I used to have one of the Honeywell programmable thermostats from ~20 years ago, and it was still the best I have seen or used. The UI was nothing special, but the feature set (eg ability to program blower-only periods to mix the air without having the blower running all the time, PROPER support for 2-stage furnace) was exceptional. It used more wires between thermostat & furnace in order to communicate things like low/high heat & blower control.

The main thing I liked about it was that it learned response times & profiles for your house and used that information to properly manage the low/high heat options on a 2-stage furnace. Most houses show a temperature drop at first when the heat comes on as cold air from the periphery gets mixed with the warmer air near the center, and modern thermostats seem to interpret that as "hey it's getting colder I must need to switch the furnace to loud immediately".

These days I have a Bryant Evolution thermostat that apparently uses some kind of serial data link between furnace and thermostat. Seems to work well** but I miss the features of the Honeywell, and I seem to be stuck with timer-based 2-stage operation which can be pretty annoying (furnace switches to high with a mighty roar 30 seconds before thermostat decides that temperature has reached the set point and shuts it off) - the only real solution I found was to set the timer for long enough that high heat was never used except for the occasional bitterly cold day when low heat was not able to keep up.

The problem is that it's really hard to get a straight answer on feature set with modern thermostats - lots of info on how colourful the GUI is, lots of info on how the thermostat will revolutionize your lifestyle, but hardly anything on what it actually does frown

** actually it doesn't work all that well - furnace shuts down occasionally with a "configuration" error code, apparently caused by a firmware mismatch between thermostat and furnace boards... I'm going to get one or both ends updated next time the furnace guy comes around and see if that helps - it's not good if your furnace shuts down randomly in the middle of winter when you are away for a few days

Last edited by bridgman; 03/25/18 08:26 PM.

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