DIY well drilling / trench digging for GSHP
 

It seems to me that the #1 obstacle in building a geothermal system is the digging. Even the heat pump itself isn't too difficult as you can simply buy an pre built unit; albeit for a lot more money than one can make their own. There have been some valiant efforts on this front in the heat pump manifesto but most people there that have described their processes in any great depth have all run into various problems with getting down to great depths, such as 100 - 200 '. Let us here discuss the methods of drilling and digging at home without subbing out the work to a well driller or excavation contractor.

I will keep the first post of this thread updated as time passes with links to relevant posts and news.

Evolution Of Well Drilling
 

I wonder if DIY well diggers know they need a permit to drill??

Portable water well drilling rig, How to drill a water well

Looks like this is the place for this so here I go. If you are going to be drilling a well, by far your best choice to power your drilling platform would be a nice gas motor in the 4-8HP range which has its high RPM's geared down to produce high torque. For some people here though, having a nice reversible electric motor can bring with it some nice benefits such as noise level and reversibility which is a boon in attaching and removing drill pipe extensions. Also since this is EcoRenovator, why bring another gas engine into it :p

Before I get into electricity stuff, let me caution that my degree is in chemical engineering so my electrical engineering skills are a tad rusty, please feel free to correct anything that I don't get quite right here.

So after much research there are a few good sources for electric motors with similar power ratings to gas, electric vehicles and treadmills. Motors for vehicles tend to be rated for the 12-24Vdc range as they are going to be run off of lead acid batteries typically, this means that for high power loadings, they are going to require very high current. 1HP is ~=750W so a 1HP motor is probably drawing ~800W from the batteries which at 12V is almost 70A! If we're going to power this off the wall outlet the power supply becomes non-trivial at these kinds of loadings.

Treadmill duty motors on the other hand are normally designed to be run using ~130Vdc which makes it very easy to just run AC current out of the wall through some form of rectifier and power the motor directly. On top of that, treadmills and most other exercise equipment have the tendency to be used for a few months or so only to be forgotten and shoved into the corner when that good old American laziness sets in and there is normally a very nice selection in your local "for sale" section.

And now here's the one I recently picked up.
https://lh4.googleusercontent.com/_N...0/DSCN0136.JPG
As you can see, I've found a 130Vdc motor that has a full speed of 6700RPM at at that speed draws 18A and puts out 2.5HP. Below is the conversion of horsepower to torque
http://upload.wikimedia.org/math/4/9...bb30fd12da.png
From this we can see that at full speed, this motor is only putting out ~1.96 ft*lb of torque which is far too low for drilling. But if I were to gear this down at 60:1 we're now up to almost 120 ft*lb of torque at ~110RPM. That much torque will move some dirt and rocks.

Now for the other components of my haul
Power control board
https://lh3.googleusercontent.com/_N...0/DSCN0133.JPG

Toroidal AC choke
https://lh3.googleusercontent.com/_N...0/DSCN0137.JPG

sliding potentiometer
https://lh4.googleusercontent.com/_N...0/DSCN0135.JPG

Here's a schematic of the layout
http://www.instructables.com/files/o...NMFMEG9UME.pdf

Ok, so been reading up on types of controllers, and It looks like the control board is using some form of TRIAC (TRIode for Alternating Current) or SCR (Silicon Controlled Rectifier) to provide the pulse width modulated DC duty cycle to the motor. In effect, it's taking the 60Hz AC and rectifying it into 60Hz DC current pulses of a width varied by the sliding potentiometer.

Due to the fact that these controllers use relatively low frequency pulse modulation, a motor connected directly to the controller would end up with very jittery operation and thus it needs the inductor or choke to smooth this out. Inductors resist changes in current flow and will store the pulses in the form of a magnetic field. So the choke is also a must if I want smooth torque at low speeds and will help ease the strain on the motor.

Where I live we have an abundance of rock. In fact it some times seems like we don't really have any soil, just rock all the way down. I'm thinking that if you are either in a location such as I am or if you strike rock in you drilling you won't make it with 2.5 HP, with any torque. In the heat pump manifesto a fellow named Vlad I believe made some giant rig that was gas powered and he was using tri cone bits. As I recall he even had trouble getting down too deep and decided to only dig to 70'. He never explained why this is as far as I recall.

some do, but I bet many choose to ignore it. The regulations that surround well drilling are mostly in place for the purposes of preventing aquifer contamination which presents a risk to public health and safety. The regulations are somewhat more relaxed in most states for drilling holes that will not eventually exchange water with aquifers, such as closed loop geothermal wells. From my reading these types of wells only have the requirements that the wells are back-filled with some form of grout to prevent cross-aquifer or surface to aquifer contamination. Also as AC states in his other thread, closed loop geothermal wells must be done with fusion welded pressure tested HDPE piping so as to not leak.


In the state of Oregon, you need a permit and someone who is licensed as an Engineer or a well digger, but the permit costs are far less than costs for water wells. In my case I am currently an engineering intern as far as the state is concerned, and the requirements for being a state certified engineer is 4 years of working with others who are. But in my current job with Intel many are not, as certification is more for contractors who work on government contracts. My plan currently is to work with my friend who is.

I have been reading well reports for water wells in my area, and it looks like we are on clay to sand down to 100' on average, so I may be ok

What about down the hole hammer drills? Doesn't sound like something that you could DIY. I wonder how much such gear costs. The house I'm about to move into has a decent Buderus boiler (gas fired) and radiant baseboards so I'm not particularly itching ATM to start digging. But some day the boiler will buy the farm and I will have a huge PV array so geothermal will start looking pretty nice. When I install the HRV I will make sure to size the duct work for geo. But the obstacle is the digging. I may have to just bite the bullet and hire a well digger. I will be conducting an experiment this summer. I will be cooling the computers in the house geothermally. I want a 30' well. Once all of the renovations are done I'll start thinking more seriously about that. For now the giant bank of radiators I have for cooling will be sufficient.

BTW, if anyone thinks a certain post in particular should be listed in the OP let me know either via PM or by posting here. I'm toying with ideas of how to organize the index. I'm thinking about by topic and by poster.

So at 100' it goes to rock? How many well holes do you need to dig?

I have two donated treadmill motors and controllers and wonder if one could be for a clockwise rotation and the other for a counter clockwise? I am told too that my soil should be clay to sand also. Easy drilling I hope.

Most of the reports stoped after they hit the aquifer so I don't know about beyond that. But they don't mention an actual rock layer. As for the motor, it's DC so just put in a switch to swap the polarity to the motor and same motor spins both directions

Oh and for 1 ton of heat transfer in my area I will need 200' of pipe in place under 10' of ground so right now I will probably aim for 5 or so 50' holes

How well do you know the heating requirements for your house?

There are a couple of ways you can do this...

One way is to look at the amount of fuel you consumed over previous winters and average it on a per month basis. Then design for your worst month. If you don't have your bills, the company that sold you your fuel still has that info. I'm not so sure if the fuel company will give you that info for previous owners.

The other way is to do a "Manual-J" type of analysis. This method models the insulation type and window type and surface areas and your inside preferred temperature and the seasonal temperature for your particular location and comes up with an overall heat loss.

I don't currently have Excel installed on my computer, but I have found what appears to be Manual-J in a downloadable Excel form.


Additionally, I have found a Manual-J training video here.

And also, Watts Radiant has a free software tool called RadiantWorks that will do a heat loss calculation for you.

The heat load (AKA: heat loss) calculation is pretty important and I have used all of the approaches shown above, and in addition, I have done real time worst-case severe winter weather monitoring of my BTU requirements using electric heaters and Kill-a-Watt meters. I have then compared all of my approaches to get a good idea of how much heat I will actually need.


When you've got your drilling rig working, and have found how deep you can go, you'll probably want to do a heat transfer test (that test hole will become part of your loop field) to determine thermal transfer for your actual site . Your estimate of 200 ft/12,000 BTU is probably really close, but by going through the heat transfer test steps, you'll have the opportunity to familiarize yourself with HDPE welding, and hole grouting, and you'll be more assured that you're proceeding along the right path because your heat transfer test will give you the information you need to combine with your house heat loss information, to know exactly what the minimum loop size must be.

-AC_Hacker

What is out there to calculate for your pump? In other words, if you have 10-50' wells or 5-100' wells which would be more economical?

I'm not sure that matters as the head pressure and GPM would be the same for both scenarios. But digging fewer and deeper wells would probably yield better results for garnishing heat as temperatures stabilize the deeper you go. The problem is, again, getting a well 100' deep. Hence loop fields like AC_Hacker's.

I haven't done a test well yet. That should determine the depth. I don't want to find out after we dug a hole 200 feet and the pump won't work at that depth. This brochure shows that it doesn't go very deep..... http://www.bdmfginc.com/_GT_Brochure.pdf

There has to be some kind of pressure loss when you go up then down one then down and up another, and another, etc.

There is no difference is the total amount of vertical distance the water has to travel. It makes absolutely no difference as far as load on the pump is concerned. The only thing you have to loose with more shallow wells is efficiency of the loop, as I mentioned earlier.

What there is out there is a set of manuals on this very subject. They may not be so cheap and they may not be a snap to read, but they are the very best source of information on this subject I know of.

If you are even thinking about a DIY GSHP installation, you at the very least should buy CLGS Installation Guide (#21020) - (The "original" Installation Guide). It is packed full of all the information you are interested in here.

So $100 is expensive for a book, huh? Just think about how much money you will save if you do your own GSHP... $100 is pretty small, especially compared to how much you will know going into this endeavor.

Regards,

-AC_Hacker

Last January we used 95 therms according to the gas company. This is split between the 15 year old gas furnace and our very nice tankless water heater. 95 therms in January works out to be a bit over 12,000BTU/hr. This January was a bit warmer, but I've also dumped some extra insulation in the attic and sealed up some obvious leaks around doors and windows so we used 70 therms.

For the summer, my plan is to get something on the order of 200' of pipe under 10' of depth (where ground temp doesn't vary as much). 5X40' holes will give me exactly that and 50' sounds marginally doable from looking at well reports in the area, though this could quickly change. Once I get this pipe in, I want to setup a heat pump in a cooling config and just shove the air->refrig evap in our existing duct work so I can use the existing furnace blower to pump some cool air through the house. We currently have nothing in the way of AC so any cool air in the house for those 10 days Portland gets hot will be an improvement.

For the winter, we already have a tankless water heater that puts out far upwards of 12,000BTU/hr (don't have the exact #'s on me but its on the order of 2-4 tons I believe) and my goal is to setup a water-water heatpump as a pre-heater for the tankless. If I can get a continuous flow of 90F from the heatpump, the tankless can easily crank that up to 140F and run that through a radiant floor. And the furnace will still be functional in the event we need something to fall back on.

and yeah, what he said. You aren't pumping water up from the bottom a 200' hole, you are just circulating a close loop and the changes in potential energy all cancel each other out so your only head requirement is the resistance of the total length and all the fittings/valves/whatnot you have in the loop.

More holes means more pipe. I need 200' of hole under 10'. If I do one 210' hole I use 420' of pipe. If I do five 50' holes, i use 500' of pipe for about the same heat transfer ability.

Marginally Maritime...
 

This is really useful information for your project.

For my project, I did a similar calculation. I now think I was being overly optimistic.

Where loop fields are concerned, size really does matter... bigger and deeper is better.

For one, I under-estimated the effect that temperature changes close to the surface would have. I also learned there is also a temperature change time-lag (more depth = more time lag) factor that I now appreciate more than I formerly did.

Last winter, I ran a test, using my little heat pump which I had previously measured to output around 4500 BTU per hour. I hooked it up to a car radiator and had a box fan blowing through it. I set it up in my basement which is not insulated and I let the thing run initially without any thermostat, for 24 hours a day, 7 days a week, for about two months. I had never used the radiator and fan setup before, but I just wanted to see how everything worked out on a sustained basis. All I logged was outside temperature, basement temperature, and loop water temperature.

Since I only went down 17 feet, which is really shallow, my whole loop field is greatly subject to the transient temperature swings, but since the heat travels slowly, the effect was somewhat muted because the cold pulses (and warm pulses) took a while to work their way down.

But still, whenever there was a period of unusual chill, I could see it clearly in the loop water temperature change about three days later... same for an unusually warm period. If there was a sustained 10 to 15 degree downturn... three days later, I would see my loop temp drop by two or three tenths of a degree.

There was also a warming effect caused by significant rainfall... with a similar time lag as above.

This diagram from the CLGS Installation Guide (#21020) book I mentioned previously helped me greatly in understanding what was going on...


Long Term Loop Temperature Decline

I also saw a steady, sustained decline in loop temp over a two month period, which was due to heat removal from the ground. During this time, on a couple of occasions, I turned the heat pump off for a day or two, to make changes in my heat pump setup, and I could see that the loop temp had 'sprung back' somewhat, but subsequent running of the heat pump showed that pretty quickly, within a matter of hours, not days, the loop temp worked itself back down to near what it had been before the equipment shut-off... which indicated to me that the full heat reserves take a considerably longer time to completely restore than I would have guessed.

My conclusions from all of this...

Where loop fields are concerned, size does make a difference... bigger and deeper really is better

My initial idea of a shallow borehole loop field does work, but my optimism as to the total available heat is now somewhat tempered. In other words, I learned something from this experience.

I would expect that there would be similar behavior from a loop field that was deeper and larger (larger in terms of loop filed size to heat load). I would suspect that a deeper field would reflect changes more slowly, and to a lesser degree. I would think that a bigger loop field would show similar changes but again, to a lesser degree.

Assumption Error

My calculation regarding boreholes, that...

200 = 200
200 = 2 x 100
200 = 4 x 50
200 = 8 x 25
200 = 16 x 12.5

... is not correct, and that the shallower the boreholes are, the greater my error was. So a loop field composed of shallower boreholes will require more boreholes do deliver the required heat. I do think that a correction factor can be developed and that the above diagram holds the key to the formulation of this correction factor.

Having said all that, I am getting useful heat from my loop field, and possibly enough useful heat to meet my original design target... because serious insulation is also part of the project.

When I originally laid out my loop filed, I left enough space to add an additional 7 or 8 boreholes, which I can definitely use. Due to my arm injury, I may or may not be able to do it this summer, time will tell.

Hybrid System

When I started this project, I bought a small 3/4 Ton mini-split ASHP to see me through this project. The mini-split has worked out far better than I had anticipated, delivering reliable cheap heat, even on very cold (12 F) days, when it was obviously struggling to stay alive (low COP during that low temp, too). The climate in which I live has a pretty moderate heating degree day level of 4,000 to 4,500. Also, being as how Portland's weather is marginally maritime, heating requirements are fairly modest, compared to the central northern states & Alaska. In fact, there were a significant number of days this winter when the air temperature was higher than the loop field temperature. Those days are golden days for an ASHP.

So, my current thinking is to combine a too-small mini-split ASHP with a too-small GSHP heat pump and leverage the best qualities of each. On the days when the air temp is higher, the heat loss from the house is not so high, and the ASHP is working at it's highest COP, so the ASHP alone is capable of doing the job... On days when the air temp takes a huge dive, the ground loop temp is looking pretty darn good, especially if I haven't been drawing it down all winter, then the GSHP comes into it's own.

I still think that the best way to do the hybrid setup would feature a hydronic radiant floor. The GSHP is already a good fit, but my current ASHP is not. An ASHP hacked to be air-in and water-out would be ideal.

So it is with tremendous interest that I am watching developments on the ASHP Hacks thread.

Best Regards,

-AC_Hacker

Depends on what state/county/city they are in and whether they are on their own property. It is not uncommon for people in rural areas to pound in sandpoint wells for watering their livestock. They sell the materials at my local farm store.

I've helped put in monitoring wells with drill rigs at hundreds of sites and installed monitoring wells with hand augers at dozens of sites and have thought about putting in geothermal wells at home. I would say that if you are drilling more than 30' deep you will want somebody with experience and some substantial drilling equipment even if you are in easily drilled soft clays. If you encounter sand below the top of groundwater or below about 10' depth you will want hollow stem augers to keep the holes open while you build the well inside of them. A twenty foot string of hollow stems is too heavy to lift by hand, so even if you get a little one man drill rig and can find somebody to lend you the augers you'll need something to pull the string out of the well.

Rock can be drilled, but you definitely should have somebody with experience help you with that because depending on the type of rock you need to use different methods (e.g. down hole hammer vs. tri-cone bit).

If I were to install geothermal for myself, I would go with horizontal loop because bedrock is shallow and problematic at my home.

Well, many of us live in areas (towns & cities) that have governments that need
to completely control and tax everything they can. (Too much time on their hands).

Some of it is sensible and needs to be done, but much is just for revenue.

Sometimes, it makes me think seriously about moving to the boondocks.. :)

I'll throw one in here, as have done a couple of wells.

1st one we literally dug by hand (small air hammer, posthole digger, tripod over the hole, vacuum cleaner on blower for air. 30 in dia, 18 ft deep, supplied all our domestic needs for 25 years..

Then a 62 house subdevelopment went in 500 ft uphill, so needed a deeper well. From well logs of others (check you state registers) knew I'd likely hit good abundant water at a blue clay layer about 60-70 ft down, but heeded to go thru 55 ft of hardpan with occasional 3 ft dia bassalt and granite boulders.
Tried a rotary setup first after welding up a 30 foot tower to bolt to the back of my dozer. Twisted the shaft off every trnsmission drive I tried when hitting a boulder (including a specially machined 2 in dia 4340 shaft as have a machine shop)

Went with the old cable tool standby, welded some 4140 steel to the end of a few 5 inch billets of steel (aka old railroad car axles) and hardfaced them. Built a walking beam out of some 8" channel and 3 old trucks, drove with the truck engine.

Biggest pump I have will pump 29 GPM, did that one august and pumped all day with no drop in delivery. Hit the blue clay right at 60 ft, 5 ft of sand above that.

'Only' took 5 months of spare time, but still have a rig if I need one again..<G>

had the baby, might be a bit before you see much in the way of updates from me... but i'll be paying attention when I can

Her name is Miette ;-p
https://lh6.googleusercontent.com/-v...0/DSCN0154.JPG

Mighty fine baby you have there... congratulations!

Best regards to you all...

-AC_Hacker

This sounds like quite the setup.

Do you have any photos or drawings of this rig?

I have no idea what a walking beam is...

-AC_Hacker

Junkhound,

Keep telling the people at green building talk the truth! Their treatment of you is absolutely fantastic! When you plain tell them that they are soaking people for tens of thousands of dollars they can only respond with scorn.

I don't care if it GSHP or something else. I am poor as dirt, and so are a lot of other people. And we need to keep ourselves and our families warm in the winter. And we shouldn't have to pay more than the cost of oil heat to think we're saving money, the planet and humanity.

Bolders are always a problem. Cable tools are the grandaddy of the downhole hammer, so I'm guessing that they work fine if you are patient. How did you get the rock chips out of the boring?

Makes sense that the blue clay would seal off the water so it would accumulate in the sand layer. How did you keep the hole open/clean enough to build your well in the sand? Around here at that depth wet sand usually wants to heave and flow into your boring.

For what its worth a lot of drill rig transmissions share parts with commercial trucks (e.g. drivehead swivel=truck transmission U joint.) Unless you have your own junkyard and a lot a free time, it'd probably cheaper to hire a driller than to build your own rig.

it'd probably cheaper to hire a driller than to build your own rig.

Yah, but think of the fun I'da missed. I figured I spent about 250 hours building the rig, spent $300 on 8" and 6" sch 4 steel pipe, $80 on welding rod, had most the steel and etc. in my 'personal junkyard<G>.
Likely 'made' less than minimum wage (but tax free), way less than 'day job' wages.

Did have fun though.

Pic for AC_Hacker attached.

re: How did you get the rock chips out of the boring?
Had 2 winches on the rig, big one to pull the drill (cable wrapped around a car wheel); and a small elec motor winch to lower and raise a bail made of a piece of 4" sq tubing with a flapper at the bottom. Drill 2-3 feet, pull the drill, lower the bail and bail out the rock chips and mud.

How did you keep the hole open/clean enough to build your well in the sand?
Drilled a 6" hole down to the sand (very fine sand), then jetted a 4" coarse screen into the sand layer to the clay - used an old 'scrap' pump to pump out the water, which was laden with the fine sand for about 10 hours, after which it has been clear water for many years.

Wish I was young again like in the pic......parts were from '63 GMC truck, '71 Datsun, and '62 Impala.......probably would have more than paid to have the well drilled if I'da just put them trucks and car in storage till now???

Thanks for the pic.

The guy in your picture...


...looks mighty similat to this guy...


... in fact, I'm pretty sure you guys are related.

So, what is a "walking beam", anyway?

Also, when you did your GSHP loop field, did you dig boreholes, or did you dig trenches? And how much borehole or trench did you dig for the Tons of HVAC heating you got?

Also, when you were doing boreholes, how did you join your pipe segments? did you use existing pipe thread, or did you buy or make some other method?

Also, when you needed to force water down the borehole, what did you use for a pump?

-AC_Hacker

That old pic is fascinating. I wish it was in higher resolution, to see more detail.
(Like what kind of shoes he was wearing).

So, the idea behind that giant drill bit was, drill down, pull it up and clean off about 100 pounds of clay?

Interesting, the B&W photo DOES look like pics I've seen of Greatgrandpa (b. 1850), but no idea if related. Nearly everyone in the family has had blacksmith skills, and that drill looks hand forged?

My GGpa's dad, GGGrandpa, got so upset with the prices folks charged him when he moved to IL from Deutchland in the 1820s that he ended up building his own commercial sawmill, grain mill, and even dug his own coal mine. By the time it closed in 1965, the coal mine had provided the livelyhood for quite a few families over the previous century. So, some of the DIY and 'cheap' traits must be hereditary.

A walking beam is an engine driven arm that applies vertical motion to a drill stem or cable or pump rod. In my pic, it is the beam going from the car wheel and angling down to the left. The vertical arm on the pic is actuall an elbow (crank), one arm is attached to one axle of a welded rear end of a '62 Impala, so that as the wheel rotates, the arm moves up and down by crank action.
The drill stem can be seen hanging to the left of the tower, with the cutting edge hidden behind the fire hose. Cable goes from walking beam up to big pulley on top of the tower.

Used a 3" open vane pump driven by another car engine for the 'jet', water from the existing 30" dia dug well (with a few gallons of bleach dumped in every few minutes to be on the safe side)

Open loop, same well as our drinking water, my water rights permit allows 5000 gal per day, dumps into my pond.

Use method similar to yours for joining pipe, only used 2 old teflon coated clothes irons
vs a waffle iron...

Saw a copeland scroll this AM on ebay for $60, will bid on that, maybe think of building a HP using propane system for the barn shop.....

I always want to build one of those Walking Beam Engines with my Erector set,
but I didn't have enough parts..

Erector Walking Beam Engine - Girders & Gears

Corbett Portable Drilling Rig

Well Drilling Resources
 

I thought I'd post some well drilling resources... I will edit more in as I find them. If you're thinking about drilling holes, the time to start is now, while you have lots of fair weather ahead of you.


Lifewater, a Canadian well drilling manual

Prectica, a Dutch organization with open source manuals on various techniques regarding well drilling.

Hydromissions, a christian missionary organization that specializes in low-tech soft earth drilling tools. I tried making some of these tools... They didn't work well in rochy soil.

Baptist Well Drill - A combination percussion/sludge drill with a simple to make drill point and foot valve. Low tech and effective. It helps to have a team for friends to help out.

The Wikipedia entry

A PDF with lots of info.

Open Source Ecology - These guys have some big ideas, including a well-drilling machine. So far it's on the drawing board, without much in the way of drawings. Maybe they need help?

Regards,

-AC_Hacker

I have fallen in love with the girl on the right in that picture. Much more important than any information on well drilling would be her phone number.

She's only interested in guys that drill wells...

-AC

I'd tell you where to get more info and where I get equipment, but I don't have enough posts, sorry.

Send me an email through EcoRenovator with info, and I can edit it in with proper attributions, of course.

-AC_Hacker

Wanted to post some pics, but need to find how to upload them first