The overheat switch sits directly on the HD70E's heat exchanger, monitoring temperature and cutting the gas supply the moment it runs too hot — preventing heat exchanger damage and runaway overheating before either becomes a real problem. It's a bi-metal switch, so it will usually reset itself once temperature drops back down, but if the underlying cause hasn't been addressed, it will trip again the next time conditions push temperature out of range.
That cycling behaviour is worth reading correctly: the switch doing its job is also a clear signal that something upstream needs investigating. Common causes include restricted water flow, a scaled or partially blocked heat exchanger, airflow problems at ignition, or incorrect gas pressure. Replacing the switch without identifying and fixing the actual cause isn't a repair — it just delays the next trip.
The P70EV-713 is the genuine Rinnai overheat switch made specifically for the HD70E (REU-VRM3237), restoring heat exchanger protection to factory specification.
⚠ Important: A repeatedly tripping switch indicates an underlying fault. A Gas Safe registered engineer should identify and resolve the root cause before or alongside fitting a replacement switch.
A tripping overheat switch is a safety device doing exactly what it's meant to — but it's only half the job to replace it. Trace the cause first, whether that's restricted flow, a scaled heat exchanger, or an airflow or gas pressure issue, then fit the genuine switch and the protection is restored properly rather than left to trip again on the next high-demand cycle.
Order the Rinnai P70EV-713 HD70E Overheat Switch online today.
| Manufacturer | Rinnai |
|---|---|
| Part Number | P70EV-713 |
| Product Type | Overheat Switch (OHS) – Bi-Metal Safety Switch |
| Compatible Model | Rinnai HD70E (REU-VRM3237) |
| Mounting Location | Heat Exchanger |
| Function | Cuts Gas Supply if Heat Exchanger Temperature Exceeds Safe Limit |
| Switch Type | Bi-Metal Auto-Reset Safety Switch |
| Appliance Type | Continuous Flow Gas Water Heater |
| Installation | Gas Safe Registered Engineer Required |
