Adrian Bretsch
ba6622bed7
All Markdown documentation files for the ThermIQ smart hybrid heating system. PDFs excluded via .gitignore — generated on demand. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
88 lines
3.6 KiB
Markdown
88 lines
3.6 KiB
Markdown
# ThermIQ — Safety Architecture
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## Non-Negotiable Constraints
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These constraints are architectural. They must NEVER be relaxed:
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1. **Miners must always be hard-disconnectable via contactors** — K10 (Miner 1) and K11 (Miner 2) are power contactors. Software can only energize/de-energize them if the safety relay allows it. The safety relay acts first.
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2. **Safety logic must never rely on software or network** — The dual-channel safety relay operates entirely in hardware. If all of: RevPi, Node-RED, Home Assistant, MQTT go offline — the safety relay still functions.
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3. **EVU input of Buderus is dry contact only** — Relay K7 is potential-free. It MUST NOT inject any voltage into the Buderus WLW186i EVU input I1. Only open/close the contact.
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4. **No WiFi for critical energy components** — All control runs over wired Ethernet.
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5. **Cloud never required for operation** — Cloud APIs are optional and read-only. The system must operate indefinitely without internet.
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6. **If RevPi crashes → miners must shut down** — The safety relay is wired so that loss of RevPi heartbeat de-energizes contactor coils.
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## Safety Circuit (Hardware)
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```
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[E-Stop 1 — NC] ──┐
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[E-Stop 2 — NC] ──┤
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[FLOW OK — NC] ──┤──→ Dual-channel Safety Relay (with feedback loop)
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[TEMP MAX — NC] ──┤ │
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[Reset — NO] ──┘ ┌────┴────────────────┐
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↓ ↓
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[K10 coil] [K11 coil]
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(Miner 1) (Miner 2)
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↓
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[RevPi DI — Safety OK feedback]
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```
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**Dual-channel safety relay with Rückführkreis (feedback loop)**:
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- Both channels must be healthy
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- Feedback contacts of K10/K11 are wired back into the relay
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- Manual reset required after trip
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- Safety OK signal fed back to RevPi DI for software awareness
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## Safety Input Signals
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| Signal | Type | Condition | Action on Fault |
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|--------|------|-----------|-----------------|
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| E-Stop 1 | NC | Opened = pressed | Miners off |
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| E-Stop 2 | NC | Opened = pressed | Miners off |
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| FLOW OK | NC | Opened = no flow | Miners off |
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| TEMP MAX | NC | Opened = over-temp | Miners off |
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| Reset | NO | Momentary close = reset | Re-enables safety |
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## Contactor Logic
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```
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Power path: AC bus → LS breaker → K10/K11 contactor → Miner plugs
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K10/K11 coil: ONLY energized when safety relay output is OK
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K10/K11 Hilfskontakt: feedback → RevPi DI (software monitoring only)
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```
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Both Schuko plugs of each miner must be routed through the respective contactor.
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## Heat Pump EVU Logic
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```
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RevPi DO_EVU_SPERRE → K7 relay (potential-free) → Buderus I1
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K7 closed = EVU Sperre active = heat pump blocked
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K7 open = EVU Sperre inactive = heat pump free to run
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```
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Logic: When Pufferspeicher is hot enough, block the heat pump to save energy.
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Default state (RevPi off): K7 open → heat pump autonomous.
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## Fault States and Recovery
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| Fault | Detection | Recovery |
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|-------|-----------|----------|
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| Safety trip | Safety relay drops + RevPi DI goes low | Fix cause, manual reset button |
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| Flow loss | FLOW OK contact opens | Restore flow, reset |
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| Over-temperature | TEMP MAX contact opens | Cool system, reset |
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| E-Stop | NC contact opens | Release E-Stop, reset |
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| RevPi crash | Safety relay heartbeat lost (if wired) | RevPi reboot, system re-initializes |
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## Wiring Notes
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- Safety circuit wiring: use screened cable where possible
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- NC contacts preferred for fail-safe behavior (open = fault)
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- Contactor feedback contacts must be wired for complete Rückführkreis
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- 24 V DC safety circuit — do not mix with 230 V circuits
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