I was fortunate to have a separate 200A service brought into my home, where I only have my new Geothermal Heat pumps connected (completely - compressors, fans, heat strips).
PPL electric in Pa provides some limited charting for usage across a month. I've attached an image of our 11/19 to present chart of energy usage on that separate service vs. temperature outdoors.

We installed: 1 - 5-ton Climatemaster packaged unit (2-pumps for loop) and 15kw heat strips.
                   1 - 2-ton Climatemaster split unit (1 pump for looP) and 10kw heat strip)
                   1 - 2-ton Climatemaster split unit (1 pump for looP) and 10kw heat strip)

Our climatemaster design run has the 2 2-ton units not ever needing AUX for our location (eastern Pa.. i think they used Harrisburg as the comparison location), and our 5-ton might need aux at around 15F.

They have been running what seems to be pretty well ( I need to check this month's EWT, but I was around 45-48 at the 11/19 timeframe. I think that we have not been anywhere close to using AUX as the loops were larger than design, and the three systems cycle nicely about 10-15 min on and upwards of 15-20 off, with on-times a little longer at night when Outside Air is around mid 20s, but still around 3 CPH.

The first question is: Am I correct to assume that if the systems are generally cycling like above, Aux is likely not even coming on? Wouldn't they run full time for quite a while before 2nd stage needs the aux assistance? That would probably be obvious when listening?

The second question is, does this usage look right for the systems installed in total? around 100kwh per day that is avg temp in 20s...? And significantly lower when the temp seems above 30?
Is this an indication that even though I do not see the AUX on (the honeywell Vision Pro doesnt have a nice light to come on when Aux is running!) it might be running on one or more of them when we are in the 20s outside?

Having said all this. We were on HP/Oil originally. Since installing these things, our electric bill is looking way, way, way better than the combined electric /oil when we used dual fuel with a 40F cutover! I think we are on track to save almost 250gal / month of oil min.... and the electric increase to be totally on geo is minimal as compared to our overall electric use! (many computers/servers, appliances). So. I know its a success, but just wondered, since I now see the Geothermal costs completely on one electric bill, if this usage is ballpark to what others would see for similar units...

thanks in advance
Dan Z

Sorry, I forgot to add: in Pa PPL terms, this comes out to about $180 for the period in the chart above.....for a month of the three systems fully running.

Here are some numbers for you to compare to, for similar equipment (2-stage, closed vertical loop, variable speed blowers), for a 3400 sf home:

For 327 Heating Degree Days so far this month (Dallas climate):

I have extracted 3089 KBTU from the ground, averaging 164 KBTU/day.  Normalized to HDD, this is 9.4 KBTU/HDD

I have consumed 420 KWH, averaging 22 KWH/day.  Normalized to HDD, this is 1.3 KWH/HDD.

You can further divide by KSF to normalize for house KSF differences.

Best regards,

Bill

OK, I'm going to take a crack at comparing.... please stop me if the logic is wrong...

Our place is approx 5300sqft covered by the above systems.
So, I first normalized the KSF numbers....as compared to you above.
(5300/3400sqft = 1.56)

You came up with 1.3 KWH/HDD, so if our energy use were nearly identical / on-par, I should come up somewhere around (1.3 * 1.56 = 2.03kwh/hdd) based upon my totals from PPL and the HDD info.

For the HDD data, the closest I could find was Allentown, Pa (ABE) and the month to date Heating Degree Days = 559.

Between 12/1 and 12/18 I used approximately 1085 KWH.  So, this averaged 1085/18 = 60.2 KWH/Day.

Applying against HDDs, 1085 KWH / 559 HDD = 1.94 KWH/HDD.

Based upon this rather loose calculation / comparison, it looks fairly close to the predicted 2.03 kwh/hdd. My numbers can be slightly off due to rounding the sqft, and estimating data gaps from the Energy provider data (it was missing two or three days data, so I interpolated) or even the difference between Allentown and Quakertown PA (approx 25 miles).

So Bill,  this exercise, with the assumption that your system is on-par for Climatemaster, as compared to what I seem to be showing, indicates that I am ballpark on energy use.... right? Or, at least, it says that you and I are seeing similar energy consumption when other factors are normalized......

Does this sound logically right?


Also: the other questions above: Is it safe to assume that if the outside temps are low (for us down in the teens/twenties), and the unit is cycling reasonably 3 times per hour, I likely am not even close to aux usage. I guess what I am asking is how to determine when I really should expect Aux to be needed. My assumption is this. The design software said that for the 5-ton unit, it would likely go on AUX strips at around 12F outside temp. I'm assuming that if correct, that means that somewhere in the teens I would see the Geo unit running pretty much full time stage1/stage 2, as an indicator that I am getting close to the need for aux. is there a formula or observation that anyone has to tell me based upon the temp buckets that the geodesigner application prints, when I should expect the system to run extremely long (ie, less cycling)? I'm assuming that if they can predict the temp at which they think AUX runs, it can also be predicted the approx temp where things start running more continuously?

I know, I'm overanalyzing and shoudl jsut be happy with the great results so far.... but IT types don't tend to do that! I want to learn the algorithms inside the geodesigner! :-)

Thank you for the info....

Daniel, your numbers look reasonable.

If I were to further normalize my 1.3 KWH/HDD to KSF, I'm at 0.38 KWH/HDD/KSF so far this month (3400 sf home).  I have 5 and 3 ton GSHPs - both 2 stage variable speed blower units using R410A refrigerant.

Your 1.9 KWH/HDD normalized to KSF puts you at 0.37 KWH/HDD/KSF so far this month, almost exactly in line with my figure above.

The next thing to compare is how much comfort you're getting for your 0.37 figure.  I'm maintaining a 68° occupied and a 65° unoccupied  (set back) temperature.  If you're able to keep your home warmer, then roughly, you're doing better than me.  If you're running cooler, then you're not doing as well as I am.

Note that there's no analysis here for wind effects, nor do I know how to take it in to account.

All of my data (HDD, KWH, etc.) is available real time at http://welserver.com/WEL0043 .  The data I quoted MTD is straight from my first page at this location.  You can check here from time to time to do your comparison analysis.

I don't put my KWH/HDD/KSF index number on my web page because of how wind direction / speed can affect the result, because it's highly dependent on tstat settings, and because I don't have any remaining calculation capacity for my instrumentation unit (WEL).

With respect to when you should expect to use Aux heat:  I have no clue.  Perhaps others smarter than I can help you.  In my case, I never get out of 1st stage for either GSHP unit.  So 2nd stage goes unused.  And thus I don't even have an Aux strip heaters installed.  I suspect my units are sized for the cooling load needed in summer time (where I'll 'burn through' about 3300 KWH in July, my hottest month).

(The lowest temp we've seen so far down here in Dallas is 28° this month - and a high this month of 77°.  Today it was a high of 74°).

Hope all this helps.

Best regards,

Bill

Daniel, do you have the GeoDesigner Reports for your system? If so, on the Bin Analysis there is a column for Geo Run Time. When run time is at 100% is when the strip heat would be needed.

When it actually comes on is entirely determined by the tstat settings. What brand / model tsat do you have?

I'll take a look at the geodesigner run. (I didn't see it on the print that I was given, although I might have missed it..... only thing there was "hours at each temp bucket" and a cost estimate for that bucket. I may have to take you up on your offer to run the program for me, with all of our "final design" data, so that I can see more of the output from the program....

I noticed that the one you sent me from the other forum (guy in pa with issues) had some different arrangement of the report / data, so it would be interesting to see. BTW: the main differential in your run for Scranton vs, the run I had was in soil conductivity/type and that made a fairly big difference in the closed loop lenghts (mine at 150 vs his upwards of 200 / ton).

Our thermostats here are the VisionPro 8000, 8123U1006. No outside sensors. Very difficult to tell anything about how 2nd stage is calculated to turn on, or how Aux is calculated. If you have any pointers to docs on the algorithm I'd love to read them. The installer manual - I have - doesn't really give much info to set anything related to how long a stage runs vs going to next level. Nor does the tstat even tell you when 2nd stage is on. Very nice tstats, but drives me crazy not knowing..... on a way older HP w/dual fuel, I had a whiote rodgers tstat that had a yellow light come on for AUX, and another / red light for when I was on oil...... it told a lot about operation that way.... I suppose I might be able to mess around with the L line to at least get something, but didn't want to void anything yet.....

If the offer is still open Dewayne, I'll send you the manual J and the final input parameters for geodesigner. if you could send me the full report that it produces?

thanks!
Dan Z

Dan,

I have attached a Geodesigner report.  Send me all of the data you have and I will try and recreate the reports for you.

Sure am glad to hear this.  It seems we hear more from people who are disappointed, so thanks for  sharing this.

Daniel,

since you are so into knowing all of the details of your system, have you thought about installing a WEL monitoring system?

Dan,

Most tstats have a sub menu where the settings are defined that  control the heat pump.

Here is link  to a manual I found on the commercial Honey Well stat. 

You will have to see if it applies to yours.

I have been at the Honeywell site trying to find a manual...

What a pain the %*$&@(&($.

They are not going  to give you any info at all.

Yep! Almost sounds like those anti-DIY forum guys work for Honeywell :-)

Dewayne, thanks for the offer on a rerun of my geodesigner data. I'll send email sometime this weekend with all the input parameters that you need. I did find one original print that had the "run times", but it was based on the original planned loop sizes, which we later changed.....

I assume that since we are still cycling nicely in the low 20s OT (around 50% run time), Things are looking better than planned. This week we are expecting low teens a few days, so as time goes on we will test the "low outdoor temp" run times.... with the caveat that we understand that ground-temp/loop temp also goes down over time, impacting the simplistic view of this that I took.


WEL usage:
I see that you are coming up with some really good reports as are others on the forum. I am planning to do this for our units. Would you call this relatively easy to install the sensors for the main items (on/off, air temps, water temps)?  Well worth the money, by the looks of it...

Installing the sensors is the easiest part.  Configuring the WEL to give  you the data is what taxed my brain power.  Probably be a piece of cake for you.