WanderAir Family — Decision Log
Running log of every keep/swap/drop decision. Citations per entry.
---
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 (WV-AIR-MON-STD): IAQ sensor only, replaces Awair Element 2. Desktop Purifier HEPA-H13 (WV-AIR-DESK), 150 CADR bedside/desk unit 3. Room Purifier (WV-AIR-ROOM), 320 CADR large-room unit 4. Whole-Home HVAC Pre-Filter Monitor (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 (estimate): 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 Sensor Pod 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
---
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 the 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)
---
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` |
---
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 Sensor Pod + 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 |