions, move the section away", "refrigerant_work": false},
    {"item": "Air coil", "path": "Core front and side panels; refrigerant recovery required", "refrigerant_work": true},
    {"item": "Compressor, reversing valve, metering devices", "path": "Core front and side panels; refrigerant recovery required", "refrigerant_work": true}
  ],
  "not_claimed": [
    "No capacity, efficiency, sound, carry-weight or service-time figures are stated for the concept.",
    "No cabinet dimensions, doorway clearances, connection sizes, pressure ratings or electrical ratings are defined, so fit through any particular opening is not demonstrated.",
    "No safety listing, AHRI or ISO 13256 rating, or field trial exists.",
    "The concept is not orderable; there is no quotation or lead time."
  ]
}