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ASSEMBLY INSTRUCTIONS FV ENERGO

FV ENERGEO is a complete system of key elements for utilization of geothermal energy by means of depth wells and surface ground collectors. Geothermal energy is one of the most environmental-friendly and virtually inexhaustible heat resources and thus represents an attractive solution with an interesting returnability. The installation design of the geothermal systems with heat pumps can be carried out exclusively by authorized persons and firms. Drilling of depth wells is addressed by specific legal codes for mining and in most countries it falls under the jurisdiction of the mining office.

SURFACE COLLECTORS

A system of ground surface collectors is the most effective option when considering the choice of the type of installation of a heat pump. Acquisition costs
are comparable to the air-water system, the advantage being a higher effectivity (COP) and longer lifespan of the compressor. In the case of surface collectors, the energy is obtained by means of piping laid horizontally below the ground, usually in a 1.2-1.5m deep excavation, or alternatively in a groove dug by a trencher. For collectors, a piping of d32 to d40 is typically used, rarely also d25. In the piping system circulates an antifreeze liquid (alcohol, glycerine, glycol) which is diluted with water to the required ZÁMRZNOST. In the heat pump it passes its heat to the cooling agent, which then gains it back by its heating under the ground. The temperature of the ground in the depths up to 5m is influenced by outside conditions (rain, snow, wind) and it also differs according to the season.

After the collectors are placed, it is not possible to carry out any other construction in this location. According to the bedrock, surface collectors must be constructed with a piping FV ENERGEO HDPE 100R C in pressure lines PN10, PN12.5 and PN16. This material enables laying without sand bed and carrying out of backfill using directly the dug material including aggregate up to the size of 200mm.

CONNECTING

For connecting of individual pipes, mainly electro pipe fittings are used, rarely mechanical clamp links. When using the electro pipe fittings, a completely homogeneous link arises, therefore in the system FV ENERGEO we use high-quality electro pipe fittings Georg Fisher.

The work must be carried out by workers with welding license for plastic welding. It is not possible to weld polyethylene with polypropylene, but at the same time we warn about mutual welding of pipes and pipe fittings from branched (LDPE, rPE) and linear polyethylene. Welding of these relatively hardly distinguishable materials (LDPE has thicker walls for the same pressure) cannot be by any meanscarried out in practice. If it is necessary to connect these two materials, in case of any doubt about the origin of particular pipes, you are better advised to use mechanical clamp links.

BACKBONE PIPEAGE

Connection of a distributor / collector with thermal pumps is carried out by means of backbone pipeage. Backbone pipeage is made by a polyethylene pipingof a higher diameter FV ENERGEO HDPE or FV ENERGEO HDPE-RC. The diameter o f the piping is determined according to its length and a flow rate of the antifreeze liquid. It is necessary to lay the backbone pipeage of the HDPE pipes in the sand bed.

INSULATION OF A PRIMARY CIRCUIT

All kinds of pipes, be it backbone pipeage or piping leading directly to the wells in the case of the surface collector, need to be insulated, beginning at 2 m away
from the object. All pipes inside the object also need to be insulated, so as to avoid potential water condensation at the distributions. It is only possible to insulate the primary circuit with a suitable rubber insulation, not with an insulation of the PE material and the like. It is necessary to protect the piping insulated by a rubber insulation outside the object by a cable duct and provide it with a gasket preventing the water intrusion into the gasket. Principles of correct instalation of ground surface collectors:

  • Right proportioning – the most important protection against freezing of the collector
  • Drop pipe for easy bleeding at the highest point
  • Compliance with safe pitches of piping – at least 60-100cm according to the piping diameter, optimally 1m.
  • Laying of collectors at least 0.7-1m away from the water pipe / sewerage, in case of crossing with engineering networks insulating of the piping.

GEOTHERMAL WELLS

In the case of geothermal wells the energy is obtained by means of geothermal ground probes. It is a closed system, where wells in the depth between 70m and 300m are machined by the piping FV ENERGEO HDPE-RC. At the end of the piping, there is a returnable U bend. Two basic ways of machining are used:

  • One-circuit probes with pipes 2x25, 2x32 or 2x40mm
  • Two-circuit probes with pipes 4x32mm.

The most common well depth is 150m. The temperature at the depth of 20m under ground is approximately 10°C and rises by 1°C for every 30m – it is not influenced by momentary weather conditions or outside temperature at the surface, nevertheless it differs at the beginning and at the end of the season. At the depth of 150m, there is virtually stable temperature of 15°C, which is sufficient for the needful thermal gain. The higher thermal gain at greater depths is compensated by the significant growth of installation costs (well and machining). There is an antifreeze mixture (alcohol, glycerine, glycol), which is diluted with water to the required zámrznost. When proportioning the depth of the wells, we recommend expecting the profitability up to 50W/m for heating and up to the load of about 2400 hours yearly including the TUV heating. The profitability should be verified appropriate ly by a special test.

REDUCTION IN THE NUMBER OF BRANCHES (Y-PIECE)

Y-piece is a special pipe fitting for associating of two circuit geothermal ground probes in one circuit (32-32-40, or 40-40-50). By their use the number of connecting pipings leading from the well to the system of the distributor / collector and also the number of the outputs of the distributor / collector itself is reduced. Y-piece CANNOT be replaced by a classical T-piece because of the prevention of a strong pressure loss in the whole system! When using the reduction it isnecessary to abide by an even division of the flow of the liquid into both loops of the g eothermal well.

Principles of correct implementation of geothermal wells:

  • Correct proportioning of the depth and the number of wells (wrong proportioning can lead to a freezing of the well)
  • Compliance with safe distances between the geothermal wells according to the depth of the well – 10% from the total well depth recommended
  • Using of the FVENERGEOHDPE-RC probes
  • Using services of verified drilling companies (a necessity of the implementation of the works with an approval of corresponding authorities)
  • Compliance with basic conditions and not jeopardizing current systems of drilled / dug water wells in the vicinity (injecting of wells – isolation of particular water wells)

LAYING OF A SAND BED

Laying in an open excavation, where sand is used for underlaying and surrounding of the piping, is one of the oldest ways of layings for PE piping. If we did not lay the older types of PE pipings (PE63, PE80 and PE100) which do not possess improved resistance to mechanical stress in sand, their expected lifespan would reduced more than five times. Thanks to the sand underlaying and surrounding, which protects the piping, this method of laying is one of the laying methods with a low risk of damage.

LAYING

In the case of the piping from HDPE-RC, its laying and backfill can be carried out without the sand bed, using the directly excavated soil including the aggregate up to 200mm. In the case of HDPE pipings it is necessary to respect the character of the bedrock. If the piping route occurs in areas with soils of the minability class
I.to IV. (according to CSN736133:2010), we can also use the directly excavated soil for the laying. An exact determination of the minability class can only be determined by a geological research, that is usually a part of each project preparation. Earthwork during the piping laying must not influence its ovality. Material
for surrounding and backfill need to be compactable enough. Piping is laid onto the even and paved bottom of a groove. The surrounding is carried out layer by layer and is compacted. If the route of the piping is located in areas with soils of the minability classes of V. to VII. or where the occurrance of these soils cannot be disproved, it is necessary to duly lay the piping in a sand bed.

CONNECTING

For connecting of individual pipings, mainly electro pipe fittings, and rarely mechanical clamp links are used. When electro pipe fittings are used, a completely
homogenious link arises, therefore in the FV ENERGEO system we use high-quality electro pipe fittings Georg Fisher.  

WELDING

For connecting the FV ENERGEO HDPE and HDPE-RC pipes with pipe fittings or butt welding can be used, polyfusion or with the use of electro pipe fittings
which we recommend for the FV ENERGEO system. Apart from a problem-free connecting right in the field, electro pipe fittings also enable assembling of the
whole piping thanks to integrated clamps. Welding work must be carried out by workers with welding licence for plastic
welding. It is unacceptable to weld polyethylene with polypropylene and to weld pipings and pipe fittings of branched (LDPE, rPE) and linear (HDPE, HDPE-RC) polyethylene. If it is necessary to connect these two materials, mechanical clamp links must be used. The most important operations for achieving a high-quality weld are:

  • cleansing of the ends of the pipes or pipe fittings of mechanical dirt
  • perpendicular trimming (planing) of the ends of the pipes, so that the maximum distance between the contacted pipes is 0.5 mm.
  • check of mutual overrunning of the pipings which must not exceed 1/10 of the wall thickness (be careful about pipings from different pressure lines!)
  • in the case of polyfusion and electro welding removing of an oxidizable layer of plastic with subsequent cleansing with a suitable degreasing and cleansing agent. Cleansing is carried out immediately before welding and cleansed surfaces must not be contaminated by a touch of a hand.
  • A place of butt welding or polyfusion welding should be protected against weather conditions.

Be careful about welding at low temperatures – allowed minimum temperatures at which welding is still possible, are determined by the properties of welding machines or electro pipe fittings. In the strong wind, in the case of butt welding or polyfusion welding, it is necessary to check not only the right temperature settings of the welding agents, but also the actual agent temperature. Welding temperature for PE butt welding is 200–220°C, for polyfusion welding 250–270°C. It is important to comply with the time course of particular operations including the time for weld cooling, during which the weld cannot be burdened mechanically. In this context we refer to the instructions of the manufacturers of particular welding devices and primarily to the compulsory trainings.

MECHANICAL CONNECTING

Mechanical clamp links enable connecting of combinations of different materials
and also enable the use of slightly oval pipings which can be formed by pipe
fittings. Links can be metal or plastic. When carried out properly, the link has
the same or higher breaking strain than the connected piping itself. Connecting
using flanges (edge bearers).

MANIPULATION WITH THE PIPING, MECHANICAL STRAIN AND CHANGE IN THE DIRECTION OF THE PIPING (BENDING)

It is not allowed to carry out heat shaping of the pipes at the construction site. However, PE elasticity allows for a change of direction or copying the terrain by producing arcs with a diameter R, which should be, according to the temperature (independently of the piping pressure line):

  • 20°C.....20 x D
  • 10°C .....35 x D
  • 0°C.......50 x D

where D is the outer piping diameter. A properly carried out excavation can therefore mean savings of the material and time. For more significant changes in the direction, particular pipe fittings need to be used.Spools with pipings must be protected against mechanical damage. In a case of visible damage of the outer layer (its cutting or rubbing) it is necessary to cut  out the particular piping and connect the ends with a suitable pipe fitting. Pipes can only be unwinded the opposite way than they have been winded during their production. Spiral unwinding, when the wall of the piping is strained torsionally and when there is a danger of „breaking“ the piping, is strictly forbidden. Fittings and cast iron pipe fittings need to be built in in such a way that their own mass or forces needed for their operation would not produce forces that were not taken into account when designing. We recommend fixing the fittings by a „firm point“, e.g. using a concrete block and so on.