3 ton Waterfurnace, 1 year old, 300 foot well fed open loop, 4.5 gpm. 2700 SqFt 2 story, slab. Honeywell TH6320R1004 FocusPro Thermostat. System runs almost constantly for heat and is keeping up fine in Stage 1. 30 Deg F outside. Setpoint is 69. All of the sudden, it calls for aux heat. Thermostat is at setpoint at 69. I am using all of the Honeywell default settings for a geo heat pump. What gives?
Your thermostat is not super sophisticated and likely calls for auxiliary after a certain time period.....or if you have a single stage heat pump with aux as second stage you may need a little shot in the arm if your unit is running nearly all the time. If cost calcs from installer included a bin report you can compare projected cycle% of the hour to actual and see if they jive. If not possibilities include lower than projected EWT (which may be remedied by uping the flow some), lower than designed GPM or thermostat activation of aux after a prescribed period of time. Other possibilities are numerous. Other fixes might include an outdoor temp monitor that locks out aux above balance point. J
Thank you for the reply. Short history, this system replaced a 25 year old Geo system last January. It is a WF Envision 038 and the Honeywell Focus Pro does read outdoor temp and humidity. Aux heat is after second stage. Right now I have W2/Aux disconnected. I agree that time may be the factor here as both set point and T-temp agree at 68 Deg. F. I do have a "Heat pump Auxilary lockout" adjustment that is set to 0 (zero), and means "No heat pump aux lockout". There is also a similar setting for Compressor lockout, it is set to zero also. I am not quite sure how these features work. There are temperature ranges from 5 Deg to 65 Deg in 5 degree increments to choose from. The FocusPro TH6320R-1004 manual is very poor. I can email a .pdf if you like. I understand that on cold days, it could run almost all the time. My issue it the well and well pump take an extra toll but it is what it is. Someday, may be able to change to closed loop.
Here is a link to the system installation guide: http://www.ntsupply.com/files/products/YTH6320R1015InstallGUide.pdf I am not aware of a reason to use the Compressor Lockout if you have electric auxiliary heat and no furnace. You can use the Auxiliary Lockout feature to limit electric auxiliary heat usage to times when the outdoor temperature is below your setting. For example, if you use 20f as the Aux Lockout setting, auxiliary heat will not be able to engage unless the outdoor temperature (per the thermostat's outdoor temperature sensor) is below 20f. To be safe, disable the Aux Lockout if you go away. This way, the aux heat can engage if you have a system lockout, and keep the house from freezing. As a starting point, you can try setting the Aux Lockout 5-10f above the system design temperature (aka balance point) per the paperwork you received from your WF dealer. Other ways of reducing aux heat usage with this thermostat is to maintain a constant thermostat set point, or if you must set back for comfort (like us) keep the setback to 2f. You can use a greater setback if the outdoor temperature is above your Aux Lockout setting (so aux heat doesn't engage), but recovery times may be long. You can also use Adaptive Intelligent Recovery with programmed temperatures that you set in advance. Manual changes, even as low as 1 degree can bring on higher stages quickly - so avoid making manual adjustments whenever possible. It doesn't appear that this thermostat has an option for "less aggressive" heating that many of us like, but this may not be a deal breaker with the other opportunities you have to manage aux heat usage. Make sure you involve your installer with proposed changes.
Thank you everyone for the excellent replies. I have basically come to the conclusion that it is just plain cold here in Central CT now. Most likely, Aux heat is being called for correctly. I have made two changes to the WF Envison settings. The first is SW3-2 ON, so it finishes a cycle in second stage. This was recommended by a WF tech last week. (At least for the cold winter months) Next I increased high speed blower, SW2-9 for 1500 CFM. I will monitor these changes for unusual cycling. I am going to follow GEOME'S advise regarding low setback and Adaptive Tuning, by maintaining 69f from 3:15 to 10PM, and from 10PM to 3:15PM, 68f. I wasn't aware that Adaptive Tuning only works with programmed schedules. As for the well, like I said, we have never run out of water and 4.5-5 GPM is not that bad on the pump. Thank you all and Happy New Year.
