I recently bought a home with a Honeywell Chromotherm III (T8600D)
model thermostat. My home has a natural gas burning furnace and an a/
c system, both operating off of a single transformer.
I am going to replace the thermostat myself and am considering either
the Honeywell RTH8500 or the TH8110. The RTH8500 is the "retail"
version of the thermostat and the TH8110 is the "professional
The main differences I see between the two are:
1. The retail version runs exclusively off of batteries. The pro
version also takes batteries but can optionally run off of the 24vac
2. The pro version has a lot of installer options.
I read through all the different installer options for the pro and it
appears to me that given my setup I will be leaving them at the
factory default settings.
Also, I don't today have a wire coming from the common side of the
transformer into the existing thermostat, so I don't think I'll be
able to take advantage of
the 24vac option to power the TH8110.
So if I am going to rely on batteries either way, and if I have no
reason to change the factory defaults, is there any reason to get the
TH8110 instead of the RTH8500?
Do the "pro" versions of the thermostat have any other advantages over
the comparable retail model (like quality of construction or