Don't forget that ground temperature is part of that equation. You can do calculations based on any EWT and LWT temps.
Joe

Professional TC tests are run for 48 hours. Keep in mind that what you are doing is quite different from a regular TC test.

Are you planning on insulating the drum?

60 Lbs of ice = 3 hundredths of a ton. Nowhere near enough for a meaningful test.

As Dewayne notes, these tests are run for a fairly long time to get data on the steady state heat transfer to and from the ground.

The only option that pops immediately to mind at this point might be to connect your GSHP to the two bores you have and then run it for 2-3 days on a 25% duty cycle, say 15 minutes on and 45 off. That might approximate full load operation on an 8 borehole field. However this would NOT well test for the condition of boreholes being too close together.

How about either getting the software or hiring a pro to run the soil numbers? - you are way ahead of the game since you already know soil composition

Paul, it seems to me that in your empirical study, a major component for the experiment is missing. That is the heat pump. I would expect that the drum's EWT will approach the earth's temp almost as soon as circulation starts. Depending on the volume of the cold water in the drum, soon after pumping, the water temp in the drum will also be in an equilibrium with the earth's temp, given the negligible amount of heat transfer from the drum to the air surrounding it. In order to substantiate the thermal carrying capacity of the loops, the heat transfer has to be quantified over time. Thus, one has to extract and measure the heat from the circulating water, to allow for continuous delta T in EWT and LWT.
Perhaps, a computer simulation model designed using good estimates of parameters, e.g. use of varying heat transfer coefficients representing your field strata, can be employed.
Regards, Masoud

Thanks for the replies.
Joe: The ground temp should be 51 degrees after a depth of 30' which I can confirm with my sensors. As I pump 35 degree water through the loop and warm it up the earth close to the loop will begin to cool off.
Dewayne: I wasn't going to insulate the drum so that will keep cooling the water returning to the drum.

How would they perform the regular test?

If I could maintain EWT of 35 degrees for 48 hrs. at a 50% duty cycle, then took my measurements of EWT and LWT and GPM, would that be a fair estimate of how many BTU's?

You can read all about it here

Thanks Dewayne

Forgive me for being sarcastic and I am not trying to insult you,  but this is like a guy saying I need a new car for the family so I am going to start by testing the process of compressing gasoline and air to see if I can develop a combustion engine.

There is no real need for a home owner to do a TC test before designing a geo loop.  If you are doing this for the fun it...more power to you.  Forget what I just said.

However....

If you want a well designed geo loop,  then I would suggest using the TC values that have been developed by numerous professionals and are used everyday to design geo loops.

It is very possible that you will do a lot of work trying to determine the TC of the ground at your  location and because of a mistep in your testing procedure, you come up with a value that is not even close to what the actual TC is.  If you use a faulty TC value,  your loop will either be oversized which is a waste of time and money or undersized which will cause you a lot of headaches as well as lost money.

As engineer stated, whatever TC results you come up with will be meaningless if your loops are too close together.  Since the short time span of the test will not show long term effects.

There are several software programs with built in TC values that can give you the info you need in no more than 10 minutes.  

Please don't be offended by my comments,  my intent is to offer meaningful advice.

Dewayne, I guess my thanks appeared sarcastic, it's not. I'm not affended, my thanks is sincere. This is an example of text in an email or post that the reader can't hear the expression of my voice. I went to the link and have been reading it.
As for why I'm doing it? For the following, fun, knowledge, and to save money on the install, it's kind of become my hobby. I know that a DIY is not an easy task, and by no means for the average person to attempt.
I would also like to thank this forum, for it is an excellent source of information.
Thanks again, Paul

Paul,

I applaud your efforts. Please keep us informed as to your progress and your TC test results. I would also be very interested in seeing a photo of your drilling rig.

I built the drill and the grout pump, and the worked! I will send you a pic of both if you would like.

great....dean at palacegeothermal.com

Nothing magic about that GRTI test - 5 minutes spent on their website indicates to me you could probably build a rig similar to what they are using and run your own test. I'm quite certain that within that black toolbox pictured on their site is a pump, perhaps 1/4 HP, and a 5-6 KW resistive water heater, possibly out of a Jacuzzi-type SPA. I infer this from their stated requirement of 240 Vac 30 Amp electric service and the sample report describing Wattage / BTU/hr injected into the ground.

They can infer flow (no expensive meter needed) via temperature rise across their heater of known wattage

Any standard 4500-5500 Watt residential electric storage water heater could be similarly rigged, though it would be a bit unwieldy.

Note that their test works by putting heat into the ground but that your concern (being in CT) is more about extracting it. The principles are the same, though.

I have to hand it to GRTI - great service for almost no capital outlay. I'd consider having a similar rig if if questions arose on local jobs.

As DeWayne and I have both noted, a single 2 day bore test fails to account for spacing of multiple boreholes as well as any long term borefield effects. Testing 6-8 holes all at once would take a whole lot more heat and water flow, and get expensive.

We have rented from GRTI,  the unit is pretty much as you have described. 

On a side note,  the test is only good as the loop install.  I know of a job where the  TC test was performed and the results were less than 1/2 of the average for the area.  Upon investigation it was found that the grout had settled down about 100' so a big part of the loop was just hanging in air.

The relative simplicity of the GRTI rig and the failed test you describe suggest it may be worthwhile to test each utube before interconnecting it to the field

Probably overkill, but maybe a good value add...

Only an engineer would suggest doing a TC test on every hole :) :)

I'm not sure I'd run a 48 hour test on every hole, but your own tale of a great grout void might show up in just a few hours. The well guy might be motivated to ensure proper grout placement if he knew it would be checked.

These systems aren't cheap, and a loop screwup has a material impact on capacity and efficiency.

My predilection toward hard data should come as no suprise - this isn't the first time I've been accused of an abundance of caution...

Here is an excellent website which will explain TC testing in detail...  

http://www.geotctest.com

Ewbank Geo Testing, L.L.C.
Garen N. Ewbank, CEM, BEP, CSDP
121 E. Broadway, Suite 401
Fairview, OK 73737
Office (580) 227-2358 when auto attendant answers dial 202
Mobile (405) 826-8156

"Ewbank Geo Testing pioneers in-situ thermal conductivity testing.  Ewbank performed the first in-situ (in-place) thermal conductivity test for the ground source industry in December of 1994 and today continues leading in this technology and assisting owners, architects and engineers in the design and installattion of ground heat exchangers."

http://www.geotctest.com/livetest/readytotest.jpg