Technically minded?

All of the technical information about the BT21 Bluetooth thermostat at your finger tips. 

Technical data

230V AC 50Hz
Maximum Load
Bluetooth 4.2
Ambient temperature
+5°C - +35°C
Protection rating
IP21 (Safe in bathrooms outside zone 2)
86 x 86 x 10mm
25mm deep back box
Included sensors
Built in ambient External NTC10K floor sensor
Also works with
NTC 2k, 12.5k, 15k, 33k sensor probes
3 years

Download the app now!

Search ‘ThermoSphere BT21‘ to download the app
BT21 – Technical 3

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Telephone: 0800 019 5899


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We close at 5pm on 24th Dec and reopen at 7.30am on 4th Jan 2022.

Orders for next day delivery will need to be placed by 4.30pm on the 23rd Dec.