I wondered how much temps fluctuate in a viv - is it OK/normal for them to fluctuate within a few degrees throughout the day? I have new CHE and new thermostat (which I thought might be faulty as the temps seemed to be fluctuating between 85 and 100 at the hot end last night). So I swapped it for my daughter's relatively new dimming thermostat this morning at 7 and it held exact temps all day - until about 7 this evening - when it had dropped a degree, then it dropped another degree, only to go up again about 15 mins later. Now it has dropped another degree again.

The viv (it's a new set-up) is positioned on my long dressing table and the hot end (where the CHE is) is under a window - would the open window cause the fluctation - though I would have thought the thermostat would compensate for this. One of the ventilation holes is also right behind the CHE - is this what could be causing it or is the fluctation throughout the day of just a few degrees acceptable? It's a 4 ft long viv so there's plenty of room for thermoregulation.

And one more thing - I'm not used to dimming thermostats (it belonged to my daughter on a viv she had) but not only does the mains light stay on, but also the other light (which goes off on a normal stat).