My wife has been reading a lot on this forum, and said someone would probably be able to answer my question.  Our observation is that our heating bills have been higher than expected since installing geothermal in November 2010.  We've identified some issues with the desuperheat plumbing that our installer corrected, but energy usage is still tracking well above 1 kWh per heating degree day.  My wife swears the air supply registers have the faint but distinct smell of electric resistance heat, but we have never seen the thermostat call for 2nd stage, nor have we seen it show a flashing "+2" that would, if I understand correctly, be the thermostat showing it is calling for aux heat.

How can I verify if the aux heat is or is not running in a split, zoned, two stage heat pump system?

Setup:
WF Envision split system Model # NDZ038A1 (Three vertical 200' wells, closed loop)
WF Envision Air Handler Model # NAH036A1001R w/ 10 Kw Aux Heat
Aprilaire Model 6404 zone board w/ 2 zone dampers
2 White Rodgers 1F95-1277 thermostats

The thermostats, zone board and compressor unit in the basement appear wired correctly per the WR, Aprilaire and WF installalation manuals.  I haven't opened the air handler cabinet to verify those connections.

We have run the system with the zone board cover off and the WF compressor cabinet DIP switch SW 2-6 set to "off" to view the thermostat inputs to the control boards.

When we set the thermostat for one degree above ambient, I can see the Y1 and G LED's on the zone board illuminate, and the first LED on the WF compressor section illuminate.  This would seem to confirm the connection from the thermostat, through the zone board, through the air handler, to the compressor, is functioning correctly, at least in first stage heat.

When we set the thermostat for four or five degrees above ambient, the system does not appear to change, (Thermostat continues to show "system on," LEDs remain lit per above description on zone board and compressor section) even after everal minutes of operation.  I was expecting to see the thermostat call for 2nd stage operation at some point?  Our installer has the Aprilaire  zone board DIP switches ("# zones to stage" and "stage minutes") set for thermostat control.

as an aside, the zone board is mounted on insulated air ducting in the attic, less than 8" downstream from where the air exits the handler to go to the dampers.  The Aprilaire manual says not to do this due to potential for condensation.....is there any chance the proximity to the air handler can cause problems for the zone board (i.e EMI)...?

Our installer will be coming back out to do some further troubleshooting on what appeared to be a faulty TXV in the refrigerant loop, when in heating mode.  Could that have anything to do with not going into second stage on the compressor and/or aux heat coming on with no indication?

Thank you for your time and consideration.

Very Respectfully,
Doug



 

Posted By Kdbelvin on 07 Mar 2011 02:39 PM

We went to investigate attic air handler and found that the two "halves" of the unit were not sealed (about a 3mm gap all the way around) and that there was a significant draw of unconditioned attic air into the airhandler whenever the blower ran. In addition, the installer never sealed around the suction line, the liquid line, etc. coming into the cabinet, so there are more places for air infiltration.

I'm waiting on a call back from my installer and trying to keep my faith in them doing the right thing...but I have digital photos of the stuff they did wrong, just in case.

Thanks again,
Kim (for Doug)