Make sure and get the new one 7028/3- much better design. It has a hard wired 2M cable. I would worry extending the cable could affect the readings. The new unit can switch far more power up to 1800w on the 230V version- 900W on the 115V version. It is easier to switch from heat to cool as the jumper is in the battery case so you don't have to open it. Also the design was changed from digital to analog. While the may seem a step backword analog is far more relaible as we found digital devices accepted interference from the magnetic fields of fans/chillers/heaters and this could reset the microprocessor, the analog system is completely resistant to this.