Our 3rd heating season with a WF ND049 unit in a 3100sq ft 1981 vintage home.  First couple of years I tried to run the unit like our fossil furnace with 5+ degree setbacks and fan running only during on call.  Winter design temp was -12F.

This year I've simply set the thermostat to a comfortable temp during occupied hours (70) and setback only 2 degrees to 68 at night.  I've also let the ECM fan run 24x7 since we have an Aprilaire 5000 air cleaner.  Previous heating seasons I noted the indicator would show on the Honeywell VisionPro thermostat we would be operating on emergency heat during cold snaps.  I don't have an easy way to measure loop temps right now but noted a bit less frost on the brass connections.

Result is a much more consistently comfortable environment with no dead spots, cleaner air and less $$$?  Had the WF tech do a seasonal maintenance on it last year.  He may have "tweaked" the setpoints but, as of now I have absolutely no regrets about making this investment.  I'm doing a full window replacement project starting February (depending on temperature).

I also work in a large 30 year old government building.  They are doing a total geo retrofit and will have nearly 200 wells.  Digging starts this summer.



EDIT:  So very next day it's 2 above and the unit is on AUX heat.  Perhaps I just caught it at a different stage yesterday?

Brrrrr.
Keep that aux coil handy in case it gets cold there
Our design points are above zero. at -17 we would be nearly at system capacity with auxiliary rockin'.
Joe

PipeMajor, dont get to overly hung up on Aux heat running. The unit is designed to use Aux heat. its cheaper to burn a little aux heat then to oversize the equipment and increase your upfront capital costs by thousands just to be sure it doesnt use $10 of Aux heat on an extra cold day.

when he says he tweaked the set point my guess would be he turned off the intelligent recovery on the stat. Im not a pro with those t'stats but have heard some negative feedback from people using them on geo.

The fact your leaving the stat alone and letting the geo do its thing is smart... it will run more efficiently that way.

Posted By MichaelR on 04 Feb 2011 03:37 PM
when he says he tweaked the set point my guess would be he turned off the intelligent recovery on the stat. Im not a pro with those t'stats but have heard some negative feedback from people using them on geo.

I have helped several people on this forum "tweak" their VisionPro 8000 series.  I use the terms "tweak" and "set correctly for comfort and system operation" interchangeably.  "Tweak" is much shorter, so I prefer to use that word.

I havn't heard (in geothermal forums) of any professional model Honeywell thermostat not working well with a geothermal system after being tweaked (turning the intelligent recovery on, setting the heat mode to less aggressive, and setting the CPH to 2 or 1, and not setting back more than 2f if at all.)  I have actually heard positive things about the thermostat afterword.

Not that I love Honeywell.  Their customer service and some thermostat owner's manuals are severely lacking, but their thermostats work great with our systems (after, well you know, being tweaked.) 

I can only second that. We use them on almost all of four systems, no regrets. It is not that the others are not good, but here we have some which work great, and we simply do not want to change a winning team.

May be a degree of setback is fine, but geo is about setting it and forgetting it.....