Greetings.

I'm getting ready for building of an addition on my home,

and I watched my builder working on a similar project... I
couldn't help thinking that the backhoe could open trenches for me to
bury a ground loop in.

I wonder if I can ask advice of others more
knowledgable....

I have been googling a few weeks and talking to contractors,
and all of them seem to say
"we drill, and drilling is expensive...."

I have seen a couple of designs for laying out horizontal
gound loops  on a small lot and so I did a drawing for my lot.
(silly me, can't find the thread :-)

I was wondering if anyone else has succeeded in
doing horizontal loops on 5200 SF lot?  

In my favor, I probably will redo the driveway, so
that gives me 70' for one trench.

The end of the lot is 52' across.  I have not decided definitely
to do the ground loop myself, but I have yet to get a single quote
for drilling, but I have heard the prices.  And I have heard
there can be surprises.

I live in Northern NJ.
(Hoping to run my Geo on SRECs - pending the City trimming its dead trees :-)

I put a drawing at http://pachai.net/images/Rothenberg_Coils.jpeg
or http://pachai.net/images/Rothenberg_Coils.tiff
(I couldn't Attach either kind, sorry)

My thought was the backhoe could do the backyard during digging for
the foundation, I could test loop heat loss/gain, and then IF I need
to do the driveway, we could put another loop under the driveway.  

(I drew the ground loop as a slinky, but I saw a post that said
parallel pipes 3' apart are just as good and much easier to lay :-)

In my drawing, there are 0 pipe welds outside.
I don't need to learn yet another skill that I will use once :-)
There are connectors that are rated for indoor use.

On my drawing I show the pipes that approach the building and
foundation as a line, because my thought was it would be a good idea
to insulate the pipes - so the ground doesn't freeze near the
foundation.

It looks like I should be able to put 500' of trenches in.

I am still working on getting a definite Tonnage - it sounds like 5
tons is a good idea.  The house will be 4000' in a Basement and 3
floors.

(I am researching priming the walls with Insuladd, etc.
and using 3-pane glass, even though my contractor and my architect
both think it is not worth it :-)

If weather co-operates, I would prime or paint the sheathing with
ceramic paint before insulation goes up...and prime the drywall with
ceramic as well.  

Thanks
Seth

PS - all the trenches at the back of the house
will be deeper, because there is a retaining wall
(seen in the drawing).

I am still not sure about a ground loop
going under the carport, even if
it stays 2-3' away from the walls.

Thanks
Seth

An accurate heat loss/gain calculation might save some $$. I agree, triple pane windows have a long payback. I see many options for horizontal on a lot this size. What is the soil type and is it damp? Very important to determine loop lengths. IS the ductwork sufficient for max cfm to get through it at reasonable wc values? Otherwise you will waste electricity and $$. Defeats the purpose. 1. You can forget all the calculations and just throw in some pipe and a 5 tonner and hope for the best. 2. You can hire someone to design a real system even if you want to hire the subs to install it. Good luck. I've seen these systems work flawlessly for many years (20+) once designed and installed properly. Properly mean balanced and integrated components such that all operate smoothly and efficiently together. Like a symphony! energysquid.com "Dirt Cheap Energy for Life"

Going horizontal on a 5200 SF lot for a 4000 SF home will be very very difficult.

I looked at your sketch. I'm neither a horizontal nor a northern climates expert, but I foresee problems with freezing ground, thermal interaction with the house, interference with other utility entrances.

No specific unit tonnage "is a good idea" without careful Manual J land Manual D loads.

My understanding of loop styles is that a slinky would take up the least footprint, but has more pipe compared to a straight horizontal pipe layout (please someone correct me if I am mistaken.) I also suggest getting professional help with this project, then see what you are comfortable doing yourself.

Given your lot size, large house and geologic setting you may want to consider open loop. A majority--but not all of Northern NJ has good hydrogeologic conditions for open loop with high yield wells, acceptable water quality, and a reasonable depth to the water table to allow for economic pumping. Open loops in your situation can often be installed for less than closed loop since there is less drilling involved. Installing a horizontal recharge field rather than an injection well can save in installation costs too. You may also save on the water bill if you tie into the well for irrigation. -Adam

We have squeezed slinkies in even smaller areas. A couple thoughts: You can put them further together, but ideally you want to leave enough space between them to allow water to drain through between potential ice cylinders around the pipes. 6ft on center between 3 ft slinkies should be enough. Stay away at least 2 feet from every structural wall or supply line. Depth becomes your friend when you squeeze things together. 8ft deep instead of 5 ft will increase your loop temp by about 3.5 degrees F. In addition you can put 2 slinkies in one trench vertically, if you put them them at least 8ft deep at the bottom and 4 ft apart. That way you get roughly 2 tons capacity out of each 100ft trench, or 250ft of trench for a 5 ton system. I have attached an image. This all assumes relative good ground conductivity. Nevertheless, you should get professional help if you are inexperienced with geo design and installation.

Condensed slinky and depth comments are good advice.
A standing column well might be an option in your area as well.
Joe

doc,

are those slinkies nailed to the bank of the trench?

Good observation. Not really nailed to sidewalls, but using a sturdy wire bent 180 degrees around the pipe and pushed into the clay wall every 10ft or so ensures that they do not bent during careful backfilling. The walls are also not totally straight but slightly tilted. That ensures that the side walls are not caving in (nice clay helps) and that the backfill pushes the slinkies against the walls. Performance is absolutely identical to a slinky buried flat on the ground at 6 feet. http://welserver.com/WEL0267/ If you scroll down to the "individual loops" graph. Loop 1 is a horizontal slinky at 6 feet, loop 2 is the one on the picture standing vertically in the trench at 8 feet on the bottom. There was a better performance in the 1st year, but after it compacted itself, the performance is identical. So you can get 2 tons of capacity out of one 100ft trench.

Thanks so much for everyone's help.
I have this vision that I am going to teach my builder
to install horizontal loops and he's going to start
doing it all over town.  (He would love to :-)

Here's what I came up with.
(I don't recall if I shared it here, but I changed it)

http://pachai.net/images/Rothenberg_Coils2.jpeg
There are some trees, and one line is too close to the foundation,
need to move it or insulate it to protect the house.
The thick black lines are pipes I think I need to insulate
to protect surrounding structures.

I just re-read the thread, and will
check my distances, but I think I am OK (>2 feet).

I show them on the drawing as slinkies, but I am fond
of Brint's drawing with just sharing the trench with spacers.

I may run into the not-enough-space-for dirt issue.
two solutions - a good neighbor, or let the dump truck
take it away and bring back fresh compost the
next week so I can actually grow a garden.
Question for the builder - I am sure he has provided
good fill to others.

I didn't get any estimates yet - waiting on 2 installers.

Can anyone recommend a dealer for DIY in the NJ area?

Also, I asked google about heating/cooling load, and
made a spreadsheet.   I don't recall where the figures are from,
but it says 6 Ton.    I visited someone who has multiple units
in his similarly-sized house.    Since I am not finishing
the attic immediately, maybe that would make sense for me also.

I attached the pdf and saved as an xls at
http://pachai.net/images/HVAC.xls
http://pachai.net/images/HVAC.pdf

Location: Passaic, NJ

BTW, I think I know where I want the unit...
perhaps under the stairs - where I put a square box.
There's a bathroom above it that will be altered.
Or in the corner of the existing Util Room, where
the pipe in the drawing comes in.

Thanks
Seth

PS I saw a video that showed a Manifold Pit
which allowed them to run all the loops in a star
configuration, and make all the connections
in a vault, so they don't have to be fused.
(many other reasons to do this if it is allowed).

If the horizontal is not enough pipe,
I am thinking I can add 8 "vertical" loops
of 15' inside such a pit, starting 8-10' down.
And the pit would allow me to come
back and do THAT work in the spring.

I would decommission the old furnace after this heating
season ends.

Seth
PS I think Brint mentioned having timber around in case the
tractor needs to cross an open pit.    I was thinking,
also some 2x6 in case a person needs to cross.

You need a pro to help you design loop field to ensure success.
J

I second that - this looks to be a fairly tricky, highly-constrained project - seek expert help.

>>>You need a pro to help you design loop field to ensure success.

Joe + Engineer,

Thanks for the guidance.
Does it need to be someone local
(eg, my architect spent a day measuring my house himself)
or can I hire someone who is highly praised and send
plans (pdf) and pictures, video, etc?)

I exchanged emails with someone in england who put a
manifold pit under his driveway, and the pipes radiate
from there - he is happy with his results, and it is similar
to my idea.

Thanks again.
I really don't want to miss the chance to
"draft" behind the backhoe, but I have not found
a local expert available.  Maybe they are swamped with work :-)
or not expert? :-) :-)

My good friend is a rocket scientist (really, no joke :-) and is happy to help me.
(after I program his router? :-) :-).     But he is not an HVAC expert.
Just an expert at testing and measurement and thermal transfer, etc.


PS anecdote - 15 years ago, I was in a building that had no wheelchair access.
I said, we should run a path around the side, to the high ground in the back.
Pestimists said it would not work.   Long after I had moved, this is just what they did.

Local

>>>or can I hire someone who is highly praised

Oops, I meant someone on this list,
not the guy in england, who is not an HVAC/Geo expert.

We have heating-dominated, slinky specialists here (not I). Most of us would probably be reluctant to remotely consult for cash - too many unknowns and quality control issues.

In your case you want someone who will "own" the results as well as design.
Don't forget if you use area under driveway, frost line can be lower (actually pushed down by traffic) and solar contribution can be impacted.
j

Posted By engineer on 16 Nov 2010 10:12 AM
Local

I got my first quote from someone local - $66,745.00

1 Hydron Module 4 ton 2 stage water to water heat pump (HWT046)
supplying hot and chilled water....other stuff...and three
(3) Hydron Module Airhandlers (MPH024)...

1400 feet of vertically installed ground heat exchanger
(1400’= total length, 700’= total bore length, 2 bores=350’)
each made of 1.25”HDPE SDR 11, 2 year service and maintenance.


I am still waiting to hear from other contractors
(including the person who is digging the basement ).
I want to evaluate using trenches, even in my small yard.

I'm also awaiting references, as I was surprised how
hard it was to get a bid on this - more than a month.