Oso
Expansion Relief Valve Operation
Oso water heater installed on an unvented system discharges water from the expansion relief valve (not T&P) frequently.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed or incorrectly set pressure reducing valve, Undersized or failed expansion vessel, Faulty expansion relief valve, Thermal expansion with no room to absorb
How to Fix / Troubleshooting
Safety first: Do not cap or restrict any safety discharge. Work only when the system is cool and depressurized.
- Check system pressure: Measure cold static pressure. If above specification, the pressure reducing valve may be faulty.
- Inspect expansion vessel: Verify correct pre‑charge and replace if waterlogged.
- Replace relief valve: If the valve continues to drip at normal pressures, replace the Oso expansion relief valve.
- Verify installation: Ensure all components of the Oso unvented kit are installed as per the manufacturer’s instructions.
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Repair Difficulty
Professional Required
5/5
Required Part
Oso expansion relief valve
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