Another HVAC guy question: thermostat programing for heat pump vs. heat strip temp

rjacobs said:

I know we have a few HVAC guys on here. I posted this on another forum and didnt get much traction except "yea probably should change that setting"...

Weve been in our house for 4 years now and every winter our electric bill is higher than in the summer... We live in Texas, our summers are brutal our winters, overall, are mild. I always questioned it.

In the winter we run the house during the day at 66 and at night let it cool down to 60. We have a heat pump system with heat strips backup. I read something recently that if you let your temp difference get to great that your heat strip backup will kick in and can cause really high electricity usage... The air coming out of our vents when the heat comes on is hot and thus I figured our heat strips are coming on due to a 6 degree temp difference... I dont remember that to be the case in my old house that had "emergency heat" on a switch which activated the heat strips if it got to cold outside. I also dont remember that in the house I grew up in that had heat pump heat with "emergency heat" strips on a switch. Both the air was normally "cool" unless you activated the heat strips.

Im FINALLY looking at this so I went into the advanced menu in the Honeywell T6 Pro thermostats and see that code 340 "backup heat droop" is set to zero. This to me, according to how I read the manual, means that my heat is 100% coming from my heat strips and I am never letting my heat pump do anything basically. I checked code 205 "heating equipment type" and its set to 7 for "air to air heat pump".

So I am thinking I need to set my "backup heat droop" number to something other than 0 in order to let my heat pump actually work without having my heat strips kick in... Is there something scientific to picking this number?

I think I would be ok with bumping up my night temp if it means keeping my heat strips off and relying on the heat pump(which is what we SHOULD be doing)...

Was thinking of setting this number at 4 and then setting my night time temp at 63 which should keep me inside of the 4 degree window where the heat strips would kick on.

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rjacobs said:

Thanks much.

each number, according to the book is 1 degree of "droop" and looks like you can do up to 15 degrees with 0 being marked as "comfort"... So I assume that means if the requested temp is more than x degree's higher than what its at, it will kick on the "backup heat" as Honeywell calls it until its within the temp range and then kill it and you are back to heat pump. 0 is obviously way to sensitive as, from what I can gather, it goes to "backup heat" immediately and never gives the heat pump a chance to work.

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rjacobs said:

Chatted with @DarnYankeeUSMC for a few, he had me check a few things, explained how the thermostat is "supposed" to work and suggested some settings to keep my electric heat from kicking on instantly.

Thanks again for chatting with me.

It'll be a few months until I can see if these changes worked and lower my electric usage.

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tadawson said:

It kind of depends on the 'stat. I had a heatpump/electrix aux in TX aswell, and on my high end Honeywell stat, if running a schedule, it calculated the start time needed to reach the target onschedule without the electric, and did that. If you just went to the 'stat and cranked it up, then the differential applied, and it went balls-out to hit target RFN.

It's as much about programming as well as how you use it.

Mine also had the ability to program lockouts, such as don't run the pump below a certain outdoor temp, or don't run the aux above a certain outdoor temp, and the latter would likely do what you want, only allowing the aux when it was cold enough to compromise the heatpump output. (Of course, you need an external temp sensor for this to work, and a stat that supports it).

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