For years now most heating and cooling systems have not utilized separate Auxiliary and Emergency Heat sources. Honeywell is now addressing this by combining the separate terminals for Aux & E into one single terminal labeled Aux/E. Honeywell states that this change enables select models of VisionPRO and FocusPRO to match other Honeywell products and makes installation easier. The newer thermostats will not fit older wall plates as Honeywell has added a KEY to prevent installation of the newer thermostats onto older wall plates.
In our opinion, not only will this make installation easier by eliminating the need to install a jumper between the Aux and E terminals it will also help ensure that the HVAC system works properly. This is because many installers simply FORGET to add that jumper and therefore which ever terminal is not wired becomes unavailable to the user. For example…wiring to only the Aux terminal and forgetting to jumper to the E terminal would not allow a user to use their emergency heat if needed, and vise versa. By combining the terminals into one single Aux/E terminal it does not matter. Hats off to Honeywell for making what seems to be just a small change however the impact will be huge. By our estimation over 50% of home and business systems have at least one or more installation flaw that prevent full and proper operation…Eliminating just one is pretty big.
ON AN UNRELATED SIDE NOTE:
Remember that just because your system has “always worked”, doesn’t mean that it is working properly. This is why it is so critical not to fall for the scams offered by supposedly legitimate HVAC companies offering to perform an inspection for a ludicrously low price. Many of these “legitimate” companies even maintain an A+ rating with the BBB along with high ratings with other reporting agencies. The argument would undoubtedly be that, “Hey, it’s just marketing…every company does it.”