Herschel's battery-powered thermostats, the T-BT and T2 should give you a full heating season's operation on a fresh set of 1.5V alkaline batteries.
However, power consumption of the unit will increase and battery life will shorten if the thermostat is not in good RF contact with the receiver (T2 pairs to R2 and T-BT pairs to the Smart-R receiver). If RF contact is poor, the thermostat will spend a lot of its time (and power) trying to acquire the receiver it is paired to. In tests, we found this can be up to x4 the normal consumption of the unit. Examples of poor RF contact could be due to:
- The receiver is too far away from the thermostat or the RF signal is blocked for some reason (electronic or physical interference): for example this can happen if the R2 has been installed in a cupboard or ceiling void;
- The receiver and heater have been switched off from the mains but the thermostat has been left on.
We also advise you use good quality 1.5V alkaline batteries. Do not use rechargeables unless they are 1.5V.