I installed a ZIM and two Omnistats 9 months ago and everything worked great until recently. The 802.11 wireless was originally setup on channel 1. Two weeks ago I had a chance to use a spectrum analyzer and noticed that channel 11 had less utilization, from my close neighbor's networks, so I switch my wireless to that channel. I didn't notice it right away, but it was causing lots of interference with Zigbee. The OmniPro would show 0 for the temps and changes to the temp settings wouldn't always go through to the Omnistats. As soon as I switched the Wifi channel back to 1 everything went back to normal.
I'm not sure how the ZIM picks which ZigBee channel to use. The lower ZigBee channels 1 - 10 are in the 915 MHz and the higher 11 - 26 are 2.4 GHz and overlap wireless. It looks like it was using one of the high channels which overlap 802.11 channel 11. Lesson is if your Zigbee ZIM is having issues communicating try changing your wireless channel
I'm not sure how the ZIM picks which ZigBee channel to use. The lower ZigBee channels 1 - 10 are in the 915 MHz and the higher 11 - 26 are 2.4 GHz and overlap wireless. It looks like it was using one of the high channels which overlap 802.11 channel 11. Lesson is if your Zigbee ZIM is having issues communicating try changing your wireless channel