Bitrate
12-11-2011, 07:32 PM
Folks,
I have a hybrid heat system that manically transitions between heat pump and furnace. The behavior has many similarities to that described in this thread (http://hvac-talk.com/vbb/showthread.php?t=979552&page=3). I guess I'm looking for some feedback on whether there is a known issue with the controller or even if there is risk to safety or equipment life expectancy. I plan to contact the installing company Monday, but since it's non-emergency they won't respond until later in the week.
When the system is just trying to maintain temperature, it will run the HP for 10-15 minutes then run Aux heat for about 5 minutes and then switch back to HP again. When recovering from a set back of even just 1*F, it will jump between HP hi, HP lo, and Aux heat(low stage only). There are no defrost modes occurring during these. At least twice the aux heat was activated when the out side temperature was above the aux heat lock-out temperature. This manic behavior has been observed when the outside temps were anywhere between 37 & 44.
The other troubling behavior is when the compressor is running at full power and the blower fan is not running. I have observed this twice, but suspect that it has occurred many times. The times that I have seen it is when the system is heating and the outside temperature rises from from below the HP lock-out temp to above it. At this transition, the furnace will stop and the heat pump will start (high stage only). The blower fan is set to AUTO mode and will never turn on. The controller will abandon the heat pump and will switch back to furnace after about 25-30 minutes. As it switches back to the furnace, the fan starts up again. Once when the HP was active, I manually turned the fan on (AUTO to MED) and it all seemed to work fine. As soon as I switch back to AUTO (while the HP was active) the fan stopped. When the blower fan was not working, the HP was making an awful groaning noise: sound level and pitch would slowly rise then slowly fall at about 6-7 seconds. The refrigerant lines going into the heat exchange coil were very hot; I couldn't keep my finger on it.
System details are 58MVC100-20, 25HNA648 with Infinity HW rev B, SW vers. 16. Settings are: HP lock-out=35F, Furnace lock-out=40, FAN=auto, Furnace disabled for defrost mode. Pretty much everything else is default.
Does any of this sound like something you've seen before?
I have a hybrid heat system that manically transitions between heat pump and furnace. The behavior has many similarities to that described in this thread (http://hvac-talk.com/vbb/showthread.php?t=979552&page=3). I guess I'm looking for some feedback on whether there is a known issue with the controller or even if there is risk to safety or equipment life expectancy. I plan to contact the installing company Monday, but since it's non-emergency they won't respond until later in the week.
When the system is just trying to maintain temperature, it will run the HP for 10-15 minutes then run Aux heat for about 5 minutes and then switch back to HP again. When recovering from a set back of even just 1*F, it will jump between HP hi, HP lo, and Aux heat(low stage only). There are no defrost modes occurring during these. At least twice the aux heat was activated when the out side temperature was above the aux heat lock-out temperature. This manic behavior has been observed when the outside temps were anywhere between 37 & 44.
The other troubling behavior is when the compressor is running at full power and the blower fan is not running. I have observed this twice, but suspect that it has occurred many times. The times that I have seen it is when the system is heating and the outside temperature rises from from below the HP lock-out temp to above it. At this transition, the furnace will stop and the heat pump will start (high stage only). The blower fan is set to AUTO mode and will never turn on. The controller will abandon the heat pump and will switch back to furnace after about 25-30 minutes. As it switches back to the furnace, the fan starts up again. Once when the HP was active, I manually turned the fan on (AUTO to MED) and it all seemed to work fine. As soon as I switch back to AUTO (while the HP was active) the fan stopped. When the blower fan was not working, the HP was making an awful groaning noise: sound level and pitch would slowly rise then slowly fall at about 6-7 seconds. The refrigerant lines going into the heat exchange coil were very hot; I couldn't keep my finger on it.
System details are 58MVC100-20, 25HNA648 with Infinity HW rev B, SW vers. 16. Settings are: HP lock-out=35F, Furnace lock-out=40, FAN=auto, Furnace disabled for defrost mode. Pretty much everything else is default.
Does any of this sound like something you've seen before?