I hooked up a APC RS1000 to my Harman Accentra, this unit is 1000 VA and 600 watts. I put my stove in test mode, which all blowers and auger are activated. I then unplugged the battery backup and the electronic still were working but all the motors slowed down and started to hum. Wow, Tried this again with my other battery backup and same result. Looked on the internet and it seems that any battery backup that is modified sine wave is fine for electronics but will not work well for fans and motors. I also went to work and try this with a fan on one of our battery backups and same result. So I guess that I am now looking for a battery backup with a pure sine wave. Any suggestions?