Small and crude GSHP for a Michigan garage

[pick1e]

Originally Posted by North_Pole_Guy

Have you ever given thought about just driving a 2" sand point with a jackhammer?

I thought about this a little more but ruled it out since pipe that size goes for about $40 per 10ft section, and that would basically triple the cost per foot of my ground loop. For my shallow boreholes I'm happy to just dig by hand. It's green and a good workout. *flexes biceps*

[pick1e]

The other day I was able to finish digging down to 24 ft. I'm going to call that good, it will allow me two lengths of 10' copper pipe below the frost line.

Now the question arises how to connect to feed lines that don't need to be copper. Still thinking about that.

[RobertSmalls]

Now that it's done, how much did the borehole cost, in terms of time and money?

I'm trying to develop a rough idea of how much this costs versus having a professional well driller come by, versus a pit or trench type arrangement.

[pick1e]

Originally Posted by RobertSmalls

Now that it's done, how much did the borehole cost, in terms of time and money?

I'm trying to develop a rough idea of how much this costs versus having a professional well driller come by, versus a pit or trench type arrangement.

Well lets start with the tools:

3" manual auger from Ebay -- $45

Iron pipe extensions:
3/4" x 3' -- $6
3/4" x 5' -- $8
3/4" x 10' -- $11
1/2" x 10' -- $10

3/4" x 1/2" reducing coupling -- $2
3/4" x 1/2" reducing bushing -- $2
2ea 3/4" coupling -- $3

Harbor freight pipe wrenches:
2ea 24" -- $24

Breaker bar with hatchet end:
Hatchet from harbor freight -- $8
12' length of 1-5/8" fence rail pipe -- $18

Ram pipe tool:
1-5/8" x 21' fence rail pipe -- $30
2" x 1' fence pipe welded to end -- $2

Large post driver -- $30

-----------------------------
Total: $199


The fence pipe was given to me and the driver was loaned so I'm estimating on these from prices published on the interweb. The post driver looks home made and it is massive but Tractor Supply has a large driver for $25.

So it was about $120 out of my pocket. That's a lot for one hole but that's all tools, so it will all be used for the other holes.

I didn't use any power tools, so no additional fuel/electricity costs. Maybe 15 minutes of time and materials for my friend to weld the homemade tools.

As for time I didn't measure exactly since it was incremental and sporadic. I worked on it here and there, maybe 45 minutes after I got home or an hour on saturday morning... But I would say about 12 hours all together. Now that I have the tools and I know what I'm up against (not wasting time augering rocks when they need to be pounded) I'd estimate I could dig the same hole in 8 hours, possibly faster. It was also between 15 and 30 degrees any time I was out there so that makes it a little tougher I think. I will measure more accurately for future holes.

This was just by myself too, if you had some friends and beer it would be quick work. I was out of breath lifting 20ft of pipe out of the hole, with friends taking turns it would be far easier.

I will do a heat test on this hole but I'm planning on needing 4 more holes. The only additional cost being maybe a new pair of work gloves

[AC_Hacker]

Originally Posted by pick1e

The other day I was able to finish digging down to 24 ft. I'm going to call that good, it will allow me two lengths of 10' copper pipe below the frost line.

Congratulations. Keep it up!

Regards,

-AC_Hacker

[pick1e]

Haven't had any time to work on the ground loop (and it's currently 1 degree F outside) but I did receive my Arduino toys in the mail.

The Arduino Uno came assembled but the data logger shield was a kit of PCB and components. Under $55 for these shipped. I also got a few LM35 temperature sensors at $1.71 apiece- I intend to bury them in the earth.



I look forward to using this little guy for a million projects. Hopefully it will eventually be re-purposed as my controller.

[RobertSmalls]

[QUOTE=pick1e;11347]I intend to bury them in the earth./QUOTE]Make sure they're RoHS compliant! I'm happily using Sn/Ag/Au solder. Sn/Sb is the kind of stuff that gives lead-free a bad name.

[pick1e]

Originally Posted by RobertSmalls

Make sure they're RoHS compliant! I'm happily using Sn/Ag/Au solder. Sn/Sb is the kind of stuff that gives lead-free a bad name.

My sensors are RoHS. I normally use 60/40 for electronics but good point, I will use some lead free for these. I should use it more often for electronics but unfortunately it just doesn't behave the same as leaded solder in certain situations. Of course I've never run across anything fancier than plain silver bearing solder so I've never tried it.

As an aside, I live within a stone's throw from a handful of GM plants and Dow chemical world headquarters so I doubt there is anything I can add to the ground that isn't already there- even if I tried

[pick1e]

I now have the Arduino with the data logger shield from Adafruit.com logging readings from 6 LM35 temperature sensors. I need to calibrate them a bit since they can each be off by 0.5°C (0.9°F).

The Arduino has a 10 bit ADC which means a resolution of 1024 voltage steps it can read (the sensor output is linear at 10mV per degree). Right now I'm using a 3.3V reference voltage which gives a resolution of 0.32°C (0.58°F) but I intend to switch it to a lower reference and hopefully get a resolution of 0.12°C (0.22°F). Not that it's really necessary though.

I logged some temps to try to calibrate the sensors by reducing their variance. Below are the graphs of raw data and then the corrected data from the sensors. The solid black line is the average of all the raw temperatures (1st graph) and the solid red line is the average of all the corrected temperatures (2nd graph). I placed them both on both graphs for visual comparison. The correction looks good to me- less variance while maintaining the same average. This was with the logger in the fridge. I also found out that our fridge was too warm

[pick1e]

I re-calibrated the LM35 sensors on the Arduino tonight with a lower reference voltage to achieve better resolution. The adjustments look pretty good!







I re-tested in the fridge:









Lastly, a photo of the calibrator: