OK, rough numbers here: HDD for Flint, MI in January 08=1175. January 09 was SIGNIFICANTLY colder with 1558HDD. So right there you should expect to use 30% more energy all else being equal.

486ccfX103000btu/ccf*85% efficiency / 1175 = 36,212btu per degree-day. That's reasonable for a huge albeit newish house.

So in January 09 you'd expect to use 1558*36,212=56.4 million btu. You got 24.1 million btu of that from gas, leaving 32.3 million to come from the heat pump. IF your non-geo consumption was similar for the two months (a HUGE assumption) then toe heat pumps used 5410kwh. Average COP would then be 32,300,000btu/(5410kwh*3412btu/kwh)=1.74.

February HDD for 09 were 1078, so using a similar analysis you'd get a COP for the partial month of 1.83, so the numbers don't seem too far out of whack.

What do you pay per ccf of gas? Estimating from you bill it seems like about $2.18 per ccf. Given your absurdly cheap electricity even at a 1.8 COP you're getting 95000 btu per dollar where you only get 40000btu per dollar with your gas. You would have been far better off with the geo taking as much load as possible even underperforming as it was.

If the geo was working properly (say an average COP of 3) and took all the load, you could expect a bill of about $450 for last January.

Well, I'm not going to do all that analysis over again, but HDD for January and Febuary were similar in Flint in 08. Are you sure the billing period corresponds with the calendar month? Mine is usually the 20th to the 20th or something.

Also note that your pre-geo electric use changed 30% from one month to another, so again, that is a HUGE variable. At least now you have submeters.

To clarify:
my gas per ccf charge is $1.059($292.32 for 276 ccf)

and per kwh in winter is $0.01048($707.88 for 6749 kwh)

Then add sales tax of $40.01(6% in MI)




Thank you very much for pointing out the discrepancy.  I did not realize winter electric rates are different!

That does make a big difference - now you get about 83,000btu per dollar of gas and only 58,000 btu per dollar with geo at a 1.8 COP. Even at a COP of 3 you'd only get 98,000btu per dollar so you'd only be looking at a savings of about 15% over your old gas system. Cheap gas and expensive (still cheap compared to most of us) electricity is not where geothermal systems shine.

These recent comments and analysis by cnygeo are on target!
The other important information here relates to the BTUs used for heating the house. Gas furnaces are pretty predictable, so it's easy to back calculate the BTUs per HDD, as cnygeo did. I updated it based on 397 CCF gas used and 1175 HDD at 85% efficiency and get 28,700 BTUs/HDD. For 7000 SF of heated space, this is only 4.1 BTUs/SF/HDD which is a good figure.

This shows that the thermal envelope of the house WAS relatively efficient, answering our questions about the "BIG HOLE" in the house.

So we're left with fewer options.
1) when the geo systems were installed, something went terribly wrong with the ductwork
2) problems with the geo system.

Unrelated to the heating usage, but pertaining to the whole house electrical loads, we see an average electrical consumption for those winter periods of 35kwh/day or 43kwh/day. These numbers are within the realm of normalcy for a large house. This is inconsistent with the summertime usage figures where we've seen huge consumption figures exclusive of the geo systems. Again, this points to a large contribution for summertime electrical bills from pool pumps or some other loads that are only used in the summer.

Based on all the information thus far, I'm sticking with my initial guess that the problem with the system(s) is the same as it was with mine - inadequate ground loop to ground thermal transfer caused by problems with the loop grouting. This will be proven if the system is measured at the start of a run for the day and it seems to output about the right amount of BTUs but rapidly decreases as the system is run. I would turn the systems off over night, or even better, for several days to a week. Then in the morning, turn them on to 60F so it runs continuously. Measure the delta-T across the coils. Each half hour of continuous runtime, make another measurement and graph the result. Some decrease is expected but I would wager that you will see a 50%-70% decrease in system output over the course of the day.

Were electric bills quoted actual reads or estimates? 10-1d pct payback is about right against nat gas round here. Curt it was since mentioned that R22 was the ref. Low pressures are typical of ETI products as they are designed to utilize least refrigerant possible. An disconnected return or such might be identifiable by comparson of zone ambient to EAT. j

All electric and gas reads are actuals-not estimates.  Brian was unable to come today to shut off the units but has promised to be here first thing in the morning tomorrow.

 

any news on this?

Hi everyone,
                        Brian was here yesterday(08/28/09) at around 12PM   and forced  all  the units to turn on for about 30-45 mins because temps were very cool and took dry bulb and wet bulb reads, amp draws etc and said he would post the numbers(probably will soon) and turned all my units off before leaving.

                        Please note that these units used all these units seen during the time Brian had these on.



Yesterday's reads  at 6PM.

                                         2Ton                           4 Ton                              5 Ton                        Main

08/28/09

00073        02

1838            04

4821           05

02662                 49               High  62F

Today's reads at 6PM with all units turned OFF.   Reads reflect electrical consumption other than A/C.

08/29/09

00073        00

1838            00

4821           00

02687                25

In other words, my home consumed only 25 kwh with no geothermal activity!

Please note that Please note that these units used all these units seen during the time Brian had these on.



I mean

Please note that these units used all these  KWH during the time Brian had these on!

Brian stated before he left that the compressors are drawing more than double the amps they should be. 

                  At this juncture I would like to say I am deeply disappointed in the apalling customer service and follow up of Earthlink Technologies in spite of repeated communication with them.  Mike Dilling took a year to get the submeters put in to finally figure out IF there is a problem. 

                   I see that there are some installers/ subcontractors who are on this forum and watching with interest, progress on this issue-so far not a single response back from the company since Russ was here in March 09 except for a measly Limited Warranty attachment on e-mail  from the leadership of the company. 
             This makes me more determined than ever to see this matter through to the very end and I will keep posting all further developments on this forum.   

              Although our installer, Brian Garno has done everything the company has asked him to the units still DO NOT PERFORM the way they are advertised.  We do understand that sometimes equipment may not function the way they are supposed to.  However, we expect as paying customers that companies stand behind their products and their service to the customers in a timely manner and take their concerns seriously. 

A company is only as good as the product it offers and a company exists because of the customer.  There is no company without the customer.  A company that does not keep its customers happy, sooner or later CEASES to exist.

Helps to explain where the energy is going - I'll bet the compressors are pretty hot burning up the excess KWH.

Best regards,

Bill

So, the question is why?
Hmm, what would happen if the the ground loops weren't rejecting heat to the ground? I'd imagine that the pressures would elevate substantially. And in the winter, when it's trying to extract heat? Well gee, then the pressures might be exceptionally low, no?

That was my thought but Joe Ami (with far more experience than I) wrote that the low suction temps and pressures are normal.

I'm still wonder how these things can be really efficient with compression ratios of 4-6 :1

I'd like to see some cooling mode pressures, temps, amps, and calculated btu output and EER

For a 24 hour period, this is impressive for an 8600 sf home.  25 KWH averages to about a 1000 W 'run rate.'  When you consider that this has to include lighting, cooking, electronics, security, computers, ceiling fans, blow dryers, washing machines, dryers, dish washers, vacuum cleaners, telephones, cable TV set top boxes, TVs on standby, stereo equipment, microwaves, toasters, refrigerators, UPS units, etc., squeezing all of these into 1 KW is impressive.

In comparison, for my 3400 sf home in Dallas, for the equivalent 'base load' (for me it's exclusion of HVAC and pool pumps), I can't get much lower than about 40 KWH per day, on average.  That's a about a 1700 W 'run rate.'  And I'm exclusively CFL lighting, with an automation system that's constantly turning off lights and ceiling fans in rooms that become unoccupied after a period of time.

Best regards,

Bill

My 3400 SF home near Jax FL has these consumption characteristics:

1) Phantoms - 4 kwh / day. Includes nothing but wall warts and control power transformers (HVAC, garage doors, smokes, phones. Measured this with fridges off and PCs unplugged

2) Unoccupied - 9 kwh / day. Includes phantoms + road floodlight, 2 fridges, well pump (2 other homes use water off it)

3) Occupied without HVAC - 24 kwh / day. This is data collected during mild periods of no HVAC use. Includes all normal residential uses - hot water, laundry, cooking, lights, entertainment

About 6 kwh of that goes to hot water since w/o HVAC there is no recovery of superheat

HVAC adds up to 15-20 additional kwh / day, but up to 5 kwh out of the 6 for HW goes away owing to superheat recovery

What are current line pressures? I think this is an occasion when I would consider digging up the manifolds and checking individual loops for heat rejection.
If all units had twice the expected amp draw then 2nd floor duct concern diminishes, but if the R/A was the source of double amp draw the R/A temp would be way high (discernably so).
Did the answer to the "what kind of grout" question come up.
Engineer: believe it or not there's not a lot of prescribed pressures in Earthlinked training. In fact you are taught that icing is not necessarily indicative of trouble.
I'll be watching to see the outcome and ETI's contribution as well.
It would also be nice to see Clarks thoughts here. Any one have tuffluck's #.........
j

Icing seems perfectly reasonable under some circumstances (obviously not good in loop water) but icing the soil around DX loops doesn't give me heartache - solid ice is a fairly good conductor and there's a whole lotta heat available from the latent heat of fusion - freezing the water.

I remain skeptical of those suction pressures and temps in heating mode this time of year, even in MI. I'm still betting on a short loop or poor ground contact issue, when and if the solution surfaces. I believe the measurements of reduced capacity, if accurate, support my bet.

Looking forward to the final answer, though.

The Icing I'm refering to is on suction line or compressor (which is of course indicative of low pressure). We agree however on our off the cuff prediction of loop/earth connection is suspect which is why I'd want individual loop Delta T's.
J