We were talking of many options in the beggining stages of the project, and Rehau stuff came up, as well as the geo clips on std tube. The Rehau stuff looked like a larger hassle to install as the tremie has to be threaded through the whole thing before insertion and the parts and manifolds and multiple holes into the basement were a lot of extra cost. None of this stuff seams to be standard in my area. I paid for the geo clips myself and he agreed to put them on. I bit more time for him, but in the grand scheme of the whole job, not a big deal. If a serious snag occured in the hole due to partial wall collapse, etc, then the clips may have been a real bear to deal with. For my geology (clay and shale), they worked.

The vid online is in Jersey, so not sure what that geology is...

Thanks for the input. What did the driller charge per 260' hole? Any idea what his charge is for an extra (ie, incremental) 20 minutes?

Did driller reduce loop size due to the additional btus transferred by the clips?
.....any other quantifiable justification for even modest added expense?
Not trying to bag on anyone, I just don't happen to market things that don't justify added expense.
J

Cost per foot to drill and install loop with grout, $6.00 per foot. Cost for a loop @ 260 = $1,560.00. Time to complete one borehole? I will round up to make the math easy, 60 minutes. The cost for 20 minutes of my time while drilling $520.00. Your actual time to drill may vary but you see my point?
The construction of vertical exchangers is about efficiency and your production rate. Anything that impedes that process or slows it down must return a very high roi to offset the time penalty.
Eric

Eric,Is this right:
Total cost without spacers $1,560 for 260' hole.
Total cost with spacers $2,080 ($1,560+$520) for 260' hole.
Although the need for this (or the spacers for that matter) is questionable, could I get a 346 foot hole (33% larger) for $2,080?
Maybe a person would decide to go with just a 20% larger hole of 312' for $1,872.

This reminds me of an old joke.
If it takes 1 hour to dig a hole 2' long by 2' wide by 2' deep, how long would it take to dig 1/2 a hole?
There is no such thing as 1/2 a hole.

> The hourly cost of adding the clips during insertion is not the same as drilling time costs in my book.

Of course, it should not be. It's not hard to see that that issue and/or higher drilling costs can completely change the answer from negative to positive ROI.

My conclusion is that clips are very doable, definitely add to thermal performance and the ROI depends on the situation (ie, is not always negative). I suspect that clips near the top of the loop have a better ROI than ones near the bottom because of reduced cross talk type heat transfer and lower thermal conductivity.

Posted By jonr on 05 Aug 2010 11:59 AM
> The hourly cost of adding the clips during insertion is not the same as drilling time costs in my book.

Of course, it should not be.

If this was your business, and you were booked on your drill rig, wouldn't you want to be fully compensated for additional time spent on site since the rig and crew could be at another site drilling at full rate?  If not fully booked, it's a personal choice the owner would need to make as to full rate, or something less.

I don't understand why my electrician won't cut my neighbor a break if the electrician is at my house anyway.  After all, he is saving travel time, gas, etc.

If I'm doing something that puts more or less wear and tear on equipment and uses more or less materials, doesn't it cost me more or less per hour? But yes, personal choice - hence the word should.

I have no opinion or comments as to how much such a cost differential should be.

I do understand why the last service person I hired cut me a break - because he was already at my neighbors.

Dear All

I've read the thread with interest - being the European Distributor for GeoClips, I hope that I can shed some light.

The UK is about 10 – 15 years behind the USA in Geothermal installation, but catching up fast, mainly because we can learn from your mistakes.

I am convinced that GeoClips can save customers money – which is why I wanted to Distribute them - because if you use a qualified designer, using something like Gaia’s GLD software to design and optimise the system, you can shorten the boreholes (Loops), because of the improvement in thermal efficiency when Loop pipes are separated, even by only an inch or so… IGSHPA have done the work, and it is verifiable using the basic IGSHPA Design Equations, found in IGSHPA’s Certified GeoExchange Designers course “Grouting for Vertical Geothermal Heat Pump Systems – Engineering Design and Field Procedures Manual” (Pages 2-9 on…), or the proprietary software.

Drillers don’t seem to like GeoClips because:

• They are perceived as “Another thing to go wrong”, and an added cost – it is easier not to use GeoClips and blame something else, if the Loop get stuck half way down, as they sometimes do. If a bare loop will go in to any given hole, a GeoClipped Loop & tremie will – the GeoClips do not protrude beyond the Loop pipe, for this reason. I think GeoClips are better than the Rehau spacers, because they are smaller when closed – making it easier to install, and bigger when open, giving better thermal performance – but I would say that...

I assisted with installation of a UK Loop using GeoClips, in Liverpool, passing through shale and coal measures, all without trouble (http://revver.com/watch/1242935). Installation of a 300’, 1.25” Loop took 16 minutes, using a crew that had never used GeoClips before. If it’s taking longer, you’re not doing it right.

The real benefit to the Driller is actually in an increased productivity – fewer shorter holes mean you can drill more jobs - and earn more money - with the same rig.

Also, GeoClips give:

• A guarantee that correct grouting procedures have been used – i.e. the tremie has got to the bottom of the hole, and grout has been pumped ‘Bottom – Up’

• Every borehole installed (using GeoClips) is a “Standard” installation giving the maximum theoretical performance for the known geology– if geology is well known, you can safely drill shorter design lengths, if it is unknown, you can be sure that your client will get the best performance for the length you drill – good for your contract liability insurance, and referrals.

To try to answer the ‘Which is best’ question, and to substantiate my claims for GeoClips, I recently undertook a 3-week Desk Study using Gaia software, and wrote an article for Geodrilling International magazine, looking at the ‘Best’ borehole configuration, taking all Drilling and installation costs in to account; the major findings were that:

• The shortest - but slightly more expensive - borehole, for a given Heat Load, is achieved using a Double (4-pipe) loop, Thermally conductive grout and GeoClips in a 6” hole - (105’ shorter than an unrestrained Single Loop, TC grout in a 6” hole).

• The cheapest installation, however, is a Single (2-pipe) Loop in a 5” hole – saving more than $1 per foot/borehole length –(60’ shorter than the unrestrained ‘Control’ Loop).

I am happy to e-mail anyone interested in some bedtime reading a copy (2mb file).

Posted By jonr on 05 Aug 2010 12:51 PM
If I'm doing something that puts more or less wear and tear on equipment and uses more or less materials, doesn't it cost me more or less per hour?

Sometimes.  That's why I mentioned booking level and personal choice.  There are probably other factors as well.  Some drillers may charge less, some full rate.  Generally speaking, I'm all for getting good deals as long as the contractor does a good job.

I am not trying to keep this debate raging, only clarifying some finer points. Time is money, period. The only time I make money is when the bit is at td and turning to the left. If you require me to stop that proccess it costs me money. If you require me to slow production it costs me money. If it costs me, I charge you.
I would also like a definition of "slightly more expensive" to yield a 60' shorter bore length. I do not mean any disrespect but that is the standard Rehau pitch. I should know I heard it live from the northeast regional mgr, as well as reading it on the intranet. I have an onsite appointment with him and am going to find out about costs. My point is when you are really serious about drilling it is cheaper to drill than add enhancers and shorten drill depths. Also the bore diameter is a huge factor that is based on rig and tooling. We typically put 1.25 loops in a 5" bore and .75 loops in a 3.5" bore. Also when you get serious about drilling you realise that the only reason the loop has trouble going down the bore is that it was driller error.

In the video, it seemed pretty obvious that installing clips
required one extra worker on site while the loop & tremie
were being pushed down the bore.  Does he work for free?

Also, the loop "crosstalk" discussion sounds suspiciously
like a sequel to John Cleese's "Ministry Of Silly Walks" skit.

Anyone care to calculate the BTU/hr "short circuit current"
for tangential quasi-contact between two HDPE pipes with
an interior-to-interior temperature difference of only 5-6°F?

BTW, be sure to account for the fact that both pipes are
100% embedded in a more-conductive-than-HDPE matrix
about 20°F hotter/colder than the fluid inside either pipe.


"I would advise you Sir, to study algebra, if you are not already
an adept in it: your head would be less muddy, and you will leave
off tormenting your neighbors about paper and packthread ..."
- Samuel Johnson (1709–1784)

A "Python" fan.

This thread may be more like the skit where the guy walks into an office looking for an argument (that he paid for) but winds up in the verbal abuse office instead.

Posted By geome on 05 Aug 2010 03:10 PM
A "Python" fan.

This thread may be more like the skit where the guy walks into an office looking for an argument (that he paid for) but winds up in the verbal abuse office instead.

No I didn't...Yes You did... no I didn't....."wait this isn't an argument it's simple contradiction".....No it isn't....yes it is.....
Oh yeah, geo chat, k.i.s.s.
Simple is subjective, no benefit to taking the local driller out of his or her comfort zone (assuming design ewt is met).
J

Just a couple of things to be aware of:

A 300' hole takes about 10 minutes to install the loop with clips, total. Not 10 minutes longer than it takes without.

The other thing to remember is that the tremie is already installed, at the same time. How long does it take to get the tremie in, after you've drilled the hole? - extra time that costs money...

Will the tremie get to the bottom, if you've delayed installing it, or has the hole collapsed in the mean time?

Could it be that some drillers don't like using GeoClips because they use more grout; when you don't put the tremie in right away, holes don't often get grouted from the bottom. As long as the hole is full of water it will work ok anyway, but you can't guarantee that it will always be full. And it's hard to prove later when there is a problem.

When a hole collaspes, it is quite often where there is a water vein, if only grouted from that point, it is very likely that you are grouting off the water source that would keep the hole full of water. When the bottom part of the hole dries up, it is not going to perform properly.

From an owner or Architect/Engineers point of view, I would insist that the tremie go in with the loop pipe, whether clips are used or not. If the tremie is going in anyway, there is virtually no time lost adding clips, but certainly added value for the customer.

Good points, but.....
Hole collapse=driller error
not grouting from the bottom=non proffessional
tremie going in with the loop=un necceassary
tremie pipe can be measured to verify depth insertion/ our engineers often measure and mark, and count grout bags.

These things would be considered crutches and excuses for drillers who are not serious about drilling. I am sick and tired of drillers being portrayed as a bunch of hill billies whose main objective is to cheat the customer/designer on the drilling. While this does go on, there are also drillers who are very intelligent about geo and drilling. That is why water well drillers are often a poor choice for loop installation. Even the IGSHPA course was slanted. When I stood up and called a spade a spade the instructor was carefull not to offend, but I am sure when it was off to the next course location it was back to drillers are hill bilies routine. Even the IGSPA drilling video shows a bunch of drillers taping a snow fence post to the bottom of the loop! wtf.
Eric

Eric, can you tell us, or PM me if it may open a can of worm here, more about hole collapse and driller error? Or maybe you can point me to a source on the internet. Thanks

I know this may be a dumb question, but since most of my geo projects involve drilling through a limited amount of dirt and then rock the rest of the way, is there much of a chance that the rock part of the hole will collaspe whether we hit water or not?

Alton,
I have said before that the hard rock bore is where this clip technology as well as the double loop is really going to shine. The potential of a rock bore collapsing are slim though anything can and will happen given the right day. The smallest rock hammer is 5.5 inch or 6 inch. That is the size you must drill. It only makes sense to install the most pipe in that size hole as will fit. Or make sure the pipe you do install is forced out by spacers to the outside of the bore wall. Also understand that to run a rock hammer is slow and costly per foot to construct. 1 foot per minute penetration would be fast drilling. 20 feet in twenty minutes cost x. The trade off for twenty minutes to install clips as opposed to only gaining twenty feet of bore length is a no brainer.

Geome,
When doing mud rotary drilling the drilling fluid must cool the bit face, remove cuttings from the hole, and provide a stable hole through the hydraulic pressure of the drilling fluid. When drilling in unconsolidated formations holding a stable hole is paramount to the success of the bore. Controlling the hydration of shale or dry clays or sealing off a coarse gravel or stone formation from sluffing in and collapsing or closing the bore are what is at stake. That being said it is the drillers responsability to see that it is accomplished through the proper control and application of different drill fluids for any one particular drill site. If a hole collapses or td "total depth" is not achieved it is the drillers fault, not the formations.
Controlling your mud is the biggest downfall of most mud rotary drillers. Most use "spud mud" which is water and anything that they encounter. The problem with spud mud is that the hole controls you, not the other way around. I use a full range of additives to control and handle all manner of formations in regard to my mud program, most drillers do not. When you get serious about production drilling this becomes self evident.
Questions?
Eric