GHP Systems, Inc.'s design
engineers have years of geothermal experience and are qualified to assist with
your commercial loopfield installation.
Capabilities:
GHP Systems has
on staff a certified International Ground Source Heat Pump Association (IGSHPA)
trainer, certified GeoExchange Designer and certified Air Conditioning Contractors of
America trainer and mechanical engineer who has successfully trained and IGSHPA
certified hundreds of contractors.
Sample
of
Geothermal Loopfield
Specifications
Closed Circuit Vertical Heat Exchanger (VHE)
Description of Work
A. This design has been prepared in accordance with the
materials standards and accepted installation practices of the (IGSHPA). The loopfield contractor
shall comply with these standards and practices as well as all State and local
regulations pertaining to the installation.
B. The loopfield contractor is responsible for all aspects
involved with the complete geothermal loopfield installation. All
materials, drilling, excavation, hauling of backfill, pumping, soil compaction
and labor required shall be included in the bid price.
C. The loopfield contractor shall take note: there is
no guarantee to the loopfield contractor that the location of any existing utilities
are exactly as indicated on the plans. Some areas may require
hand digging to locate that utility. The loopfield contractor must include
in the bid price, the repair of any domestic water, electrical, communication
or any service line that may be damaged during the construction of this
project. Any offsets required to route over or
under existing lines shall
also be included in the bid price of the project.
Qualifications
A. The loopfield
contractor must have on this project a certified IGSHPA
installer. The loopfield contractor performing this work must have a minimum
of two years experience in performing underground closed circuit VHE work of this project's size or larger.
B. VHE fabricators must be heat fusion certified by an authorized high density
polyethylene (HDPE) pipe manufacturer's representative of the brand of pipe
used. Certification must include: successful completion of a written heat
fusion exam as well as demonstrating proper heat fusion techniques under the
direct supervision of the authorized HDPE pipe manufacturer's representative.
Products
A. Pipe
The pipe shall be PE3408 HDPE with a minimum cell classification of 45434C per
ASTM D3035-93 and a DR11 (160 psi) rating for u-bends and header pipe 2 inches
or smaller and a minimum of
DR15.5 (110 psi) for header pipe greater
than 2 inch in diameter. This pipe will carry a warranty of no less than
25 years.
Each pipe shall be permanently indent marked with the manufacturer's
name, nominal size, pressure rating, relevant ASTM standards, cell classification
number and date of manufacture.
All piping used for VHE will have factory hot-stamped lengths impressed on
the side of the piping indicating the length of the VHE at that
point. The length stamp shall read zero on one end and the actual VHE total length on the other end.
The VHE will have a
factory fused u-bend with pipe lengths long enough to reach grade from the
bottom of the bore so no field fusions are required below the header pit.
B. Vaults/Manifolds
The vault structure should be a composite structure of steel and concrete.
The inner shell consists of a heavy-duty steel frame and base with steel
interior walls, ceiling and floor that are specially treated with a rubberized
rust resistant coating. The outer shell of the wall and ceiling consists
of 8" thick reinforced poured concrete. The GeoVault, manufactured by
GHP Systems, Inc. is an authorized vault.
The vault is shipped from the
manufacturer preformed for concrete pour with all reinforcement rods, manifolds,
and piping secured in place. The vault is set on an 18" level base of
compacted gravel. Concrete, supplied by the contractor, is then poured
into the vault form and screeded off the top of the form. Once the
concrete cures, the outer form walls are removed and the vault is ready to fuse
on the circuit and manifold piping.
HDPE pipe, joined together with heat
fusion, should be used for all of the vault's circuit and main header
piping. This HDPE pipe is tough, non-corrosive, and leak proof. All
of the vault's circuits include valves and pressure/temperature ports for
complete isolation, pressure testing and flow balancing. Acceptable
manifolds are manufactured by GHP Systems, Inc.
C.
Fittings
Pipe fittings shall meet the requirements of ASTM D2683 (for socket
fusion fittings) or ASTM D3261 (for butt/saddle fusion fittings). Each
fitting shall be identified with the manufacturer's name, nominal size, pressure
rating, relevant ASTM standards and date of manufacturer.
D. U-bend Pipe Separators
The u-bend pipe separators used to position the u-bend pipes against the
borehole wall directly across from one another -- shall be the GeoClip brand
manufactured by GBT, Inc. These separators will be positioned every ten
feet on the u-bend pipe.
E. Bentonite Grout
The thermally enhanced bentonite grout used to seal the VHE shall
have a minimum thermal conductivity of 0.57 Btu/hr-ft°F and a minimum of 43%
solids. This grout will also have a permeability rate of less than 1X10-7cm/sec.
F. Locating Tape
Locating tape must be foil backed, two inches wide or greater, with a continuous
message printed every 36 inches or less reading: "CAUTION GEOTHERMAL
PIPELINE BURIED BELOW". The tape shall be highly resistant to
alkalis, acids, and other destructive agents found in the ground.
G. Field Location
The four outside grid bores should be surveyed after drilling is complete, but
before horizontal trenching is done.
Execution
A. Drilling
The vertical boreholes will be drilled to a depth that allows complete insertion of
the VHE to its specified depth. The maximum borehole
diameter will be six inches. If a larger diameter is required, it must be
approved by the design engineer.
B. U-bend Pipe Assembly
The u-bend pipe shall be filled with water and pressured to 100
psi to check for leaks before insertion. If necessary, an iron (sinker) bar
can be attached at the base of each u-bend to overcome
bouncy. This iron bar will have all sharp edges adequately taped to avoid
scarring and/or cutting of the polyethylene pipe. No driving rod that is
pulled out after u-bend insertion will be allowed. U-bend pipe separators (GeoClips)
will be attached at ten feet intervals to the u-bend along with the grouting
tremie as per manufacturer's recommendations. The entire u-bend pipe assembly is inserted
to the specified depth in the borehole.
C. Grouting Procedure
The VHE is to be grouted from the bottom up, in a continuous
fashion, using a one inch HDPE tremie pipe. The tremie pipe will be pulled
out during the grouting procedure maintaining the pipe's end just below grout
level within the borehole. All State regulations will be met for borehole
grouting of the VHE.
D. Heat Fusion Pipe
Joining
All underground pipe joining will be heat fused by socket, butt or saddle
(sidewall) fusion in accordance to ASTM D2610, ASTM D2683 and the manufacturer's
heat fusion specifications. The operator shall be heat fusion certified
and experienced in executing quality fusion joints.
E. Excavation and
Backfilling for Piping
The loopfield contractor shall do all excavating, backfilling, shoring, bailing
and pumping for the installation of his work and perform necessary grading to
prevent surface water from flowing into trenches or other excavations.
Sewer lines shall not be used for draining trenches. All pipe and
conduit ends shall be kept sealed and lines left clean and unobstructed during
construction. Only material suitable for backfilling shall be piled a
sufficient distance from banks of trenches to avoid overloading.
Unsuitable backfill material shall be removed as directed by the design engineer.
Sheathing and shoring shall be done as
necessary for protection of work and personnel safety. Unless otherwise
indicated, excavation shall be open cut except for short sections. The
loopfield contractor shall install
geothermal locating tape 18 inches above all horizontal/header piping.
Prior to drilling or trenching, the loopfield
contractor shall be responsible for reviewing with the general contractor the location of underground utilities. Existing utility lines
uncovered during excavation shall be protected from damage during excavation and
backfilling.
F.
Pipe Installation
The u-bend pipe ends will be sealed with fusion caps or tape prior to insertion into
the borehole. Reasonable care shall be taken to ensure that the geothermal
loopfield pipe is not crushed, kinked, or cut. Should any pipe be damaged,
the damaged section shall be cut out and the pipe reconnected by heat fusion.
The VHEs must be
connected as indicated on the plans. The header design accounts for
balanced flow as well as flushing and purging flow rates. No variations
can be made in the circuit hookup or the pipe sizes that are indicated without
approval from the design engineer. The minimum bend radius for each pipe
size shall be 25 times the nominal pipe diameter or the pipe manufacturer's
recommendations, whichever is greater. The depth of all headers and supply
and return piping is indicated on the plans and must be maintained.
Circuits will be pressure tested before
any backfilling of the header trenches is executed. The individual circuits
will be pressure tested with water at 60 psi, however, not to exceed DR 11 pipe
working pressure at bottom of the u-bend pipe.
Testing and Cleaning
A. Cleaning
During
installation, all debris, and small animals shall be kept out of the pipe. Ends of the HDPE pipe shall be sealed until the pipe is joined to
the circuits.
B. Flushing and
Purging
Each supply and return circuit shall be flushed and purged with a water velocity
of two feet per second. The lines shall be left filled with clean water and
then pressure tested. If connection to the manifold is not immediate,
piping must be capped. The loopfield contractor must coordinate with the mechanical
contractor on propylene glycol antifreeze installation. The mechanical contractor is responsible for the propylene glycol antifreeze. See
mechanical specifications for antifreeze.
Shop Drawings and
Inspection of Geothermal Loopfield
A. Before
geothermal loopfield construction begins, the loopfield contractor must submit
shop drawings to the design engineer. The shop drawings shall include all
applicable manufacturer's specifications, warranties, and material safety data
sheets for all materials used in the geothermal installation. No substitutions
will be allowed without authorization from the design engineer.
For additional information, please complete
the information request form below or contact us at:
Telephone:
605-697-7869
FAX: 605-697-9118
Postal address:
1000 N 32nd Ave, Brookings, SD 57006
Electronic mail: sales@ghpsystems.com
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