Faulty Earthlinked DX systems
Last Post 07 Jul 2011 10:29 AM by drao. 212 Replies.
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joe.amiUser is Offline
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25 Aug 2009 08:04 AM
Tinoue,
I often encourage folks with questions to employ brevity in their posts so that the wheat is not hidden by the chaff. You might do the same with your thoughts.
In your short post you made the observation that significant consumption was by other than heat pumps themselves. I concur.
Drao
I noticed installer's comment that units are attached to existing furnaces. Are these variable speed or split capacitor motors (do they go from slow to fast to slow again or just run on one speed)? Do you run constant or intermittant fans? It's been a funny year in MI with mild summer temps, much moisture and you have a large home, are you operating dehumidification independant of the cooling?


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25 Aug 2009 09:25 AM
The two existing furnaces have been converted to variable speed. The two ton is on a variable spped Nordyne air handler. When I get a spare minute I will post my temerature and pressure readinds. I also have amp draw and temp readings from the airhandlers.
Brian


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25 Aug 2009 10:23 AM

I beg to differ.

                        I may be noted that when my geothermal units are barely on as below on 08/23/09, I consumed 29 kwh my avg summer consumption without A/C.  It is obviosus that I do not have outrageous household power usage -it is not as if I turn on more lights as it gets warmer outside!

                       




08/23/09

 00062        00

1805            02

 4777           00

02360                29

              High   70F


Strengthening this belief is the fact that on 08/17/09 my units and associated equpiment including air handlers etc are guzzling power.

08/17/09

 00040       10

1650            48

 4728           18

01834         129    

        High    81F



Just to put things in perspective, in July 2008, our home consumed 2007 KWH with conventional A/C. My geothermal units were up and running in Mid Aug 2008.


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25 Aug 2009 10:25 AM
Oh, I almost forgot that we added 6 inches of additional cellulose insulation over the entire attic space to account for settling in May 2009!


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25 Aug 2009 10:28 AM
I actually have a plan.  On Aug 27th 2009( day after tomorrow) Brian is going to disconnect the geo thermal units completely for the next two weeks so I can put the last piece of my puzzle together before going the next step.


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25 Aug 2009 11:44 AM
Posted By joe.ami on 08/24/2009 8:54 PM
 What were the man j loads for the units' zones.
J
do we not have these?


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Bill NeukranzUser is Offline
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25 Aug 2009 11:46 AM
Posted By tinoue on 08/25/2009 7:42 AM
I disagree, yesterdays numbers look normal. About an hour runtime for the 2-ton and 2kwh consumption, 2 hours and 9kwh for the 4-ton and an hour and a half or 7kwh for the 5-ton, total consumption of 18kwh ...

Interesting.

I'm familiar with conventional water-to-air GSHP technology, but not with DX.  I've always thought DX was a more advanced technology, capable of producing similar or better efficiency performance.  I've been looking forward to learning from this thread if indeed this is the case.

With data collection directly on the 3 HVAC units, it seems to me that discussion on the total structure power consumption just adds uneeded complexity to the subject.

Focusing on the one "normal" day, the HVAC related data published is: 8/24, 18 KWH (just for HVAC), 0 or less CDDs, 5600 sf home.

For this particular day, assuming the HVAC KWH consumption is in cooling mode, and assuming the DX system is operating similar in efficiency to conventional technology GSHP systems, then approx 280 KBTU of heat was extracted from the structure and put into the earth.

Again, this is on a 0 CDD day.  Depending on what the low was for the day, it may well have been an x HDD day.

So my question is, is about three-tenths M BTU removal for this structure, for a 24 hour period, on a zero or less CDD day, 'normal?'

Best regards,

Bill






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25 Aug 2009 12:18 PM
Bill,
You are correct that heating was the larger requirement.
A clarification on the "higher efficiency" DX. I've mentioned before that higher efficiency is often defined by the amount of pipe in the ground. For instance a water source vertical closed loop may use 300' of 3/4" pipe/ton to accomplish the same thing as a horizontal 600' slinky. That makes the vertical "more efficient" but does not impact operating cost. The DX may only use 200' of vertical pipe/ton making it "most efficient" but it may not have a lower operating cost.
We once discussed the efficiency debate here and my posistion was (and remains); no one achieves the #'s advertised once the unit is off the test bench. Peak C.O.P. and average are different (a unit that operates on the test bench may achieve a 6 C.O.P during a test with open loop flow of 6 gal/ton but have an average yield of 3 C.O.P at 1.5 gal/ton). Units that are closed loop have lower C.O.P.'s in the mid winter bringing down the average as well.
The claims of highest efficiency are rather disingenuous in my mind (by DX and water source mfg's), which is why I tell folks the installer is more important than brand or type. If you want a disqualifying comment from a contractor in my book how about "our heat pump is the most efficient."
j


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draoUser is Offline
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25 Aug 2009 12:22 PM
Yesterday's low was 51 F .  Thank you for all the support i am getting from all of you.


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25 Aug 2009 12:32 PM
Also, if it helps, my home is all brick and insulated with cellulose(NU Wool), has low E Pella windows, even put in styrofoam(one inch) before concrete was poured for the basement(to avoid direct contact to the cold underground) and even has styrofoam (one inch ) on below grade basement walls on the exterior.  I even have low wattage spiral bulbs(flourescent) in my home.  I have made every attempt to make my home more energy efficient  and have researched extensively before deciding to put in geothermal.  I was going the final step by going GREEN with DX geothermal technology but come to find out I am just losing a lot of GREEN!


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25 Aug 2009 12:37 PM
Just a look at the #'s show that the 4 ton unit is used more and eating more Kw's. Is that the main area of the house?

Are there any fresh air intakes or duct work outside the living space of the structure? (as mentioned before, Attic space ductwork? )


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25 Aug 2009 12:43 PM
Posted By JackH on 08/25/2009 12:37 PM
Just a look at the #'s show that the 4 ton unit is used more and eating more Kw's. Is that the main area of the house?

Are there any fresh air intakes or duct work outside the living space of the structure? (as mentioned before, Attic space ductwork? )


Yeah,
It'd be interesting to see the man j load for each zone......


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Bill NeukranzUser is Offline
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25 Aug 2009 01:12 PM
Posted By joe.ami on 08/25/2009 12:18 PM

... A clarification on the "higher efficiency" DX. I've mentioned before that higher efficiency is often defined by the amount of pipe in the ground. For instance a water source vertical closed loop may use 300' of 3/4" pipe/ton to accomplish the same thing as a horizontal 600' slinky. That makes the vertical "more efficient" but does not impact operating cost. The DX may only use 200' of vertical pipe/ton making it "most efficient" but it may not have a lower operating cost.



Joe, thanks for the note.  I'll learn right along with the rest here about DX technology.

Based on Mr. Drao's latest post, for the 18KWH day, it was approximately a -1 CDD day.  Still, I'm assuming the structure has enough latent heat in it that the 18 KWH consumed was in cooling mode.

I don't agree that higher efficiency is defined by the amount of pipe in the ground.  Thus, I think you and I are agreeing here.

I think the definition most consumers have of efficiency includes operating cost.  Thus, for your examples of a vertical closed loop using 300' of 3/4" pipe/ton vs. a horizontal 600' slinky, if the KWH cost is the same for removal or injection of the same amount of heat, then I believe most consumers would agree the two systems are equivalent in efficiency.

I know little about DX.  I've been under the impression that amongst the advantages of DX, one is that, for a KWH of power, more heat can be removed or injected, than with conventional technology water-to-air GSHP units (generally).  I'll learn over time if this is indeed the case.

Best regards,

Bill



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draoUser is Offline
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25 Aug 2009 01:21 PM
Funny that you ask!  The 4 ton unit supplies the 2nd floor(1300 sq ft) and the basement 3200 sq ft.  Also, I have four zones (two upstairs on either end of the house) one on the amain fllor and one in the basement.  The 4ton unit only cools the 2nd floor(1300 sq ft) because my basement always is between 70 and 73 F ie never requires cooling -and still happens to be the biggest drain!


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25 Aug 2009 08:20 PM
Okay gentlemen here are the manual j-8 loads for the home. Flint Michigan used for reference city winter temp 1 and summer 87 dry bulb.

Total building load 112,432 BTUH net loss 52,198 BTUH sensible gain 4,877 BTUH latent gain 57,075 total gain.
System #1 Four ton unit 2 Zones Zone #1 basement 22,704 BTUH loss 6,987 net gain Zone #2 second floor 24,259 loss 15,297 net loss
System #2 Five ton unit Main floor 47,879 loss 29,590 net loss
System #3 Two ton unit Master suite/Bonus room 17,590 loss 10,108 net gain
Any other info needed please ask, I need to get this fixed
Brian


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25 Aug 2009 08:49 PM
At a glance you have 11 tons to accomodate 4 1/3 tons of cooling load which is IMHO unfortunate. I have great success close to you by not designing for 100% heating load. A greater reliance on aux. heat (again my opinion) would actually reduce your customers operating costs. While Earthlinked is very efficient, running a 5 ton compressor for a 2.5 ton load (since it is not 2 stage equipment) will cost extra.
Philosophy/personnal opinion out of the way, I don't think this is the problem here. Based on other info provided, I think there is something else going on that we are not yet privy too. Significant usage aside from heat pumps seems to be occuring. How do we account for that?
J


Joe Hardin
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25 Aug 2009 08:49 PM
Here is some data taken before I modified the loops and air coils per Russ' input. Units are in heat mode.
System #1 4 ton unit suction pressure 30 PSIG discharge pressure 17.3 degrees 210 PSIG 179.9 degrees
at the compressor
Air coil liquid line 210 PSIG 100.5 degrees Air coil vapor line 210 PSIG 175.2 degrees
Unit is pulling 12.93 amps at 243.5 Volts
Air coil entering temp is 76.3 dgrees leaving temp 97.7 degrees at 1560 cfm measured it the air handler.
Ground loop liquid 100 PSIG 53.7 degrees Ground loop vapor 32 PSIG 33.9 degrees

System #2 5 ton unit 40 PSIG 21.1 degrees suction 225 PSIG 191.2 degrees discharge at the compressor
Air coil liquid line 220 PSIG 100.7 degrees Air coil vapor 225 PSIG 189.6 degrees
Ground loop liquid 100 PSIG 73.9 degrees Ground loop vapor 40 PSIG 27.4 degrees
Air coil entering temp 78.4 leaving temp 104.6 1975 cfm at the air handler
Amp draw 21.02 245.3 Volts

System #3 2 ton 38 PSIG suction 19.7 degrees 180 PSIG 172.5 degrees discharge at compressor
Air coil liquid line 180 PSIG 89.5 degrees Air coil vapor 180 PSIG 157.9 degrees
Ground loop liquid 86 PSIG 53.7 degrees Ground loop vapor 40 PSIG 45.6 degrees
Air coil entering temp 76.5 degrees leaving temp 89.8 degrees 675 cfm
Amp draw 6.39 245.5 Volts
All three units had bypass humidifiers installed. I did not do the duct system, it is buried in a finished basement ceiling,drywall of course. I would really like to locate an Aeroseal dealer. Thanks for your input.
Brian


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25 Aug 2009 08:53 PM
I agree that designing for less than 100% heat is the way to go. After IGSHPA training I have changed how I size systems. Traing I received from ETI had me sizing for 100%.
Brian


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25 Aug 2009 08:58 PM
(edited) Great info.
Just to confirm that we're all on the same page. The numbers you're giving are based on those design temperatures with a 65F base for HDD/CDD?



A very basic test I often run, which is more accurate than one would guess, is simply timing the on/off cycles at a variety of outdoor temperatures. Of course, this is rough due to thermal mass effects, but it's a good diagnostic. So, for example, if the net heat gain of system #1 at 87F is supposed to be ~22kBTUh, and if you determine that the actual delivered BTUs is 44kBTUh, then we would expect about a 50% run time/off time. Further, from that, you'd expect 12 hours per full day of runtime consuming about 48kwh.

For more accurate diagnosis, I've installed a data logger that tracks return and supply temperatures and outdoor temperature. For most accuracy, you'd want humidity as well, but let's ignore latent energy for now. Then, you can just look at the graphs of temperatures, see exactly when the air started/stopped cooling and compare that with the outdoor temperature. You also get a live delta-T measurements. you can add an amp-clamp to monitor the compressor or air handler as well.

All of this provides sanity checking and very powerful data that can quantify operational parameters, proving that the installed system is either working properly, or not. I would however start with the stopwatch and measure fractional runtimes.




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25 Aug 2009 09:08 PM
Brian, More great data. Do you have any delta-T numbers from this summer? Also, have you tried measuring at different times of the day? Let me explain my reasoning without being too verbose. When the system starts running for the day, the ground temperature will have had an opportunity to recover towards the base ground temp. Depending on the thermal conductivity of the ground and the amount of system use, throughout the day, the ground will heat up around the loops to some degree. So the temp. drop across the coil might be 30F in the morning but 20F in the afternoon after the system has been running. The less the change, the better the ground loops/field are at rejecting the heat. If you have a grouting problem, you'll very find that your deltaT drops quickly. If you have excellent conditions, the deltaT should remain steady.


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