Hi there,
The EcoZone Controller has 4 outlets of 450W proportional control each, and 4 temperature probe inputs. This provides up to 1800W of proportional power control. For a given outlet in heater mode, you can use any 1 of the probe inputs as the controlling probe, for any of the 4 outlets. So you could have 4 outlets 1800W power controlled by a single probe, if you like.
Thus if all 5 levels of your rack are well matched, you can use a single probe in one of the bins/levels. Each outlet can drive any number of heaters, flexwatt, etc as long as each outlet is kept under 450W.
So one unit should be able to do the 5 level rack easily, as long as the rack levels and bins are all well matched, you only need 1 of the probes. Then the spare probe inputs can be used for extra monitoring in specific levels and bins, perhaps for overtemp alarm triggering, etc. An overtemp on any one of the probes will trigger the alarm, and can optionallly shutdown the outlet power, as well as send an email alert.
You can use as many controllers as you like, each EcoZone unit is complletely independent with it's own 4 outlets, 4 sensors, LCD display and NET connectivity. Since each runs independnetly, this provides a measure of redundancy as well. No restriction on number of units in use on the same network, etc.
The IO interface built into each unit can be used for certain power fail alert applications. If you use 2 units on 2 different AC breakers, by wiring the I/O interface connection between the 2 units, a circuit breaker trip on one of the units can trigger an I/O alarm and email alert (since 2nd unit is still up). An undetected circuit breaker trip while I am away is always one of my fears, and is more common for me than whole house power fail. For this setup to work, you need to make sure your 'net connection stays up, so it should be plugged into a breaker independent of the EcoZone units, or on a UPS. There are other ways to do this power fail function with only 1 unit, but you generally need a UPS as well, to keep the unit up long enough to send the email alert. This method also works for whole house power failure. You can always contact me directly if this is of interest.
Also have a look at the website, there are detailed specifications, full users guides, and a live demo of the web interface (play around with a live unit to see the capabilities).
Hope this helps with the questions.
Regards,
Tony