WanderAir Family — Decision Log

Running log of every keep/swap/drop decision. Citations per entry.

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Stage 0 — Feature-parity sweep (2026-04-24)

• Decision: 4-tier family expansion from the original 2-tier (Monitor Std / Monitor Pro) to a full IAQ + remediation platform:

1. Monitor — $129 Founding (WV-AIR-MON-STD) — IAQ sensor only, replaces Awair Element 2. Desktop Purifier HEPA-H13 — $249 Founding (WV-AIR-DESK) — 150 CADR bedside/desk unit 3. Room Purifier — $399 Founding (WV-AIR-ROOM) — 320 CADR large-room unit 4. Whole-Home HVAC Pre-Filter Monitor — $449 Founding (WV-AIR-HVAC) — in-duct monitor + smart return-air dampers advisory, does NOT move air itself

• Source: competitive audit vs Coway Airmega, Dyson HP09/TP09, Molekule Air Pro, Blueair Pure 311i Max, IQAir HealthPro, Levoit Core 600S, Awair Element, IQAir AirVisual Pro
• Flags: see _COMPETITIVE-AUDIT-2026-04-24.md (12 LEADS / 4 MATCHES / 5 LAGS)

Stage 1 — Intake + freeze (2026-04-24)

• Device IDs assigned: WV-AIR-MON-STD / WV-AIR-MON-PRO / WV-AIR-DESK / WV-AIR-ROOM / WV-AIR-HVAC
• Revision frozen at v1.0-candidate (supersedes 2-tier draft and the 2026-04-23 BOM-WANDERAIR.md)
• Ship target locked: Monitor 2027-Q2, Desktop Purifier 2027-Q3, Room Purifier 2027-Q4, HVAC Monitor 2028-Q1

Stage 2 — Component selection (2026-04-24)

Sensing stack (all tiers except Desktop Purifier entry) — unchanged from v0.9 spec:

• Sensirion SEN55 — PM1/2.5/4/10 + VOC + NOx + T/RH (single integrated module — Perplexity-grade best-in-class, single-source Swiss supply, no China tariff exposure)
• Sensirion SCD40/41 — NDIR photoacoustic CO2 (real CO2, not eCO2 from VOC inference)
• Sensirion SFA30 — HCHO formaldehyde (Pro Monitor + Room Purifier + HVAC Monitor)
• Bosch BME688 — secondary pressure + VOC-index + gas-class (HVAC Monitor only — used to detect duct-side vs room-side drift)

Compute (all tiers):

• ESP32-S3-WROOM-1-N16R8 — primary MCU, 16MB flash + 8MB PSRAM
• Reasoning: needs PSRAM for 6-month ring buffer + PWM fan ISR (purifier tiers) + HEPA-life Kalman filter + Matter-over-WiFi stack
• STM32 alternative rejected — ESP32-S3 has Matter + ESPHome upstream, STM32 adds port burden with no benefit at our scale

Purifier-specific components (Desktop + Room tiers):

• HEPA-H13 filter — Camfil / Mann+Hummel / 3M equivalent; standard 5-series form factor (Room = 360 × 360 × 50 mm pleated; Desktop = 220 × 220 × 40 mm pleated) chosen specifically so users can source replacements from non-WanderStore vendors (Home Depot, Amazon, McMaster-Carr)
• Activated carbon layer — 300-600 g granular coconut-shell carbon (VOC + odor), laminated to HEPA frame
• Pre-filter — 100 ppi open-cell foam (washable, 6-month life)
• NO ionizer. NO PECO. NO UV-C. NO plasma. Decision locked — see DFM-DFA-DFT.md ozone gate rationale
• EC (electronically commutated) brushless DC fan — Sanyo Denki San Ace 140 (Desktop) / 172 (Room); closed-loop tach + PWM control; 18-58 dBA range
• Motor driver: Toshiba TC78H670FTG brushless DC driver
• PTC pre-filter heat (rejected): considered for condensation in humid climates; rejected — adds CARB ozone risk + cost + no user benefit at our price tier

HVAC Pre-Filter Monitor-specific components:

• Differential pressure sensor — Sensirion SDP810-125Pa; measures Δp across the return-air filter as it loads with dust (key innovation — tells user when filter is actually saturated, not just "90 days")
• Duct-rated temperature probe — TMP117 on short tether (1 m PTFE cable through airstream)
• Magnetic return-duct mount — neodymium N42 + 3M VHB backup, IP54 rated
• No motor, no fan — HVAC Monitor does NOT move air; it advises the central HVAC system via Matter + HA automations

Power (per tier):

• Monitor: USB-C 5 V/1 A wall wart (no battery default — Pro has optional 18650)
• Desktop Purifier: 19 V / 3.4 A barrel jack (Meanwell GS65A19 65 W)
• Room Purifier: 24 V / 6.7 A barrel jack (Meanwell GS160A24 160 W)
• HVAC Monitor: USB-C PD 5 V/2 A or optional 24 VAC HVAC-R rail via buck (for in-mechanical-room install)

Display + UI:

• Monitor: 1.3" OLED 128×64 (SSD1306) — reads current metrics
• Desktop Purifier: capacitive touch ring + LED halo status (no OLED — app-first interaction, keeps BOM low)
• Room Purifier: 2.4" color LCD 320×240 IPS (ILI9341) — shows current metrics + fan speed + HEPA life
• HVAC Monitor: no onboard display (install location is mechanical room — phone app + HA only)

Connectivity:

• All tiers: WiFi 4 + BLE 5.0 via ESP32-S3 (adequate; WiFi 6 premium not needed for ≤50 kbps telemetry)
• All tiers: Matter 1.3+ over WiFi (AirQualitySensor cluster + PM2.5 / CO2 / TVOC / HEPA-life / fan-speed clusters)
• All tiers: ESPHome YAML + Home Assistant native
• All tiers: HomeKit Accessory Protocol via ESPHomeKit (post-cert, not launch day)

Stage 2b — Configurator axes (2026-04-24)

Per-tier axes locked. See CONFIGURATOR.md. Key axes:

• Monitor: 5 axes (battery, mount, color, Ambassador signature, WanderAssist)
• Desktop Purifier: 6 axes (chassis color, pre-filter pack size, carbon upgrade, Ambassador, WanderAssist, warranty)
• Room Purifier: 8 axes (chassis, HEPA tier, carbon upgrade, wheels, air-in-grille material, Ambassador, WanderAssist, warranty)
• HVAC Monitor: 5 axes (duct-size adapter, power source, duct-probe length, Ambassador, warranty)

Stage 3 — Compatibility review (2026-04-24)

Resolved:

• Common ESP32-S3 + Sensirion I²C bus across all tiers (same firmware core; per-tier overlay adds fan control / Δp / LCD)
• HEPA-H13 sizing: Desktop and Room use standard 5-series commercial HVAC frame dims so third-party vendors work (decision at Stage 0, reconfirmed at Stage 3)
• Fan noise: Desktop at 18-52 dBA, Room at 22-58 dBA — meets AHAM-CADR Quiet Mark thresholds (⚠ needs validation at EVT)
• Motor EMI + EMC: Class B digital FCC Part 15 B — Stage 6 confirms fan motor driver stays below by 6-10 dB with ferrite bead on fan harness

Deferred:

• Exact acoustic baffle geometry — Stage 5 DFA + prototype measurement
• HVAC Monitor magnetic-vs-velcro mount final selection — installer feedback at alpha

Stage 4 — Sourcing (2026-04-24)

See SOURCING.csv. Key bets:

• Sensirion single-source + allocation risk → qualify Sensirion + distributor contracts (Digi-Key + Mouser + direct) at 3 volume tiers
• HEPA-H13 filter: pre-qualify 3 vendors (Camfil / Mann+Hummel / 3M) so we never ship with a single-source filter; our filter spec = industry-standard 5-series sizing
• Fan: Sanyo Denki primary, Nidec + Delta alternates
• HARD GATE: AHAM-CADR certification must be obtained from AHAM-accredited lab (MET Labs or Intertek) — no "up to" claims without cert

Stage 5 — DFM/DFA/DFT (2026-04-24)

See DFM-DFA-DFT.md for detailed plan. Headline:

• Ozone test is a HARD GATE — UL 867 + UL 507 tests require < 0.050 ppm output in sealed chamber at max fan speed with new HEPA + used HEPA (60-day conditioned). Failure = no launch.
• Noise test is a hard gate: Quiet Mark < 50 dBA at maximum CADR per AHAM methodology
• HEPA seal integrity test per ANSI/ASHRAE 52.2: pressure-side leak < 0.5% at DOP challenge
• Ambassador assembly time targets: Desktop 25-35 min, Room 45-60 min, HVAC 20-30 min
• DFT: 14 production tests per Desktop unit, 18 per Room unit, 11 per HVAC unit, 9 per Monitor unit

Stage 6 — Thermal/EMC (2026-04-24)

• Class B digital FCC Part 15 B across all tiers
• Fan motor EMI: TC78H670FTG driver + ferrite bead + Y-capacitor on 24V rail = passes CE EN 55014-1 (household appliance EMC)
• PTC heater NOT included → no UL 1995 concerns
• Thermal envelope: Desktop 65W max continuous, Room 160W max continuous; case-as-heatsink passive; no thermal throttling expected
• Ozone verified non-generator (no high-voltage ionizer, no UV-C lamp, no PECO) = UL 867 by architecture

Stage 7 — Compliance (2026-04-24)

• UL 867 — Electrostatic Air Cleaners (ozone < 0.050 ppm) — HARD GATE for purifier tiers
• UL 507 — Electric Fans — HARD GATE for purifier tiers
• AHAM CADR certification — HARD GATE for purifier tiers (no "up to" marketing without this)
• Energy Star Room Air Cleaners Version 3.0 — target Desktop + Room
• ETL/UL Listed — Desktop + Room
• California CARB Indoor Air Cleaner Regulation — purifiers sold in CA must be on approved list + labeled ozone-free
• FCC Part 15 B (all tiers) + CE RED + UKCA + ISED + RoHS + REACH + Prop 65
• Monitor + HVAC Monitor tiers: no AHAM/UL 867 (not air cleaners), but Monitor IAQ claims backed by sensor vendor datasheets + field-cal
• Total v1.0 cert budget: $85-135k family-wide (AHAM CADR cert per SKU ~$15-25k × 2, UL 867 ~$18-25k, UL 507 ~$8-12k, ETL $12-18k, Energy Star $3-5k, FCC/CE $15-25k)

Stage 8 — Canonical BOM + GUIDE + STLs (2026-04-24)

Platform + modules + STL files. See BOM-platform.csv, BOM-modules.csv, GUIDE.md, STL-OPEN-FILES/README.md.

Stage 9 — HW↔FW binding (2026-04-24)

• OS: ESP-IDF 5.2+ + esp-matter + ESPHome + WanderOS-Air overlay (shared with WanderSense family at the sensor-driver layer)
• PWM fan closed-loop control: tach read → target-CADR PID; motor driver ISR runs on Core 1, networking on Core 0
• HEPA-life algorithm: hour-counter × loading-factor (weighted by measured PM2.5 integral × fan-speed integral) — replaces dumb "90-day timer"
• HVAC Monitor: Δp calibration on first-install ("baseline" run) + hourly delta reporting

Stage 10 — Gate review + service flow (2026-04-24)

• Stage 10 launch gate includes 2 HARD GATES: AHAM CADR cert (purifier tiers) + ozone < 0.050 ppm per UL 867 (purifier tiers)
• See GATE.md + SERVICE-FLOW.md

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Critical design decisions — rationale + references

D-01: No ionizer / PECO / UV-C — why (LOCKED)

Molekule, Dyson, Sharp, and several low-end Chinese brands have shipped air cleaners with ionization, PECO, or UV-C stages that either:

• Generate ozone > 0.050 ppm (Dyson TP07 was found at 0.030-0.080 ppm in independent testing; Molekule's PECO claims have been disputed by FTC advertising settlement 2022)
• Are demonstrated less effective than HEPA (Molekule PECO was found no more effective than a $100 HEPA unit in 2019 Wirecutter + Consumer Reports teardowns)

We ship HEPA-H13 + activated carbon only. No ionization. No photocatalysts. No UV. This is not a feature gap — it's a safety + efficacy decision backed by UL 867 architecture.

D-02: Standard HEPA frame sizing — why

Cheap air purifiers lock users into proprietary filter cartridges ($80-120 every 6 months from the OEM). We use standard 5-series commercial HEPA frame dimensions (Room: 360 × 360 × 50 mm; Desktop: 220 × 220 × 40 mm) so:

• Replacement HEPAs are available from Camfil, Mann+Hummel, 3M, Home Depot, and McMaster-Carr — users pick their source + price tier
• Mission partners get true pricing (not captive supply)
• WanderStore still sells WWP-branded HEPAs for users who want to support the Community Pool — but we never force-lock

D-03: AHAM CADR certification is a HARD GATE — why

The industry has normalized "up to X CADR" marketing without accreditation. We refuse to ship with "up to" language. Every unit's CADR number on the box comes from AHAM accreditation (MET Labs or Intertek). Adds $15-25k per SKU to cert cost. Worth it for trust + B2B / HAVEN / nonprofit credibility.

D-04: HVAC Monitor does NOT move air — why

The $449 HVAC Monitor is an advisory IAQ sensor + return-duct Δp probe, not an inline HEPA. We intentionally don't try to become an HVAC OEM. The product: 1. Measures IAQ at return duct (representative sample of whole-home air) 2. Measures filter loading via Δp (tells user actual filter life, not calendar) 3. Advises HA automations + the user's HVAC (fan mode, dampers, purifier) 4. Integrates with Matter-compatible HVAC controllers (Ecobee, Nest, Tado, Honeywell)

We are not certifying a whole-home air-mover. We are certifying a duct-mounted sensor. Much lower cert burden.

D-05: Battery on Monitor Pro only — why

Monitor Pro's 18650 adds $12 BOM + UN38.3 cert + safety design burden. Rationale: portable wildfire-evac air reading + power-out monitoring in climate-event-hit communities (matches HAVEN mission). Standard Monitor stays wall-powered to keep $79 nonprofit price accessible.

D-06: Identity-aware defaults — WanderAir has wildfire + survivor + child modes

• Wildfire mode: PM2.5 alert threshold drops from 35 → 12 µg/m³ (WHO 24-hr guideline); alerts escalate to geofence (tell user before ambient AQI tells them)
• Survivor-aware display: never broadcast "AIR IS BAD" in large text if identity-aware-household flag is "children present" (could cause panic in kids who hear but don't understand context); instead, quiet OLED indicator + adult's phone notification
• Pet mode: lowers threshold responses (pets live lower to the ground where heavier VOCs pool)

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Stage-by-stage sign-off

Stage	Status	Notes
0 — Feature-parity	✅	`_COMPETITIVE-AUDIT-2026-04-24.md`
1 — Intake + freeze	✅	`_MANIFEST.md` + family expanded to 4 tiers
2 — Component selection	✅	No ionizer/PECO/UV; HEPA-H13 + carbon only
2b — Configurator	✅	`CONFIGURATOR.md`
3 — Compatibility	✅	`COMPATIBILITY.md`
4 — Sourcing	✅	`SOURCING.csv`
5 — DFM/DFA/DFT	✅	`DFM-DFA-DFT.md` — Ambassador time + ozone gate + HEPA seal test
6 — Thermal/EMC	✅	`THERMAL-EMC.md`
7 — Compliance	✅	`COMPLIANCE.md` — AHAM + UL 867 + UL 507 + ETL + ES + CARB
8 — Canonical BOM + GUIDE + STLs	✅	BOMs + GUIDE + STL-OPEN-FILES/
9 — HW↔FW	✅	`HW-FW.md`
10 — Gate review + service	✅	`GATE.md` + `SERVICE-FLOW.md`

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Critical open items carried forward

#	Item	Severity	Owner	Target
1	AHAM CADR lab booking (MET Labs or Intertek Chicago) — Desktop + Room	🔴	Cert team	2027-Q3
2	UL 867 ozone chamber test booking (Intertek or UL Northbrook)	🔴	Cert team	2027-Q3
3	Sensirion SEN55 + SCD41 + SFA30 bulk pricing commitment	🟡	Sourcing	2026-Q4
4	HEPA-H13 standard-frame qualifier (3 vendors at EVT)	🟡	Sourcing + QA	2026-Q4
5	Sanyo Denki San Ace fan supply (or Nidec alt)	🟡	Sourcing	2026-Q4
6	California CARB air cleaner registration (Desktop + Room)	🟡	Cert + Legal	2027-Q3
7	Energy Star Room Air Cleaners Version 3.0 application	🟡	Cert	2027-Q4
8	HVAC Monitor duct-install safety labeling (not a fire/smoke detector — clear positioning)	🟡	Legal + GUIDE	2027-Q2
9	⚠ needs validation: Desktop CADR target of 150 — Stage 5 prototype measurement	🟡	Eng	2027-Q1 EVT
10	⚠ needs validation: Room CADR target of 320 — Stage 5 prototype measurement	🟡	Eng	2027-Q1 EVT
11	⚠ needs validation: HEPA-life algorithm accuracy (Kalman vs simple integration) — 4-week ingest test	🟡	FW	2027-Q2 DVT
12	⚠ needs validation: Δp duct-monitor sensitivity across 4" / 5" / 6" / 7" duct sizes	🟡	Eng	2027-Q2
13	Contract manufacturer PCBA + chassis injection + final assembly (Ambassador final)	🔴	Ops	2026-Q4
14	Matter-over-WiFi CSA cert (shared with WanderSense + WanderBand family)	🟡	Cert	2027-Q1
15	18650 battery cert UN38.3 + IEC 62133 (Monitor Pro + Room Purifier UPS optional)	🟡	Cert + Sourcing	2027-Q2
16	Asthma-alert threshold medical advisory review (CDC + AAFA + NIOSH)	🟡	Medical advisory	2026-Q4
17	ESPHome upstream PR for SFA30 HCHO + SDP810 Δp (if not already landed)	🟢	FW	2026-Q4