First I'd like to say that this is a great and enormously informative forum and I want to thank in advance everyone for their help.
I have a Trane heat pump system XL 16i, outdoor model# 4TWZX6036B1000AA indoor model# 4TEE3F37B1000AA (I believe this pertains to the air handler) controlled with Honeywell VisionPro IAQ (YTH94Z1C1002) thermostat. The backup is electric strips.
The system was installed in May and had worked great until the temperatures dropped recently. What happened was the system would switch to Aux Heat when the temperatures dropped to about 41F. Needless to say, when running Aux Heat, my electric usage was not acceptable (I try to monitor my meter daily, sometimes more often) it went from about 45 KW/day (while running the heat pump) to about 110 KW/day (on Aux Heat).
When I had the unit installed (in May) I was told that there's a "cut off" temperature below which the heat pump will not be able to operate (hence the need for Aux Heat) and that it was about 45F. I recall the technician configuring the thermostat and setting that temp to 45F. I asked him then if he could lower it but he refused saying that this was the best setting and if I didn't want to run Aux Heat and continue to run Heat Pump even below 45F all I had to do is set the thermostat to Heat (as opposed to Auto). I thought that it would work for me but obviously I couldn't really test it until the fall when the temperatures dropped below 45F. Well - it didn't work, i.e. even if I set the system to Heat and it was below 41F the system would switch to Aux Heat. So I gave up and just lowered the temp to prevent the system from running as much (and it being as costly when running Aux Heat).
Then on a few occasions, while walking in my neighborhood I noticed that my neighbor's heat pump was running even though the temps were around 30F (his unit is Bryant, older and less efficient model than mine). That prompted my search online to find out if there's anything that can be done with the settings on my system that would allow for the heat pump to run at lower temps than 42F. That's how I found this great site! From here I found the installer's manual to my thermostat and was able to learn about compressor lockout and Aux Heat lockout settings. I also learned about other people (much like my neighbor) running their heat pumps in temps much lower than mine was set to.
So finally yesterday I went through setup settings and modified some of them. Listed below are the items I modified and/or have questions about:
0176 - Heat Or Heat Pump Aux stages. I believe the value set by installer was 1, I set it to 2.
0350 - Heat pump compressor lockout. The value set by installer was 45F (or 40F), I changed it to 15F
0360 - Heat pump auxiliary lockout. The value set by installer was 40F (or 45F), I changed it to 25F
0401 - Number of bedrooms. The value set by installer was (default) 2, I changed it to 5 (I have 3 actual bedrooms but also an office and a media room)
0402 - Size of house. The value set by installer was (default) 10 (1000 sq. feet), I changed it to 19 (1900 sq. feet)
After making the changes I let the system run for about a day and here's what I found:
My total daily energy consumption decreased to about 60KW from over 100KW when using Aux Heat (the weather/temps outside on both days were pretty much the same). And all that while actually INCREASING the indoor temperature - now I have the thermostat set between 68F (night) and 70F (day), and previously while running on Aux Heat I had it set at 63F (night) and 66F (day). So the house is much warmer and I'm using about a half of the energy.
The system (heat pump) seems to be running a lot - I would say about 75-80% of the time with short breaks every now and then.
1. Is there a problem with any of the settings (listed above) that I modified?
2. Related to option 0176 - how do I know how many stages my unit has?
3. Is it a problem for the heat pump to run almost continuously? Will it wear out / break sooner / cause any other problems?
Any help would be greatly appreciated.
BTW - I live in the foothills outside of Seattle, WA and my daily winter temps. are normally between 25F and 45F.