Run it empty and check the temp morning afternoon and night for a few days and see what it does , it shoudnt have temp issues if its working properly more then a degree or two if you have it in a stable room. It could be malfunctioning , I got a mini eco and it had issues I sent it back once and they fixed the circut borad but it still had issues so I sent it back again and this time they replaced the circuit bored and now it seems to be running just fine . You may have to be assertive when you talk to them though and unless its brand brand new youll have to pay to ship it back , it iddnt work the first week i had it so even though I had to be very firm they did pay for ups to pick it up and send it back after it was fixed the first time , the next time I had to pay the shipping to them my self and they paid to ship it back to me. Hopefully yours isnt broken though.Brinsea Mini eco