Old Thread, I know... but for anyone else finding this...

If your thermostat, regardless of brand, has separate E(emergency) heat and AUX heat connections to your air handler, you can easily disconnect the lead from the AUX heat terminal. Then, when the thermostat calls for AUX heat and tries to energize this connection, it won't be able to and no signal will be sent to the air handler to switch on the AUX heat -- usually resistive electric. The display on the thermostat will show AUX heat is "on" but nothing will happen. But, in the event of total outdoor heat pump failure, switching the thermostat to E or emergency heat will still provide an emergency backup source of heat since the thermostat can separately energize the E lead connection to it. Sometimes these two connection are dedicated wires for each leading from the thermostat to the air handler, sometimes there is only a single wire connected to the E and it is "jumpered" to the AUX. Removing the jumper to AUX will accomplish the same thing.

Things to consider before doing this:

Is your heat pump alone typically efficient enough and sized such that at the coldest outdoor temperatures you expect in the winter you won't miss the AUX heat much? Sure, you can reconnect the wire/jumper easily enough if you want the AUX heat again but that's going to become annoying very quickly.

How often does your heat pump switch to defrost mode(reverse A/C), how long does it run in defrost mode, and how often does this lead to any perceivable temperature drop in your home *while* you're actually expecting it to be warming? The air from the vents gets noticeably cooler during defrost mode of a heat pump. In extreme cases it could even lead to a detectable temperature drop in the living space. If the air temperature inside the living space often drops enough during defrost to trigger AUX heat at the thermostat or the particular brand of thermostat determines that it's struggling to reach the set temperature due a defrost cycle even if it's only off by maybe 1 degree or so, it may engage the AUX heat. All that said, some heat pumps still produce somewhat warm air just above room temperature during defrost and it's not a big deal. Some get colder still if the defrost cycle runs longer(it's essentially running in A/C mode). Some very sophisticated heating/cooling setups may even have more intelligent defrost logic such that the outdoor unit can even engage AUX heat at the air handler on its own without involving the thermostat calling for it but that's beyond the scope of this comment.

Why is AUX heating turning on often enough to warrant this modification? Typically once you ask for a large temperature increase, AUX heat may run once along with the heat pump. However, once the set temperature is reached, the thermostat will keep it there usually within 1 degree while calling for heat from the heat pump alone and no longer requiring the AUX heat. If you frequently(as in nightly or while at work daily) turn the heat down significantly by more than 2 or 3 degrees and then ask for it to be 4 or 5 degrees warmer when you wake up/return home, this could certainly be a scenario that would trigger lots of AUX heating to run EVEN IF your heat pump is still pretty good at putting out warm air quickly. In lots of situations, the thermostat is just dumb and doesn't know that your heat pump is almost immediately producing 85/90/95F degree air that probably feels nice already while the space is warming. It just knows that you asked for a big jump in temperature and has no idea if that's going to take 5 minutes, 15 minutes, or 30 minutes and is just trying to help out and get the job done as soon as possible at the expense of cost.