HCS II-HVAC: Integration details

When I started looking for a thermostat that could easily be interfaced with my HCS II home automation system, I had several design goals:
 

• It had to be autonomous in the case of a home automation system failure
• Can take temperature setback levels
• Temperature regulation should be within 0.5 degrees Celcius
• Could control forced-air heating system with centralized air conditionning
• It had to be available for less that $75

My first thought was to make my own thermostat with multi-zone capabilities but the performance of the oil-fed furnace installed in the house I just moved into is well balanced and decided that zonning was not a necessity.

I then looked around on the Internet for a commercially made thermostat that met my design goals and most I found were high-priced.  I then found a company in my backyard that manufactured just what I needed.
 

Detailed implementation:

Figure 1 shows what the Aube TH123 thermostat looks like with it`s cover installed.  On it you will find an LCD display, temperature level controls, automatic or manual selectors.

Figure 2 shows what controls are available when you slide the cover open.  Slide switches permit you to control the fan operation and select between heating and cooling mode.  Pushbuttons will allow you to enter the programming mode and modify the settings as well as check and reset the filter maintenance timer.

In Figure 3, you will notice that when you take the cover off, you have access to the two "AA" size backup batteries.  Taking the terminal strip cover off shows the different connctions available to the HVAC system as well as the ones for the home automation system.