Linda, not picking on the lengthy responses, frankly I was more afraid that you'd answered the HWG question and I'd missed it.
You are correct that the Hwg has no impact on EWT. I pointed that out for a truer LWT. Climatemaster does show an installation without a buffer tank, but it wants the water flow checked to a certain delta T (I think 5 degrees). Improper flow can diminish performance.
My money is still on compaction/ time of year and your installer. Nobody has installed 250 systems incorrectly (they'd be long since out of business).
Your attention to the details though will help your installers and you optimize the system performance.

Desuper has almost nothing to do with EWT - it will actually slightly lower the load on the loop field during cooling season. I asked merely to get a handle on all possible inouts to a high power bill.

I've written at some length in the past about why one needs a preheat tank for productive use of a desuper. Here's an excerpt from a previous post concerning a system in PA

Desuperheat / preheat. The problems with not using a preheat tank are twofold:

Checking the performance chart for a 5 ton Envision and guessing at conditions in SE PA I read a hot water capacity of 4,000 Btuh or thereabouts. Suppose you have an 80 gallon water tank and you heat 60 degree incoming water to 120 dgrees. A tankful needs around 650 Btus per degree or 40 KBtuhs total. For the preheat to provide half that would require 5 hours of operation.

Suppose you get up at 7 AM on a summer day and take a 10 minute, 20 gallon shower. A couple minutes into the shower the cold water hitting the bottom element turns it on, and 35-45 minutes later (depending on water heater element wattage) the tank is completely reheated and the element switches off. Heavy use of AC will likely not occur until the heat of early-mid afternoon, but at that time there is no hot water demand so the 4 KBtuh of available desuperheat has nowhere to go (water heater all full of 120 degree water). Even if 2-4 people take morning showers, the water heater is completely recovered within 2 hours.

The same situation applies to hot water use in evening nigh time showers, laundry and dishwashing may nearly completely empty the tank, but this use is well past the heat of the day and again, the standard storage electric water heater recovers within an hour or so.

Gas storage water heaters have higher Btuh inputs so recover even faster, worsening the problem. Tankless units render desuperheat nearly useless since desuperheat can only be recovered when water is actually flowing and the result would be a preheat of only 2-3 degrees given the slow rate of desuperheat.

The twofold problems are both rate and time of preheat production.

Some trying to sell a desuperheater without the hassle and expense of a dedicated preheat tank will say that you can reduce the bottom element thermostat setting on a standard storage water heater thus turning the lower 3/4 or so of its volume into a preheat tank. Doing so is in fact impractical as it turns an 80 gallon tank into a 20 gallon tank - first shower gets the plug of hot water at the top, but the next shower if it quickly follows the first is at or only a few degrees above the lower element setting. The person experiencing the second tepid shower will not be happy if the lower element setpoint is much below 100 degrees. Not much desuperheat can be added to 100 degree water.

During the heating season the times change but the essentials do not.

Now consider a preheat tank - cheap way to do this is a 2nd electric storage water heater not wired and piped so that cold water passes through it first. That way both thermostats on the primary tank can be set so that everybody gets a comfy shower from its full capacity, and it is refilled from the bottom by the contents of the preheat tank. Meanwhile the preheat tank stores cold water awaiting preheat from the desuperheater whenever during the day it becomes available. The colder the water sent through the desuperheater, the more heat is transferred to it. The preheat tank should be as large as space and budget allows, ideally holding a whole day's hot water use. I got a pair of 12 year 80 gallon water heaters from Home Depot for under $800 total. I have $30 digital hourmeters on the water heater elements as well as the Y1 and Y2 (low and high speed) outputs from the HVAC zone controller. I can correlate HVAC operation hours with hot water electricity consumption.

Another advantage of the double tank system is the ability to wire it (assumes availabilty of a spare pair of 30 Amp breakers) and set its thermostats for same or nearly same as primary heater, and throw the breakers only when company comes for the holidays or whatever. That will disable desuperheat / preheat for reasons discussed above, but doubles household hot water capacity for special occasions.

A similar approach connects an unwired preheat tank for desuperheat to a tankless water heater. This saves space and provides the same optimization of desuperheat, but tankless units cost more and require more electric power. This variant allows for a backup source of hot water if the tankless unit fails. Another consideration is that residential backup generators can feasibly supply a storage type electric water heater (~20-25 amps) but typically not an electric tankless water heater (60-100 amps)

I'm not a big fan of tankless electric water heaters - they've been 'greenwashed' - advertised as much more efficient than conventional storage heaters since they reduce standby losses. The facts are that storage electric water heaters are nearly all 90+% efficient, and that can be improved to 95% or so by addition of tank and pipe insulation. Tankless units:

1) Have a higher purchase price

2) Have a higher installed cost (multiple pairs of high amp circuit breakers and heavy guage cables)

3) Consume much more power when running, exacerbating utility demand problems, not at all 'Green'

4) Can't flow as much hotwater in a short time - sure it is 'endless' but tepid if multiple simultaneous users

5) Are not compatible with backup generators, and their high Watt density elements and multiple, frequently switching high amp contactors are likely not to last as long as components of storage heaters

6) Those repair parts in 5) above will be more expensive than storage heater repair parts.

Ugly numbers, but I think we are on to the problem. That you have a 6 degree delta-T across the unit indicates good flow. The 110 EWT needs to come down.

110 EWT is in spec, so it isn't as though you need to shut it down and sweat it out. That said, 110 is near the top of the spec, so the unit is operating at very high refrigerant pressures and compressor currents.

Soak away ASAP - I'm glad Dewayne has a faster, greener way to get the water where it belongs. Just be sure not to damage a loop line with the soaker pipe.

If you get that EWT down to 90, the design max, your power use should drop by 1/4-1/3 and cooling capacity should rise by 10-15%. Those are guesstimates - I'm not at the right computer to look up exact values.

Good luck, keep us advised

Again, lingered on the hot water generator only due to recent experience where an empty nest house showed an appreciable gain in hot water expense with the addition of a desuperheater. Their electric water heater was metered seperately and easily monitored. We are looking at the possibility of convection loss or a sticking circulator relay, but it's very clear that the absence of a buffer tank has an impact on this situation.
Still comfortable that compaction is your problem.
J

It is hard to imagine natural convection / heat loss off relatively skinny desuper lines causing heat loss sufficient to noticeably run up a water heater power bill.

My own experience suggests that a fairly well insulated electric storage water heater set at 115 in a 75 degree room will consume around 1/2 kwh per day. I base that on an hourmeter showing 0.1 hours operation per day while house unoccupied.

I like the stuck circulator relay (or some other foulup causing the pump to run 24 / 7) That would move appreciable heat into the system cabinet.

I'm confident as well that Linda's problem lies in soil compaction / consolidation / contact with the loop lines.

Linda, an EWT of 110° after only a few weeks of operation is a sad situation indeed.

The three possible reasons for this are:


1) Being short looped. Do you have 1500' of trench with two pipes in the trench or do you have 1500' of pipe in the ground?

2) The ground not being consolidated around the pipes

3) The loops not being properly purged and some of the parallel paths being blocked. Which is the same as being short looped.

Or some combination of the above.

Hopefully the installer will step up and get the problem solved for you.

Let us know if you see any improvement from soaking.

Linda,

It sounds like you are on the right track. There is no need to worry about damaging the loop pipe with the pipe you are using to settle the trenches. HDPE pipe is quite durable. Your bigger concern needs to be getting the water down to the bottom of the trench so as to insure good consolidation around the loop piping.

Linda,

I have attached the spec sheets for your unit.  As you will see the EER at 110° is about 10.  You can also the how the EER increases as the loop temp goes down.

My desuperheater is direct connected to a gas fired hot water heater.  As a result, DSH operation made my GSHP less efficient in cooling mode, because the gas HWH increases, not decreases, the GSHP's compressor discharge.  It was interesting to analyze it last year.  As a result, until I can install a pre-install tank, I have my GSHP's DSH capabability turned off.

If your HWH is gas-fired, your DSH will make your GSHP less efficient, without a pre-heat tank.  You should thus turn off the DSH.

With respect to measuring EWT, make sure you're also keeping track of what time of day you're measuring your EWT, and be sure to compare to the same time points of previous day.  I didn't realize until recently (see the Vertical Water Loop thread here) that EWT can vary quite a number of degrees during the course of a 24 hour day, due to how fast the soil can absorb heat versus how much heat the GSHP is rejecting into the soil. 

As an example, for my vertical loop, my EWT will vary a good 7 - 8° across a 24 hour day, from about 76° early in the morning to about 84° early in the evening.

Also, with respect to your soil now dropping up to a foot over where your trench(es) is(are), sounds like your contractor needs to come in with a soil compactor machine.  Seems strange, though, that you'd have this problem with a contractor that's done over 250 installs in the Austin area.  Thus, there may be more to the problem than what is initially observable.

Best regards,

Bill

Again, thanks for all the information, especially the specs. No natural gas is available out here, so our house, including the hot-water tank, is electric. I guess in defense of our contractor, he used a different sub to cover trenches and compact soil than he usually does, and he usually does more vertical than horizontal setups. Also in his defense, the National Weather Service notes that "January to July this year was the driest first 7 months of any year." That soil is loose and I imagine hard to compact back in the trenches. My husband reports that the contractor, on site all during the install, kept saying how important it was to compact the soil, so I'm guessing that weather conditions/unfamiliar sub contributed to make the compaction unsatisfactory in the end. My husband has emailed him and we'll be talking to him again tomorrow about what's happened as we began soaking the field this weekend, and we'll address what happens next.

Linda,

I want to commend you for your great attitude through all of this. Having been a contractor for 30+ years, I have seen how most people think that if they fall out of bed, it must be the "blankity blank" contractor's fault. It is so much easier to deal with reasonable people.

I predict better days ahead for you as the ground gets consolidated around the loop pipe.

I simply had not thought of the possibility of a desuperheater backflowing heat from a domestic water heater to a heat pump, geothermal or otherwise, until now. In retrospect it makes sense. What a nightmare - paying extra for the desuper option, and then finding out that operating it increases the operation cost of both the heat pump and the water heater, and then there is the wattage of the desuper circ pump itself.

Regarding soil compaction, my limited understanding of it is that to be effective it needs to be done in lifts of no more than a foot or so. Running one now, 5 feet above the loop field, would do no good. It might even harm matters by making the top foot or so of soil LESS permeable to the water needed to consolidate the soil down around the tubes.

A compactor might have been useful if applied after the first foot of soil had been replaced above the tubes, but not now.

Others better informed / more experienced may say otherwise...

How much soil can be compacted in one lift depends on the type of soil, moisture content and type and size of compactor. 

1' to 3' lifts is the range.

You are right  about  not being able to compact a five foot deep trench after the trench has been backfilled completely.

Soaking the trench will solve the problem without any other action required.

On the desuperheater concern... if the temp in the water heater is above 120° it is a pretty sure bet that heat is going from the water heater into the geo unit and out to the loop.  Not all the way it is supposed to work.   Most manufacturers recommend that with an electric WH  you  should disconnect the lower element, and circulate the desuperheater in and out of the bottom of the tank.   I haven't done it that way so I can't say how well it works.  This is not as good as a preheat tank.  

Just wanted to pipe up with a couple of things here...

In the future, installers may consider putting a soaker hose in with the loop in trench loop systems. Then, once backfilled, run water in the soaker hose for about 24 hours. This will fill the trenched dirt with water, and settle completely the disturbed soil. An excavator pointed out to me that there's about a 25% loss of material when backfilling if not compacted correctly. (so a 4' deep trench would settle by about 1'). Anyway, we've done this on every horizontal installation, and it works wonderfully. Since the disturbed/backfilled portion of dirt is looser than the existing/undisturbed soil, the water will fill the trench completely before soaking out into the surrounding earth. We typically just use funny pipe with some holes drilled in it for the soaker hose. It's relatively cheap and can guarantee a well connected loop.

One other thing...
You mention that the system keeps you more comfortable now than the old system. I'd like to point out that if the old system couldn't de-humidify, and the new one can, the new one is probably doing more work than the old one. This would be due to the latent heat removal (humidity removal) the unit is now doing, that the old system didn't have time to do in its shorter run times. Not that this is necessarily the case, but is a possibility. I guess what I mean is that if the old system had been just as comfortably removing the moisture, and evenly cooling the structure, you'd have a closer apples-to-apples comparison on operation costs. With the new system keeping the house more comfy, and lower humidity, it's probably handling a little larger load--which may be an insignificant difference...

Indeed the soaker hose is manufacturer's spec with the 2 DX systems I'm certified by. It is a different matter with water loops however where the foot print is much larger and the heat transfer is slower a good job of compaction does the trick. Clark brought up another point I've been remiss in not asking: Does the unit have a Clima-Dry or is it set to de-humidify on the unit or the thermostat? I can't imagine humidity is a focus of cooling in your area however a unit inadvertantly set to de-humidify runs with the blower 20-25% slower.
Bill- I'm not aware of a manufacturer that suggests a desuperheater piped directly to a gas fired tank, your installation may be contrary to manufacturers installation instructions, therefore uncodeworthy (most inspectors wouldn't know any better), and could also impact warranties let alone performance/lifespan issues. You're right not to run the DSH until you get that buffer in. Any one with a DSH connected to a gas tank should check the installation manual.

Disconnecting the lower element of an electric storage water heater reduces its capacity by a factor of 4 or so on days when desuper doesn't run much or at all owing to mild weather. Losing 3/4 of hot water capacity on those days is not likely to satisfy most homeowners.

Good discussion going on here about the importance of consolidation around loop lines.

Joe, certainly w/ respect to WaterFurnace, you're correct.

WF's installation manual simply says "electric water heaters are recommended," with no cautions regarding hooking up to gas.

My HVAC contractor required homeowner responsibility for electrical and plumbing work, so I did them both.  Not having anywhere near the GSHP knowledge I now have, I thought that I could still hook up to a gas HWH with simply less hot water generation.  Later, thanks to my WEL implementation, I had the data to show that running the DSH was actually lowering my EER because of the low temperature of the compressor's R410A discharge.

I don't have room for a pre-heat tank, I too am not convinced of the pay-back with tankless heaters when considering installation cost, and I'm not yet convinced of payback either by replacing my gas HWH with an electric one.  Someday I'll figure out where to put a pre-heat tank in - until then the DSH is turned off.

Best regards,

Bill

George,
Don't be disheartened about a few weeks of less than ideal performance. While you and Linda have been very diligent of monitoring the system's operation, you could have done nothing and by next year shown a net gain. Cheers for speeding up the process and ditto what Dewayne said about not leaping to conclusions about your contractor's abilities. I spoke with another Texas native today who tells me your heat and dry spell is unusual.
Side bar for Bill, a Pre heat tank may not need to be 40 or 50 gal to be beneficial, maybe Engineer has some thoughts on the bennies of a 10 or 20 gallon tank that may fit over head or in a smaller area. If your tank is propane, operating cost projection software suggests electric tanks are less expensive to operate. We're all still learning, but interesting if WF doesn't exclude process pipe to gas tanks. Also not sold on on-demands. Why not start a thread with your conditions and available space and see if we can't find a way for you to take advantage of your hot water generator.