Cyngeo,

<!--[if !supportEmptyParas]--><!--[endif]--> We are doing indoor manifolds.  The pipe is being pressurized with air and each pipe has an individual valve connected to a common pressure gage.  Yesterday, we talked to the gas man who was testing the soil around our gas line the excavator had broken, and he said the crimp did not look too bad.  He suggested that we put a stainless pipe repair clamp around that section to stabilize expansion and contraction and reduce stress.  It would also help make sure the pipe does not re-crimp at that section as we lay the rest of the pipe.
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I have bought some sheet plastic to create a water pond so I can drop the whole pressure testing manifold under water to see if I spot a slow leak that is not showing with soapy just water.  The excavator also ran over a section of pipe that was well out of his way when he was not paying attention (he also ran over a 7’ tall by 6’ diameter rhododendron which we were sad to lose and he ran into our the corner of our metal shed crushing a corner.)  I will test that section by submersing it too.  That section is not buried, but, while it had maybe quarter inch deep dents in it from the track hoe tracks, within an hour or so, it had returned to normal shape and you could only see scratches. 

As to the antifreeze issue, I never meant to imply that we would not use it, only that the system is expected not to go below freezing in the loops.  We will be using antifreeze.

An additional note about gas line safety:  I had the gas line clearly marked by the gas company at the excavator's request, but it turned out to be about 12” inches from where they thought it might be.  The excavator was trying to save a little time and effort by digging with his track hoe as close to the pipe as possible before hand digging, and he tore the pipe right out of the ground.  The supply side had sheared flush below the ground, so the excavator decided to bury the severed end to try stop the gas flow.  Apparently, that is the worst thing one can do – the ground can fill up with gas and create a giant underground bomb.  You should just clear away (the excavator continued to dig the trench), not try to stop the leak, and let the gas dissipate into the air. 

Also, while the excavator had several clauses in his contract about not being responsible for locating and damage to underground utilities, Oregon contractor's law says he is exclusively responsible for both locating and the cost of damages.  Apparently, he is also responsible for incidental property damage, despite any clauses in his contract to the contrary. 

esger,

Please tell us that the excavator is no longer on your property.  You have much more patience than I.

As I have mentioned elsewhere, the only thing we would have done differently so far was not to dig 5' foot wide trenches - the logistics of managing the soil on a small lot were extremely time consuming. Stick to 2' wide trenches.

Posted By esger on 09 May 2011 12:24 AM
Seth,

 We are also hoping that the price of heat pumps has been coming down as their popularity increases.  The lowest bid we got in 2008 for just installing the manifold, perging the pipes, heat echanger, and heat pump was $11k for a WaterFurnace 3 ton water to water unit. 

Posted By esger on 09 May 2011 02:51 AM
What we did was to have six pipes in the 5' wide trench sections at 12" o.c., then three pipes in the 2' wide trenches at 12" o.c.  Same spacing, just less dirt to move at any given time.

DocJenser,

You are right about the ease of placement of the slinkies.  Before I started my project, I helped a DIYer create his slinkies and place them in the ground.  The problem he had was trying to make them all a uniform diameter of 32" with the coils often having a diameter of 36" as we stretched them.  It just meant al lot of pulling/pushing and definitely required two people.  His system was half again as big as mine and it took us several hours to make up all the coils with our handicap of inexperience.  I can imagine with you doing the slinkies all the time, they go together very rapidly.  I can also see from my experiences the simplicity of just unrolling the coil over having to stake the pipes at the corners as was required when turning corners, etc.. 

In my project with straight runs the coils tended to get the strange knot I've described earlier in this thread if you did not unwind them correctly.  Our pipe placement project was broken into two stages after I sent the excavator away after his third mishap.  I called the geo contractor to tell him about the hassle of the pipe knots in placement and he recommended we make an H shaped flat piece of plywood, cut it in two then reconnected to form a spool for our coils.  That worked perfectly and prevented the coils from kinking and made them overall very easy to handle.  He said his crew is experienced enough that they never have the knotting problem, but he's seen it many times with the inexperienced.   Still, even with the three times the coils got knotted, I remember thinking how much faster it was to just roll out the coils rather than create the slinkies too.  I'd estimate it probably took an hour’s worth of time total to unwind the coils, not including making and installing the plywood spools. 

The one thing the straight runs gave us over slinkies was flexibility in placement.  We ran individual sections of the pipe 30" below the bottom of gravel level of our basement slab at 4' o.c. in one place and there were a few places that we put all the pipes in one narrow trench (still spaced and in two layers) just for logistical reasons of existing shrubbery, etc. 

We were also trying to contact as much area of our limited lot as possible, and it was the engineer who showed us his logic of using less pipe with straight runs but contacting more soil overall. 

Seth,

My experience is anecdotal and very, very limited and DocJenser has installed and monitored both system types and would probably be willing to provide links to documentation to prove how slinkies make better long-term economic sense if you asked him.  I have not followed your postings on your trench layout that you posted in the fall, but they were initially very complicated and I wondered about the logistics of machinery access, etc.   I hope you've tapped some of the professional brainpower here and gotten some feedback on your plans.  Post you plans or paste a link to your latest discussion thread.

Posted By jonr on 10 May 2011 08:39 AM
Maybe someday someone will do two supposedly equivalent loops in different ways (say slinky and straight) and post comparison results here.

Posted By pachai on 10 May 2011 12:15 AM
I'll try to attach a quick sketch I just did - somewhat based on discussions here.

The lot is 52' x 104'
The driveway is 104' x 9'

When they were installing the foundation wall, I had them
embed 2 "NDS Sewer pipes"  6" Diam x 2' long, below the frost line.
This way, I can do the geo later without harming the waterproofing.

The contractor is planning to replace the driveway soon.
I had in mind to ask him to bid out a trench 4' wide x 104' long x 8' deep,
and also a horizontal trench 50' x 4' x 8' deep.
(The NO DIG zone is the root system for a huge tree)

My thought based on the 6 pipes was to make 3 loops
up to the top of the lot, then down to the bottom,
then back to the house.   That's 6*100
and do it again on the horizontal.

But maybe I can do it with slinkies?

Is it possible to make a U turn (or a 4' Diam turn) with
a vertical slinky?   Could I put 2 vertical slinkies and 1 flat
in a single 4' wide trench?

BTW, my enhanced plan was to monitor loop temperatures
and have the computer choose the loops that can afford to
give the most heat.   I may also put solar themal collectors.

I live in NJ - 07055.
The living part of the house will be 2000 SF.
The attic will (by summer's end)  be sealed with closed cell insulation.
The walls will be R15 but I'll be spraying some foam there also.
I have a thermal imaging camera to observe leakage.

Thanks for any suggestions.
Seth

Seth,

You have some serious logistical challenges, not the least of which is you have very little yard area available.  Your driveway appears to be about 9.5' wide to the property line.  Only if you dug maybe an 18" wide trench 12" from the property line and 6' deep would you be able to place the soil next to the trench.  While there are some strategies to dig bigger trenches in this section if you move the soil elsewhere, your bigger problem is simply getting enough length of trenches.  It's advisable that you make all your loops approximately the same length so that you can get the same flow rate through each, so from what I can see you need to run one loop(s) toward the back of your house and another to the front and turn into your front yard, both starting from the basement access point.  At most, those two trenches would be 160 feet each, and I can't see you having enough of a heat sink to draw upon in any scenario, but you'll have to get the feedback of the professionals on this site.    

Does your driveway need replacement?  Why go through all the expense of demoing and hauling the concrete and pouring a new slab.  That alone would cost you at least $5k, so why not put that money towards a drilling vertical well?