How do I set the max temp?

After fitting, run cold-only, then set the shroud to 38 °C, then hot. Rotate the stop-ring until 43 °C max is achieved at the outlet.

The Gainsborough GSi 10.5 electric cartridge is TMV2 approved out of the box. For TMV3 (healthcare) fit the -HC suffix variant.

OEM or aftermarket for Gainsborough?

For TMV2/TMV3 compliance always fit genuine Gainsborough cartridges. Aftermarket voids the GSi 10.5 electric approval.

How to Replace the Thermostatic Cartridge on a Gainsborough GSi 10.5 electric (UK)

The part

Rebalance a scaling Gainsborough GSi 10.5 electric by swapping the OEM thermostatic cartridge — restores TMV2 approval and 38 °C set-point.

Isolate

Isolate hot and cold at the built-in EasyFit valves or dedicated isolators. Drop the pressure by opening the outlet fully.

Swap the thermostatic cartridge

Undo the temperature handle grub screw, remove the escutcheon and pull the cartridge with the OEM extraction tool — needle-nose pliers will crack the Gainsborough plastic housing.

Commission

Balance hot and cold to within 0.5 bar. Run the Gainsborough GSi 10.5 electric at max flow for 3 minutes.

Verify max outlet temperature stays below 46 °C per BS EN 1111 by shutting off cold and reading the outlet.

Frequently asked questions

How do I set the max temp?: After fitting, run cold-only, then set the shroud to 38 °C, then hot. Rotate the stop-ring until 43 °C max is achieved at the outlet.
TMV3 compliance?: The Gainsborough GSi 10.5 electric cartridge is TMV2 approved out of the box. For TMV3 (healthcare) fit the -HC suffix variant.
OEM or aftermarket for Gainsborough?: For TMV2/TMV3 compliance always fit genuine Gainsborough cartridges. Aftermarket voids the GSi 10.5 electric approval.

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