This is my first entry in this forum and would like to first say how much I have learned from all of you regarding Geothermal systems.  Secondly, I apologize for any inconsistencies or incorrect statements, being new at this.

   We are located in southern WV and it is presently 12° F since we are experiencing a cold snap. We have just moved into our new home, approx. 9600 sq ft of conditioned space. We have installed a Waterfurnace Envision series system, calculated 20 ton capacity with 20 wells dug 150' each.  The system is made up of 2 Envision "all-in-one" units for the basement and 3 Envision "split" units (2 for the main floor and 1 for the upstairs) for the remainder of the home.

   I have noticed since we have moved in, that the units in the basement (no windows and below grade) hardly ever run and maintain a constant 67-68° F.  However, the upstairs "split unit" runs almost all of the time but can reach/maintain the desired temp which is presently set at 66 F (right now running on Auxiliary).

   Of the two main floor "split units", the one I am concerned about is the unit that supplies the master bedroom-bathroom, fitness, study and great room.  This part of the home has a substantial number of large windows ( we have NO window coverings presently) and I guess you could say it is the most "exposed" since it has a NW/SW location.
   This unit does not seem to be able to achieve the desired temperature setting.  For instance, T-stat setting of 70° F it reaches a temp of 65-66° F on Auxiliary.  It is constantly running  but never hits 70°.  Interestingly, on our more typical 40-45° F days, the desired temp can be achieved. I even turned the thermostat to EM heat and it didn't go above 66.

Is this phenomenon a problem with that particular unit or is it a function of the fact that we have a large surface area of windows that are exposed and uncovered?
Sorry for being wordy but I appreciate any ideas.

20 tons sounds like enough for 9600 sq ft. I could be a insulation or a geo problem. But one thing for sure it is a problem.

My guess is this has most to do with the unusually cold weather you are having. All of the uncovered windows don't help, but they should have been factored into the design.

It sounds like a reasonable load for the home , but inadequate distribution of the load , time to move some ducts

Lots of questions occur regarding load and distribution. But I'd start by making sure all breakers are turned on for aux coils and no air noise at flow centers.
Good luck,
Joe

In a multi unit system such as yours determining if the units are seeing the correct flow from the circulators is another place to check for good operation.
Eric

20 Tons total for 3 units? What is the break down in tons for each unit? 20 Tons sounds like enough, but I'm wondering how they are distrubuted. I would guess two 6 ton units for the downstatirs and one 8 ton for the upstairs. 

As for the system not being able to achive the desired temperature on emergency heat, if would of course depend on how many KW you Emergency Heat heating element is. It sounds like it's too small for the load required to me.
 

 

thanks for the input. a few more things have come up. We looked at the split unit supplying the master bedroom area and the panel showed 3 flashing red lights which according to the owners manual indicates that the normally open pressure switch valve failed to close. Additionally, the small window to view the furnace flame showed no flame.

to TechGromit, I may not have been clear about the number of units. We have two units in the basement, two split units for the main floor and one split unit for the upstairs. (total 5 units)

What kind of flame are you looking for?

I thought you had geothermal heat pumps installed?

Three, Five, 19, doesn't make a difference, what is the tonage breakdown of each, and how much for each level? I'm now guessing 4 units for the down stairs at 3 1/2  tons each and 1 unit for the upstairs at 6 tons. Seems strange that you have two complete units in the basement and two more that are splits in the basement, my only guess would be that the basement doesn't extend to all parts of the house and those parts of the house that doesn't have a basement is on a slab, no way to run ducts under there from the basement.
  

I see what you're saying. I will get that info to you.

First, can you email me again so we can talk?  The email came from greenbuildingtalk and I didn't know how to get back to you.  Secondly, I'm in Fayetteville, and we haven't been near 12 degrees today!!!  My house is only 1600 so we only have 1 unit...but it was installed during the last really cold snap we had that week in November, don't know when you moved in, but, you're right, I think we have been dealing with the same dealer.  THat being said, I have definitely  noticed that when it is this frigid out, the unit has to work harder, ie...it runs longer and more often, but even then it still doesn't run non-stop.  It did initially, stopping only 2-3 minutes an hour, but that was in the first 2 days or so and it was still really cold.  This forum has been awesome for answering questions, and I think it was here that someone said that with temp extremes like this, even the geothermal has to work a little harder (do people agree with that?)  We have been able to achieve all our temp settings without ever using auxiliary heat, but we have to go 1 degree at a time.  I was told it is better to pick one temp and stick with it b/c it's more work on the system to change back and forth.  On a normal day, we bump it up to 68-69 and down to 64 at night.  Our living room is usually 5 degrees cooler than the rest of the house, but it has a sunken floor and vaulted ceilings, one air intake and one small 6 inch register out...we've talked and I think we are going to add a second out register.  I was told it would take awhile for the ground loops to get up to temp, considering when we did the digging (we did 3- 80 foot trenches with loops, 5 feet down)  it was in the teens, the dirt covering was exposed, the loops were exposed to the cold.  What does everyone else think?

By the way, I can tell you who in the area NOT to use!

Macalata,

I installed a 4 ton vertical system yesterday in Dover, DE. High temp for the day was 20 degrees. After the fusion and inside work the loop tales had frozen. No way to purge the system. We pressure tested with air on the supply and return, backfilled three feet of cover and left. We returned this morning and the temp was 17 degrees. We hooked up the purge cart and all was good.
I do not think that the temp when system was installed is a factor. The ground is a lot warmer than we think.
Eric

Assuming the pipes didn't freeze so hard as to spring leaks, all will be well once they are buried several feet underground.

If you get through this cold snap without using aux heat, you are way way ahead of many others