How to Replace a Bristan Opac Cartridge (UK)
Fit a genuine OP-CART cartridge in a Bristan Opac. UK isolation, service pattern and cold flush.
Bristan
Identify
The Bristan Opac uses the OP-CART cartridge. Confirm from the label under the temperature knob before ordering.
Isolate
Turn off hot and cold supplies — usually 15 mm service valves either side of the valve, or the local isolators under the floor. Open the valve to drop pressure.
Fit
Remove the temperature knob (grub screw at 4 o'clock on most Bristan valves). Undo the retaining nut, withdraw the old cartridge. Grease O-rings with silicone grease, fit new cartridge, torque nut to 12 Nm.
Commission
Flush cold-only for 30 s to clear any grease. Set stop position — on TMV2 units, set to 41 °C at maximum.
Frequently asked questions
- OEM or compatible?
- Bristan thermostatic cartridges must be OEM to preserve the TMV2 approval on hotels, care homes and schools.
- How often to replace?
- Hard water: every 2–3 years. Soft water: 5+ years.
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