PE Floor Heating Composite Plastic Pipe Complete Extrusion Machine For Indoor Geothermal Heating Piping Layout

A PE floor heating composite plastic pipe complete extrusion machine is a purpose built production line that converts polyethylene resins, an oxygen barrier medium and, in composite variants, an aluminium tape into coiled pipe rated for continuous circulation of hot water beneath a floor screed. It is not simply a small diameter water pipe line with a coiler bolted on the end. Underfloor heating pipe must survive fifty years of thermal cycling at elevated temperature and internal pressure, must be flexible enough to be bent around a 5 D radius by an installer kneeling on a construction site, must not allow atmospheric oxygen to diffuse through the wall and corrode the steel components of the heating circuit, and must hold its dimensional tolerance tightly enough that compression fittings and press fittings seal reliably every time. Every one of those requirements traces back to a specific decision in the extrusion line: which resin, which layer structure, which die, how the aluminium is welded, how the vacuum tank is staged, how the haul-off is tensioned, and how the coiler releases the pipe.

This guide walks through the complete machine and the complete decision chain behind it, from resin selection through to the indoor geothermal heating piping layout that the finished pipe will eventually serve. Faygo, a Wanplas factory, has built pipe extrusion lines for twenty-two years from its Zhangjiagang facility, and the practical guidance here reflects what actually determines whether a floor heating pipe line hits its rated output with first pass yield above 97 percent, or whether it spends its life fighting layer thickness drift and coil memory complaints. Throughout 2026, demand for radiant floor heating continues to grow across renovation markets in Europe, retrofit projects in northern China, and new residential construction in Korea and eastern Europe, and buyers are increasingly specifying barrier pipe as the default rather than as an upgrade.

Why Floor Heating Pipe Extrusion Is Its Own Discipline

Floor heating pipe sits at the intersection of three engineering constraints that rarely appear together in other pipe products: long term hydrostatic strength at elevated temperature, extreme flexibility with controlled elastic recovery, and a gas barrier requirement measured in milligrams per litre per day. A cold water distribution pipe needs only the first. A garden hose needs only the second. A fuel line needs only the third. Underfloor heating pipe needs all three simultaneously, and the extrusion line has to deliver them without compromise across every metre of a 600 m coil.

The first constraint is thermal. A radiant floor circuit typically operates with a flow temperature of 35 to 45 degrees Celsius and a return temperature 5 to 10 K lower, which sounds gentle. But the design standard requires the pipe to tolerate malfunction temperatures of up to 100 degrees Celsius for limited cumulative hours, and the fifty year design life is calculated against a temperature profile that includes those excursions. Standard PE 100 would fail this profile. The material must be either a raised temperature resistance polyethylene, designated PE-RT, or a crosslinked polyethylene, designated PE-X, or a metal composite structure that shares the hoop stress with an aluminium core.

The second constraint is mechanical handling. The pipe is supplied in coils of 100, 200, 400 or 600 m, and an installer clips it to an insulation panel in serpentine or spiral loops with bend radii as tight as five times the outside diameter. If the pipe has excessive coil memory it springs out of the clips. If it is over-annealed it kinks. If the residual stress from the cooling line is asymmetric around the circumference it will curl in one plane and fight the installer. The extrusion line, specifically the cooling gradient and the haul-off tension profile, determines this behaviour far more than the resin datasheet does.

The third constraint is oxygen. Atmospheric oxygen diffuses through the wall of an unmodified polyethylene pipe at a rate that is entirely irrelevant for a cold water line but destructive in a closed heating circuit, where it corrodes cast iron boiler sections, steel manifolds, pump housings and radiator bodies, producing magnetite sludge that blocks the circuit. The reference limit is set by DIN 4726, which permits no more than 0.1 mg of oxygen per litre of circuit water per day at 40 degrees Celsius. Meeting it requires either an EVOH coextruded barrier or an aluminium layer, and it requires the extrusion line to deposit that barrier evenly.

Floor heating pipe is judged on three axes at once: fifty year hydrostatic strength at elevated temperature, coilability with controlled recovery, and oxygen permeation below 0.1 mg per litre per day. A production line that optimises for any one of these in isolation will fail the other two.

Material Systems: PE-RT, PE-X and Aluminium Composite Structures

Material choice drives the entire line configuration, so it is the first decision a buyer must fix. Four families dominate the global floor heating market, and each carries a different capital and process footprint.

PE-RT Type I and Type II

PE-RT is a medium density polyethylene copolymer whose elevated temperature performance comes from a controlled distribution of short chain branches that create a dense network of tie molecules between crystalline lamellae. Because it is not crosslinked, it remains a genuine thermoplastic: it can be heat fused, socket welded, butt welded and electrofusion joined, and production scrap can be reground and reintroduced at modest ratios. Type I is based on hexene or butene comonomer and typically carries a density of 0.933 to 0.938 g/cm3 with a melt flow rate around 0.5 to 0.9 g per 10 min at 190 degrees Celsius and 2.16 kg. Type II uses octene comonomer with a bimodal molecular weight distribution, offers a higher long term hydrostatic strength curve, and permits thinner walls for the same class rating.

From a machine perspective PE-RT is the friendliest. Melt temperature sits at 200 to 225 degrees Celsius, the melt is stable, the die swells predictably, and the line runs continuously with no downstream chemistry. This is the reason PE-RT has taken a growing share of the floor heating market over the past decade and why most new lines Faygo ships for this application are PE-RT configured, often with a PE-X upgrade path reserved.

PE-X: PEXa, PEXb and PEXc

Crosslinked polyethylene converts the thermoplastic into a thermoset network, dramatically improving creep resistance, thermal memory and resistance to slow crack growth. The three routes differ in chemistry and in what they demand from the line.

• PEXa (peroxide route) crosslinks in the melt inside a heated ram extruder or a specialised long die at 200 to 240 degrees Celsius. It gives the highest and most uniform crosslink distribution, typically 75 to 89 percent gel content, and produces excellent thermal memory, meaning kinks can be repaired with a heat gun. Line speeds are the lowest of the three, commonly 3 to 8 m/min for 16 mm, and the capital requirement is Premium.
• PEXb (silane route) grafts vinyl silane onto the polymer during extrusion, then crosslinks in a hot water bath or steam sauna at 80 to 95 degrees Celsius over 4 to 16 hours, reaching 65 to 75 percent gel content. Extrusion speeds are close to conventional PE, but a curing hall and coil handling logistics are required. Capital requirement is High.
• PEXc (electron beam route) extrudes conventional PE and crosslinks the finished pipe by passing it under an electron accelerator, reaching 60 to 75 percent gel content. The extruder is standard, but the accelerator, its concrete shielding and its licensing dominate the investment. Capital requirement is Very High.

PERT-AL-PERT and PEX-AL-PEX Multilayer Metal Composite

The aluminium composite structure sandwiches a longitudinally welded aluminium tape between an inner and an outer polyethylene layer, bonded with a reactive adhesive tie layer. A typical 1620 pipe has an inner PE-RT layer of 1.0 to 1.2 mm, an adhesive layer of 0.03 to 0.06 mm, an aluminium tape of 0.18 to 0.30 mm, a second adhesive layer, and an outer PE-RT layer of 0.35 to 0.45 mm. The aluminium provides three benefits at once: it is an absolute oxygen barrier, it reduces the linear thermal expansion coefficient from roughly 1.8 by 10 to the minus 4 per K for plain PE-RT to about 0.25 by 10 to the minus 4 per K, and it gives the pipe plastic bending memory so it stays where the installer bends it without clips.

EVOH Oxygen Barrier Layers and Oxygen Permeation Control

Ethylene vinyl alcohol copolymer is the standard oxygen barrier for non-metallic floor heating pipe because its oxygen transmission rate is three to four orders of magnitude lower than polyethylene at the same thickness. In a five layer barrier pipe the structure runs PE-RT core, adhesive tie, EVOH, adhesive tie, PE-RT skin, with the EVOH placed near the outer surface where the water activity is lowest.

The critical process reality is that EVOH is hygroscopic and its barrier performance collapses as it absorbs moisture. Grades with 32 mol percent ethylene content give the best barrier but are the hardest to process and the most moisture sensitive. Grades with 38 to 44 mol percent ethylene are easier to extrude, more thermally stable and more tolerant of the coextrusion interface, at the cost of somewhat higher permeation. For floor heating, 38 mol percent grades are the common compromise. Resin must be dried to below 0.05 percent moisture, typically 4 to 6 hours at 80 to 85 degrees Celsius in a desiccant dryer with a dew point at or below minus 40 degrees Celsius.

The barrier extruder itself is small, usually a 20 to 30 mm single screw with a length to diameter ratio of 25 to 30 to 1, running at 190 to 215 degrees Celsius. Because the EVOH stream is only 3 to 6 percent of total throughput, a gear pump or a precision metering screw drive is strongly recommended. Without metering, a one percent variation in barrier extruder output produces a visible thickness swing in a layer that is only 0.10 mm thick to begin with, and thin spots are where oxygen gets through.

Interpreting the DIN 4726 Requirement

DIN 4726 sets the oxygen permeation limit for pipes used in closed hot water heating systems at no more than 0.1 mg per litre per day measured at 40 degrees Celsius, with a tighter figure often quoted at 80 degrees Celsius for high temperature circuits. A well made five layer PE-RT pipe with a 0.10 to 0.12 mm EVOH layer commonly measures in the range of 0.005 to 0.02 mg per litre per day at 40 degrees Celsius, giving a healthy margin. An aluminium composite pipe measures effectively zero within the resolution of the test.

The failure modes to guard against are worth naming explicitly. Interfacial delamination between EVOH and the tie layer creates a channel. Excessive shear heating degrades EVOH into gels that appear as hard specks and as local thin spots. Insufficient drying causes bubbles and streaking. And a die design that starves one side of the annulus produces a barrier that is 0.15 mm thick at three o’clock and 0.04 mm at nine o’clock, which passes an average thickness check but fails a real permeation test.

Line Architecture of a Complete Floor Heating Pipe Extrusion Machine

A complete floor heating pipe extrusion machine is a sequence of ten functional stations, each with a defined handover to the next. Understanding the handover points is the key to specifying the line, because most production problems occur at an interface rather than inside a single machine.

1. Material handling and drying. Central vacuum loaders feed the main hopper. PE-RT itself needs only light drying, typically 2 to 3 hours at 70 to 80 degrees Celsius, but EVOH and any adhesive tie resin require dedicated desiccant dryers. Gravimetric dosing units meter masterbatch at 1 to 3 percent with a batch accuracy inside plus or minus 0.5 percent.
2. Main extruder. For 16 to 32 mm floor heating pipe the workhorse is a 45 mm or 50 mm single screw with a 30 to 33 to 1 length to diameter ratio, a barrier screw with a Maddock or spiral mixing section, and an AC or permanent magnet synchronous drive of 37 to 55 kW. Grooved feed bushings with independent temperature control lift specific output to 12 to 16 kg per hour per rpm-independent unit and stabilise output against back pressure swings.
3. Barrier and tie layer extruders. Two small satellite extruders, commonly 20 mm and 25 mm, mounted on a common frame, feeding the coextrusion die through heated adapters with independently controlled zones.
4. Melt filtration and pressure control. A screen changer with 80 to 150 mesh packs, plus a melt pressure transducer loop that either trims screw speed or drives a gear pump.
5. Multilayer coextrusion die head. Spiral mandrel or overlapping layer design, described in detail below.
6. Vacuum calibration tank. Sizing sleeve, vacuum control, first stage cooling.
7. Spray cooling tanks. One to three additional tanks with staged water temperature.
8. Ultrasonic wall thickness measurement and laser diameter gauge. Closed loop feedback to haul-off speed and vacuum level.
9. Caterpillar haul-off. Two, three or four track, servo driven, with programmable clamping pressure.
10. Printing, cutting and coiling. Inkjet or hot foil marking, planetary or guillotine cutter, and an automatic dual station coiler with strapping.

Extruder Sizing and Output Mapping

The single most common specification error is oversizing the main extruder in the belief that headroom is free. It is not. An oversized screw running at low rpm gives poor melt homogeneity, longer residence time and greater risk of thermal degradation in the EVOH stream if the melt streams are temperature mismatched. Match the extruder to the actual product mix, and add a second line rather than a bigger screw if volume grows.

Twin and Quad Strand Configurations

Because 16 by 2.0 mm pipe weighs only about 0.09 kg per metre, a single strand line is often limited by the maximum haul-off speed and coiler cycle time rather than by extruder capacity. Twin strand and quad strand dies split the melt into two or four annular channels, feeding parallel calibration sleeves, cooling tanks, haul-offs and coilers. Quad strand PE-RT lines at 30 m/min per strand deliver an effective 120 m/min of finished pipe from a single extruder, which transforms the economics for high volume producers. The engineering price is die balancing: melt distribution between strands must be held inside two percent, otherwise the strands drift in wall thickness and the operators end up trimming the fast strand by hand.

Multilayer Coextrusion Dies and Layer Thickness Uniformity

The coextrusion die is where a floor heating pipe line either earns its money or loses it. In a five layer structure the die must accept three melt streams at different viscosities and temperatures, distribute each into a uniform annulus, combine them without interfacial instability, and deliver a concentric tube whose barrier layer varies by no more than about 12 percent around the circumference.

Spiral Mandrel Distribution

The spiral mandrel is the standard distribution geometry for each layer. Melt enters through four to eight ports, flows into helical grooves machined into a mandrel, and progressively leaks over the land between grooves until the flow is fully circumferentially uniform. Design variables are the number of spirals, the spiral pitch, the groove depth taper and the gap taper. For an EVOH layer the design must contend with a melt stream that is far smaller and often more viscous than the polyethylene streams, so the spiral channel is proportionally deeper and the relaxation length longer to avoid weld line witness marks.

Layer Combination and Interfacial Stability

Layers combine either inside the die, in a stacked design, or at the die exit in an overlapping design. Stacked combination gives better bonding and a shorter overall die but requires all melt streams to be thermally compatible, since they share residence time in the combining zone. If PE-RT is running at 225 degrees Celsius and EVOH at 205, the combining zone must be set between the two, typically 210 to 215 degrees Celsius, with the EVOH adapter insulated from the main body.

Interfacial instability, which appears as a wavy or zebra-striped barrier layer, occurs when the viscosity ratio between adjacent layers exceeds roughly 3 to 1 at the shear rate in the combining zone, or when the interfacial shear stress exceeds a critical value. The remedies are to adjust melt temperatures to bring viscosities closer, to increase the combining zone gap so shear stress drops, or to change the tie layer grade. Faygo builds its floor heating dies with individually zoned adapters precisely so that this viscosity matching can be done at the control panel rather than by swapping hardware.

Concentricity and the Wall Thickness Budget

Concentricity is adjusted by radial bolts on the die ring, and modern lines increasingly use automatic centring based on feedback from an ultrasonic measuring head. The wall thickness budget is worth spelling out for a 16 by 2.0 mm pipe with a minus zero plus 0.3 mm wall tolerance. Nominal wall is 2.0 mm. Circumferential eccentricity from the die consumes 0.10 to 0.20 mm of the budget. Longitudinal drift from output and haul-off variation consumes 0.05 to 0.10 mm. Sag in the melt before calibration consumes 0.02 to 0.05 mm. The remainder is the safety margin, and the whole exercise explains why die quality is the single item on which a floor heating pipe line should never be value engineered.

Aluminium Tape Forming: Butt Welding Versus Overlap Welding

For PERT-AL-PERT and PEX-AL-PEX production, the aluminium forming station is inserted between the inner layer extrusion and the outer layer extrusion. A coil of aluminium strip, typically grade 1050 or 1060 in the O temper, is unwound, edge trimmed, progressively roll formed around the extruded inner pipe, and welded along its longitudinal seam. Two welding philosophies compete, and the choice defines the product class.

Longitudinal Butt Welding

In butt welding the aluminium edges are brought together edge to edge with no overlap and fused, almost always by tungsten inert gas welding under argon shielding, sometimes by laser. The result is a continuous aluminium cylinder of uniform thickness with no step. Advantages are a constant wall section, a perfectly round pipe, better bending performance with no hinge line, and the ability to use thicker aluminium, 0.18 to 0.60 mm, for larger diameters up to 63 mm and beyond. The disadvantages are process sensitivity: the edge preparation must be clean and burr free, the gap must be held within roughly 0.05 mm, welding speed is limited to about 8 to 18 m/min, and the weld must be tracked by a seam follower.

Longitudinal Overlap Welding

In overlap welding the aluminium strip is formed with a 3 to 8 mm overlap and joined by ultrasonic welding or by adhesive bonding under pressure. It is simpler, faster, up to 25 to 30 m/min, and tolerant of edge quality. The penalty is a thickened seam that creates a local stiffness discontinuity, slightly reduced roundness, and a small risk that the overlap opens under repeated bending. Overlap construction is common in small diameter, thin aluminium, lower cost pipe for markets where the pipe is embedded in screed and never re-bent.

Adhesive Layer Management

Whichever welding route is used, the bond between aluminium and polyethylene decides whether the pipe survives thermal cycling. A maleic anhydride grafted polyethylene adhesive is coextruded onto the inner pipe surface before the aluminium closes around it, and applied again on the aluminium outer surface before the outer skin is extruded. Peel strength between layers should exceed 60 N per 25 mm width, and thermal cycle testing between 20 and 95 degrees Celsius for 5000 cycles should show no delamination. Underdosed adhesive gives a pipe that looks perfect on day one and blisters after a heating season.

Vacuum Calibration, Spray Cooling and In-Line Wall Thickness Control

Once the melt leaves the die it is a soft annular tube whose final geometry is fixed by the calibration and cooling section. This is where dimensional accuracy is actually created.

Vacuum Calibration Tank

The extrudate enters a stainless steel sizing sleeve whose bore is 1.5 to 3 percent larger than the target outside diameter, allowing for shrinkage. The tank is held under partial vacuum, commonly minus 20 to minus 60 kPa relative to atmosphere for small floor heating pipe, which pulls the tube against the sleeve wall. Sleeve design matters: slot patterns and bore finish determine whether a water film forms cleanly between pipe and sleeve. A rough or scored sleeve leaves drag marks along the pipe surface, and for a product sold on appearance and printed with metre marks, that is a reject.

Vacuum stability is directly a dimensional variable. A swing of 3 kPa in tank vacuum moves the outside diameter of 16 mm pipe by roughly 0.03 to 0.05 mm. Faygo specifies a closed loop vacuum controller with a proportional bleed valve holding the setpoint inside plus or minus 1 kPa, and separates the vacuum circuit from the water circulation circuit so that pump cavitation does not translate into diameter ripple.

Staged Spray Cooling

Rapid quenching of the outer surface while the inner wall is still molten builds a steep thermal gradient and locks in residual stress, which is precisely what causes coil memory problems later. Good practice is a staged temperature profile: the first tank at 18 to 22 degrees Celsius to set the skin and stabilise the diameter, subsequent tanks stepping down to 12 to 16 degrees Celsius. Spray nozzles rather than full immersion give better heat transfer per litre of water and allow the pipe to be inspected visually along the tank.

Total cooling length is driven by wall thickness and line speed. A practical rule for PE-RT is roughly 0.8 to 1.2 m of cooling per m/min of line speed for 2.0 mm wall, meaning a 30 m/min line needs 24 to 36 m of combined vacuum and spray tank. Underlength cooling shows up as pipe that is still warm at the haul-off, deforms under the caterpillar tracks and arrives at the coiler soft enough to flatten in the coil.

Ultrasonic Thickness Measurement and Closed Loop Control

An ultrasonic measuring head with four, six or eight transducers immersed in a water coupling chamber measures wall thickness continuously at multiple circumferential positions with a resolution around 0.005 mm. For multilayer pipe, high frequency heads can resolve individual layer thickness including the EVOH barrier, using the acoustic impedance mismatch at each interface. Combined with a laser diameter gauge, usually a dual axis or triple axis scanning gauge with 0.001 mm resolution, the system closes two loops:

• Diameter loop: laser gauge feedback trims vacuum setpoint and haul-off speed to hold outside diameter.
• Wall loop: ultrasonic feedback trims extruder screw speed relative to haul-off speed to hold minimum wall, and flags eccentricity for die centring correction.

The economic argument for closed loop control is simple and does not require quoting any figure. Without it, operators run a safety margin of 5 to 8 percent extra wall thickness to guarantee that the minimum wall never dips below tolerance. With it, that margin drops to 2 to 3 percent. On a line running continuously, that resin saving is the largest single lever on operating cost, and it is why Faygo positions the measurement package as a core item rather than an option on floor heating configurations.

Haul-Off, Cutting and Coiling Systems

The downstream handling section defines the pipe’s behaviour in the installer’s hands, which is what the end customer actually experiences.

Caterpillar Haul-Off

Floor heating pipe lines use two track or three track caterpillar haul-offs with servo drives and closed loop speed regulation better than 0.1 percent. Speed stability is not a comfort feature: haul-off speed directly sets wall thickness, so a 1 percent speed ripple is a 1 percent wall ripple. Clamping pressure is pneumatically regulated and must be low enough not to oval the pipe, typically 0.15 to 0.35 bar of pad pressure for thin wall 16 mm product, with soft polyurethane pads shaped to the pipe profile.

Marking and Traceability

Continuous inkjet or hot foil printing applies the manufacturer identification, material designation, dimensions, class rating, standard reference, metre marks and a batch code. Metre marking accuracy should be within 0.5 percent, driven off an encoder on the haul-off rather than a timer. The batch code links the coil back to the production record: resin lot, line settings, measurement traces and hydrostatic test results.

Automatic Coiling

The coiler is a distinctly under-appreciated machine. A dual station coiler with automatic transfer lets the line run continuously: as one coil reaches its set length, a flying knife or planetary cutter severs the pipe, the leading end transfers to the second station, and the full coil is strapped and ejected while the next one winds. Key specifications include:

• Coil inside diameter of 500 to 900 mm depending on pipe size, always above five times the pipe outside diameter and typically far above it.
• Traverse winding with programmable pitch so the coil is stable and does not telescope.
• Winding tension control, generally 30 to 90 N, low enough to avoid ovalisation and stress but high enough to keep the coil tight.
• Length metering accuracy within 0.3 percent, since coils are sold by length.
• Automatic strapping at three or four points and optional stretch wrapping.

Elastic recovery, or spring-back, is the property installers complain about most. It is a function of resin, of the temperature at which the pipe is coiled, and of coil diameter. Pipe coiled warm, above roughly 30 degrees Celsius, relaxes into the coil shape and shows heavy memory. Pipe cooled to below 25 degrees Celsius before coiling shows far less. This is another reason to specify adequate cooling length rather than the minimum that will hold the diameter.

Hydrostatic Testing, ISO 1167 and ISO 10508 Class Ratings

Floor heating pipe is a pressure product with a fifty year design life, and the laboratory is as much part of the production system as the extruder. Two standards frame the qualification.

ISO 1167 Internal Pressure Resistance

ISO 1167 defines the method for determining resistance to internal pressure. Specimens are conditioned, filled with water, sealed with type A or type B end caps and pressurised in a temperature controlled bath. A typical qualification matrix for PE-RT includes a short term test at 20 degrees Celsius for one hour at a high hoop stress, a 165 hour test at 95 degrees Celsius, a 1000 hour test at 95 degrees Celsius, and extended tests running to 8760 hours to validate the extrapolated regression curve. Failures are classified as ductile or brittle, and the transition point on the log stress versus log time curve is the critical output.

For routine production control the shop floor equivalent is a bank of pressure test stations running 1 hour and 165 hour tests on samples pulled per production shift, plus a hydrostatic burst rig for incoming verification of new resin lots. A practical minimum for a single line operation is a six to twelve station bath with independent pressure regulation on each station and automatic time logging.

ISO 10508 Application Classes

ISO 10508 classifies hot and cold water installations into application classes, each defined by a service temperature profile combined with a design pressure. Understanding the class matters because it determines the wall thickness the extrusion line must produce.

Design pressures of 4, 6, 8 or 10 bar are combined with the class, giving designations such as Class 4 at 6 bar or Class 5 at 8 bar. A pipe qualified for Class 5 at 8 bar needs a thicker wall than the same pipe at Class 4 at 6 bar, which is why a manufacturer must decide the target class before finalising the die and calibration tooling. In practice most residential floor heating pipe is sold as Class 4 at 6 bar or Class 4 and 5 at 8 bar, and Faygo dimensions its floor heating tooling packages around the 1620, 1622, 2022 and 2523 series that dominate those specifications.

Sokonganing Test Methods

• Oxidative induction time. Measures remaining antioxidant. Values above 20 minutes at 200 degrees Celsius indicate adequate stabiliser reserve after processing.
• Melt flow rate change. Comparing pellet and pipe melt flow rate detects thermal degradation or crosslinking during extrusion. A change beyond 20 percent signals a process problem.
• Longitudinal reversion. Immersion at 110 degrees Celsius; reversion above 3 percent indicates excessive orientation from over-drawing.
• Gel content by solvent extraction. Mandatory for PE-X, confirming the crosslink level for the declared type.
• Oxygen permeation. Direct measurement against the DIN 4726 limit for barrier pipe.
• Thermal cycling and delamination. For aluminium composite pipe, cycling between 20 and 95 degrees Celsius with peel strength checks.

Indoor Geothermal Heating Piping Layout and System Pressure Loss

A pipe manufacturer who understands the installed system sells more pipe, because layout rules dictate which sizes, coil lengths and constructions the market actually buys. Indoor geothermal and radiant floor heating layouts follow a small set of well established patterns.

Loop Patterns

The serpentine or single meander pattern runs the pipe back and forth across the room. It is the simplest to install but produces a clear temperature gradient from supply to return, so it is usually reserved for narrow spaces such as bathrooms or for perimeter zones where the hottest section can be placed against the exterior wall.

The counterflow spiral or bifilar pattern winds supply and return pipes alongside each other in a spiral toward the centre and back out. Because a warm supply run always sits next to a cooler return run, the floor surface temperature is far more uniform, typically within 2 to 3 K across the room compared with 5 to 8 K for serpentine. The counterflow spiral is the default for living areas. Its drawback is that every turn is a 180 degree bend, which is exactly where pipe flexibility and bend radius specification matter.

The combined layout uses a tighter perimeter zone with 100 to 150 mm spacing along external walls and windows, transitioning to a wider 200 to 300 mm spacing in the occupied centre of the room.

Spacing, Output and Loop Length

Pipe spacing sets the heat output per square metre and the uniformity of the floor surface temperature. Tighter spacing means higher output and better uniformity, at the cost of more pipe and higher pressure loss.

Maximum loop length is limited by pressure drop and by the temperature drop along the circuit. Practical limits are approximately 80 to 100 m for 16 mm pipe, 100 to 120 m for 17 mm, and 120 to 150 m for 20 mm. Each loop should be a single uninterrupted length from manifold to manifold with no buried joints, which is precisely why coil lengths of 100, 120, 200, 400 and 600 m are the commercial standard. A manufacturer whose coiler cannot reliably hit those lengths within 0.3 percent will lose orders on that detail alone.

Pressure Loss Estimation

Circuit pressure loss combines straight pipe friction and the local losses at bends. For a 16 by 2.0 mm pipe with an internal diameter of 12 mm carrying water at 40 degrees Celsius, flow velocity should be kept between 0.2 and 0.5 m/s. Below 0.2 m/s air cannot be flushed from the loop; above 0.6 m/s noise and erosion become concerns. At 0.35 m/s the friction loss in that pipe is on the order of 90 to 130 Pa per metre, so a 90 m loop generates roughly 8 to 12 kPa of straight pipe loss, with the 180 degree bends of a spiral layout adding perhaps 15 to 25 percent on top. Manifold, valve and mixing group losses are added separately, and the circulator is selected against the highest loss loop with balancing valves throttling the others.

Connection Methods

Two joining families dominate the installed system, and both feed back into pipe tolerance requirements.

• Compression and press fittings. A brass body with an insert and a sleeve or ring that is deformed by a press tool. These require tight outside diameter and wall thickness control, since the seal depends on the pipe wall being compressed a precise amount between insert and sleeve. This is the dominant method for PE-RT, PE-X and aluminium composite pipe in floor heating manifolds.
• Socket fusion and butt fusion. Available only for non-crosslinked thermoplastics such as PE-RT and PP-R. Socket fusion at 250 to 270 degrees Celsius joins pipe to fitting with a permanent homogeneous weld. It is common in China and parts of Asia for PE-RT floor heating risers and distribution.

Bend radius and spring-back are the last installation variables. A plain PE-RT pipe bent to 5 D will spring back partially unless clipped, which is why installers use rail clips, staples or clip tracks every 300 to 500 mm along straights and every 150 to 250 mm around bends. Aluminium composite pipe, by contrast, holds its bend plastically and needs far fewer fixings, which is a genuine labour saving and a strong selling argument in markets where installation labour is the dominant cost element.

Configuring a Faygo Floor Heating Pipe Line: Selection Guide

Faygo, a Wanplas factory, operates from a 26,650 square metre facility in Zhangjiagang, roughly two hours from Shanghai airport, and holds thirteen national patents including eight invention patents. Its PP-R and PE-RT pipe extrusion line platform covers 16 to 160 mm for PP-R and PE pipes, with the PE-RT floor heating range concentrated in 16 to 32 mm, and its broader pipe extrusion capability spans 12 to 575 mm across PE, PP and PVC. Every line is CE and ISO certified and undergoes 72 hour continuous operation testing before shipment, which for a floor heating line means running actual pipe to actual tolerance rather than simply spinning the screw.

Step 1: Fix the Product Matrix

List every size and construction to be produced, with annual volume. A producer making only 1620 and 2022 barrier PE-RT has a very different optimum line from one who must also make 2523, 2625 and 3229. Tooling changeover time, not extruder capacity, usually decides throughput for a multi-size producer, so quick change die packages and pre-heated spare calibration sleeves deserve serious budget attention.

Step 2: Decide the Layer Structure

Three layer, five layer or aluminium composite. Three layer, with a coloured skin, no barrier, is only viable for open circuit or non-corroding systems and is a shrinking niche. Five layer with EVOH is the mainstream. Aluminium composite is a distinct product requiring the welding station and a second forming line section.

Step 3: Choose Strand Count

Single strand for flexibility and small batches. Twin strand for volume production of one or two dominant sizes. Quad strand only where a single size dominates and volume is very high, since changeover becomes progressively more painful as strand count rises.

Step 4: Specify the Measurement and Control Package

At minimum, a laser diameter gauge with closed loop control. Strongly recommended, an ultrasonic wall thickness head with layer resolution. For barrier pipe, treat the ultrasonic head as mandatory, because barrier layer thickness cannot be verified any other way without destructive sampling.

Step 5: Size the Coiling and Packing Section

Match coiler cycle time to line speed and coil length. A 30 m/min line producing 200 m coils completes a coil roughly every 6.7 minutes, which a single station coiler with manual strapping can just about handle. The same line producing 100 m coils completes one every 3.3 minutes and needs dual station automation.

It is worth noting how the floor heating line fits into the wider Wanplas portfolio. Compounding of the PE-RT masterbatch and any filled or stabilised formulation is handled by twin screw extruders from Wanplas’s Kerke factory, which integrate upstream of a Faygo pipe line where a producer wants to compound in house. Where a producer also wants to reclaim purge and start-up scrap, washing and pelletising equipment from Wanplas’s Polyretec factory closes that loop for the non-crosslinked PE-RT fraction. Across the Wanplas brand the shared commitments apply: an annual free spare parts allowance, transportation guarantee, guaranteed production capacity, and an open factory policy for pre-shipment inspection.

Commissioning, Troubleshooting and Operating Economics

Commissioning Sequence

A structured start-up prevents the most expensive category of problem, which is a line that runs but never reaches its rated tolerance. The sequence Faygo uses during 72 hour factory testing and repeats at site is: dry run all drives and verify encoder synchronisation; heat soak the die for a minimum of 90 minutes and verify every zone within 2 K of setpoint; purge with virgin PE-RT until the melt runs clear; establish a stable single layer pipe at target diameter before introducing barrier layers; introduce the tie layer, then the EVOH, adjusting the combining zone temperature until the barrier appears smooth under a cut section examination; run for at least 4 hours and record wall thickness traces; pull samples for oxygen permeation and hydrostatic testing before releasing the line to production.

Troubleshooting Matrix

Operating Cost Structure

Operating cost for a floor heating pipe line is dominated by resin, followed by electricity, then labour, then consumables and maintenance. Because resin dominates, wall thickness control is the highest leverage improvement available, ahead of any energy saving measure. Expressed as relative weight rather than absolute figures:

Preventive Maintenance Schedule

• Daily: check die zone temperatures against setpoint, inspect sizing sleeve surface, verify vacuum stability, confirm laser gauge calibration with a reference pin, drain water filters.
• Weekly: clean spray nozzles, inspect haul-off pads for wear and embedded debris, verify gravimetric dosing calibration, check aluminium welding electrode condition where fitted.
• Monthly: pull and inspect the screen pack, verify melt pressure transducer against a reference, check gearbox oil level and temperature, inspect coiler traverse mechanism.
• Quarterly: inspect screw and barrel wear at the metering section, verify screw and barrel clearance against original specification, calibrate ultrasonic head with reference standards, service the chiller.
• Annually: full die strip and polish, particularly the barrier adapter and spiral channels, gearbox oil change, complete electrical inspection, and re-verification of the pressure test bank.

Energy Efficiency Measures Worth Specifying

Specific energy consumption for a well configured PE-RT floor heating line typically falls between 0.22 and 0.32 kWh per kg of pipe, including extruder, chiller and downstream. Reaching the lower end requires several deliberate choices: permanent magnet synchronous motors instead of standard induction motors on the main extruder, ceramic band heaters with insulating jackets which cut barrel radiant losses substantially, a grooved feed section that allows the screw to run at lower rpm for the same output, variable speed drives on chiller pumps and cooling tower fans, and staged chiller setpoints so that the final tank is not chilled deeper than required. A well insulated die with removable jacket covers typically pays for itself faster than any other single energy measure because the die runs hot continuously and is usually the most exposed hot surface on the line.

Frequently Asked Questions

What is the difference between PE-RT and PE-X floor heating pipe production lines?

A PE-RT line is a conventional thermoplastic extrusion line, because PE-RT achieves elevated temperature resistance through molecular architecture rather than crosslinking. A PE-X line adds a crosslinking stage: peroxide reaction in a heated die for PEXa, silane grafting plus a hot water or steam cure for PEXb, or an electron beam accelerator for PEXc. PE-RT lines run two to five times faster, have a lower capital requirement, and produce reprocessable scrap. PE-X lines deliver higher gel content, better long term creep resistance and thermal memory, at the cost of a curing or irradiation stage and non-recyclable scrap.

How is oxygen permeation controlled in floor heating pipe?

Either by a coextruded EVOH barrier layer of roughly 0.08 to 0.15 mm or by a continuous aluminium tape in a PERT-AL-PERT structure. The reference requirement is DIN 4726, which limits permeation to no more than 0.1 mg per litre per day at 40 degrees Celsius. A correctly processed EVOH layer typically measures 0.005 to 0.02 mg per litre per day, an order of magnitude below the limit, while an aluminium layer is effectively an absolute barrier.

What line speed can a PE-RT floor heating pipe extrusion line achieve?

A single strand 16 by 2.0 mm PE-RT line typically runs at 22 to 32 m/min with output of 90 to 140 kg/h, limited in practice by cooling length and coiler cycle time rather than extruder capacity. Twin and quad strand configurations multiply linear output while sharing one extruder. Aluminium composite lines run slower, generally 8 to 18 m/min, because the tape forming and welding stations set the pace.

Why does my floor heating pipe spring out of the installer’s clips?

Excessive coil memory almost always traces to the cooling and coiling section rather than the resin. Pipe coiled while still above roughly 30 degrees Celsius relaxes into the coil geometry and retains it. Extending the cooling length, lowering the final tank temperature to 12 to 16 degrees Celsius, increasing the coil bore diameter and reducing winding tension to the 30 to 90 N range all reduce memory. Asymmetric cooling around the circumference produces the related defect of pipe that curls in one plane.

Can I run both plain and barrier pipe on the same line?

Yes. A five layer line runs three layer or single layer product simply by shutting down the satellite extruders and switching to a single layer die insert or by running the barrier channels with the same base resin. The reverse is not true: a line built without satellite extruders and a multilayer die cannot be upgraded cheaply. If barrier pipe is anywhere in the five year plan, specify the multilayer die and the satellite extruder mounting frame from the start, even if the satellites are added later.

What wall thickness tolerance should a floor heating pipe line hold?

For 16 by 2.0 mm pipe the usual product tolerance is minus zero plus 0.3 mm on wall and plus or minus 0.10 mm on outside diameter. A properly configured line with closed loop control should hold circumferential wall uniformity within plus or minus 5 percent and longitudinal variation within plus or minus 3 percent, which leaves comfortable margin and allows the average wall to be run only 2 to 3 percent above nominal instead of 5 to 8 percent.

Which is better for floor heating, butt welded or overlap welded aluminium composite pipe?

Butt welded aluminium gives a flush, uniform section with better roundness, superior repeated bending performance and the ability to use thicker aluminium for larger diameters. Overlap welded aluminium is faster to produce, more tolerant of strip edge quality and has a lower station capital requirement, but leaves a stepped seam that acts as a stiffness discontinuity. For pipe that is embedded once in screed and never re-bent, overlap is adequate. For visible runs, risers and any application involving repeated forming, butt welding is the correct choice.

How long should the cooling section be?

A practical rule for PE-RT with a 2.0 mm wall is 0.8 to 1.2 m of combined vacuum and spray cooling per m/min of line speed, so a 30 m/min line needs 24 to 36 m. Thicker walls and higher speeds push toward the upper end. Undersizing cooling is a false economy: the pipe arrives soft at the haul-off, ovals under the pads, and carries residual heat into the coil where it develops memory.

What loop spacing and length should installers use?

Spacing of 100 to 150 mm is used at perimeters and in high loss rooms, 150 to 200 mm in standard living areas, and 250 to 300 mm in low load spaces. Loop length is limited by pressure drop, with practical maxima of about 80 to 100 m for 16 mm pipe and 120 to 150 m for 20 mm. Flow velocity should stay between 0.2 and 0.5 m/s. Every loop must run uninterrupted from manifold to manifold, which is why 100, 200, 400 and 600 m coil lengths dominate commercially.

How is the barrier layer thickness verified in production?

By a high frequency ultrasonic measuring head that resolves individual layers using the acoustic impedance mismatch at each interface, supplemented by periodic destructive cross-section examination under a measuring microscope. Ultrasonic layer measurement is the only practical continuous method; a laser diameter gauge sees only the outside surface, and total wall measurement cannot distinguish a thick barrier from a thick skin.

What certifications should the line and the pipe carry?

The machine itself should carry CE marking for the European market and be built under an ISO 9001 quality system. The pipe product is qualified against ISO 10508 for application class, ISO 1167 for hydrostatic performance, DIN 4726 for oxygen permeation, and the relevant national or regional product standard for the target market. Faygo supplies lines with CE and ISO certification and 72 hour continuous operation test records as standard.

How much scrap should a well run floor heating pipe line generate?

Start-up and changeover purge plus off-specification pipe should total under 2 percent of throughput on a mature line running a stable product mix, and under 3 percent on a multi-size line with frequent changeovers. PE-RT scrap can be reground and reintroduced, typically at 5 to 15 percent for non-barrier layers, but regrind containing EVOH must be kept out of pressure-bearing layers because EVOH inclusions act as stress concentrators.

Conclusion

A PE floor heating composite plastic pipe complete extrusion machine succeeds or fails on a short list of decisions that all interact. The material family, PE-RT, PE-X or aluminium composite, sets the line architecture and the achievable class rating. The layer structure decides whether a multilayer die and satellite extruders are required, and the EVOH barrier is where oxygen permeation compliance against the DIN 4726 limit of 0.1 mg per litre per day is either achieved or lost. The die determines wall and barrier uniformity, which in turn determines how much resin has to be given away as a safety margin. The vacuum calibration and staged spray cooling section creates the dimensional accuracy and, just as importantly, the residual stress state that decides whether installers curse the coil or praise it. The haul-off, cutter and coiler determine the finished commercial product, in the coil lengths that indoor geothermal heating piping layouts actually consume. And the test laboratory, running ISO 1167 hydrostatic programmes against ISO 10508 class profiles, is what converts a length of extruded plastic into a product that can carry a fifty year design life.

For a producer entering or expanding in the floor heating market, the practical recommendation is straightforward. Start with a five layer PE-RT barrier line in the 16 to 32 mm range, single or twin strand depending on volume, specified with a laser diameter gauge and a layer-resolving ultrasonic wall thickness head from day one. Build the cooling section generously rather than to the minimum, invest in the die rather than around it, and choose a dual station coiler with encoder driven length metering. Reserve the aluminium composite station and the PE-X curing route as second phase expansions once the base product is qualified and selling. Faygo, a Wanplas factory with twenty-two years in pipe extrusion, thirteen national patents and CE and ISO certified equipment, configures lines on exactly this logic and validates each one with 72 hour continuous operation testing before it leaves Zhangjiagang. Producers evaluating options should bring their full size matrix, target class ratings and coil length requirements to the specification discussion, because those three inputs, more than any headline output figure, determine which configuration will actually earn its keep.