How to Select Factory PE-RT (EVOH) Pipes for Agricultural Greenhouse Heating Systems

To select factory PE-RT (EVOH) pipes for a greenhouse heating system, start with the heating design—not a pipe price or a nominal diameter. Confirm the required operating temperature, pressure, flow rate, pipe route, installation environment, and connection method, then check that the manufacturer’s technical documents cover those conditions. The EVOH layer provides an oxygen barrier that can help reduce oxygen diffusion into a closed hydronic system; it does not remove the need to assess system corrosion protection or verify product performance. At HTIAN, we recommend comparing complete, documented pipe systems and asking the factory to confirm suitability against your project requirements before ordering.

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Key Takeaways for Greenhouse Buyers

• Specify design temperature, working pressure, pipe dimensions, and service conditions before requesting a quotation.
• Confirm the EVOH barrier construction, location, and applicable performance documentation for the exact pipe offered.
• Match the pipe and fittings to the heating layout, installation method, water quality, and local requirements.
• Request written confirmation of product data, quality checks, packaging, lead time, and batch identification.

Step 1: Define the Greenhouse Heating Requirement

Greenhouse heating can use pipes in floor loops, under benches, along crop rows, or as part of a broader hydronic distribution network. Each arrangement creates different requirements for pipe length, heat delivery, hydraulic resistance, access, and protection from agricultural operations. Before contacting a factory, prepare a basic system brief that identifies the heat source, distribution layout, expected water conditions, and whether the pipe will be exposed, covered, or buried.

Record the design conditions

Ask the system designer to state the intended supply and return water temperatures, normal and maximum operating pressure, and required flow for each circuit. For example, a preliminary brief might list a 45°C supply temperature and a 2 bar operating pressure, but these are illustrative project inputs—not universal greenhouse specifications or a recommendation for every PE-RT pipe. Final values should come from the heating design and must remain within the pressure-temperature limits documented for the specific product.

Also record the greenhouse’s operating schedule and local environment. Seasonal temperature variation, irrigation practices, cleaning chemicals, sunlight exposure, and the possibility of mechanical damage can affect pipe placement and protection needs. If the heating system may be drained, exposed to freezing conditions, or operated with treated water, include that information in the inquiry.

Step 2: Check Whether PE-RT with EVOH Fits the System

PE-RT is a polyethylene material used in hot-water piping systems, while EVOH is an oxygen-barrier layer incorporated into some multilayer pipe constructions. In a closed hydronic circuit, limiting oxygen entry can help reduce the potential for corrosion in susceptible metal components, such as certain boilers, pumps, or fittings. The barrier is only one part of system protection: water chemistry, system design, component materials, and maintenance remain relevant.

Verify the complete pipe construction

Do not assume every pipe described as PE-RT EVOH has the same layer arrangement or barrier performance. Request a cross-section or construction description showing the PE-RT layers, EVOH layer, and any bonding layers, where applicable. Ask the manufacturer to identify which side of the pipe contains the barrier and how the product is intended to be installed and connected.

Confirm whether the offered product is designed for heating service and request the applicable technical data sheet and test or compliance documentation. Requirements differ by destination market and project specification, so ask the supplier to identify the standards or local requirements the product is claimed to meet and provide supporting documents. Do not treat a general product description or a verbal assurance as a substitute for documentation tied to the exact product and size.

Step 3: Match Dimensions and Ratings to the Design

Pipe outside diameter and wall thickness influence flow capacity, pressure capability, flexibility, and installation compatibility. The designer should size circuits using the required heat output, water flow, circuit length, and acceptable pressure loss rather than selecting a diameter based only on a nearby pipe or a supplier’s standard stock size. Confirm that fittings, manifolds, and connection tools are compatible with the chosen dimension and pipe construction.

Review pressure and temperature data together

Pressure ratings can depend on operating temperature, service life assumptions, and the product’s construction. Request the manufacturer’s pressure-temperature information for the exact pipe, not only a single maximum-pressure figure. If the project includes elevated temperatures, temperature cycling, or nonstandard operating conditions, ask the factory to confirm the limits in writing before placing an order.

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Allow the heating designer to check hydraulic performance and thermal movement for the actual layout. Long runs, tight bends, circuit balancing, and changes in support spacing can affect installation and operation. Where a circuit passes through joints, doorways, or areas exposed to equipment, specify protective sleeves or other mechanical protection as appropriate to the project.

Step 4: Assess the Installation Environment

Greenhouse conditions are not the same as a protected indoor utility room. Pipes may face sunlight, moisture, fertilizer residues, cleaning agents, foot traffic, tools, or agricultural machinery depending on their route. Ask the factory for product-specific guidance on UV exposure, chemical compatibility, minimum bend radius, support spacing, and storage; if a condition is not covered in the documentation, clarify it before installation.

Plan the layout around access and maintenance

For floor or crop-row heating, coordinate pipe spacing and circuit lengths with the heat-load calculation and the crop or growing-bed arrangement. As a layout example only, a designer might assess spacing options such as 150 mm and 300 mm to compare heat distribution and pipe quantity; neither spacing is universally correct. Use project calculations and installation requirements to set the final layout, and retain access to valves, manifolds, and service points.

Specify how pipe ends and coils should be protected during shipping and storage. Keep the pipe away from sharp edges and avoid practices that could flatten, kink, or contaminate it. Before covering or burying a circuit, follow the system designer’s inspection and pressure-test procedure and document the circuit locations for future maintenance.

Step 5: Evaluate the Factory, Not Just the Quotation

A factory quotation should identify the material description, construction, outside diameter, wall thickness, coil or straight-length format, fittings if included, and packaging. Compare offers on the same technical basis: a lower unit price may not represent the same barrier construction, product documentation, order quantity, or delivery terms. Ask what is included and what must be sourced separately.

Supplier questions to include in your inquiry

• Can you provide a current technical data sheet and a cross-section for the exact PE-RT (EVOH) pipe offered?
• What pressure-temperature limits, connection methods, and installation conditions apply?
• Which product standards or destination-market requirements are supported by available documentation?
• How are production batches identified, and what quality records can be supplied with an order?
• What are the minimum order quantity, available dimensions, coil lengths, packaging, production lead time, and shipping terms?
• Can you confirm compatibility with the project’s fittings, manifold, and installation tools?

At HTIAN, we encourage buyers to send a project specification or inquiry sheet rather than requesting a price for an undefined pipe. This helps us clarify dimensions, construction, quantities, destination, and document requirements before quotation. Product availability, customization options, and delivery timing should be confirmed for each order instead of assumed from a general catalog description.

Common Selection Mistakes to Avoid

One frequent mistake is choosing pipe based on diameter and price while leaving operating temperature and pressure unspecified. Another is assuming that the EVOH layer makes a system immune to corrosion or that all PE-RT EVOH products have identical barrier performance. Buyers should also avoid treating an example layout, operating value, or supplier statement as a final engineering specification.

Do not overlook installation and sourcing details. A pipe can be technically suitable yet create project delays if its fittings are incompatible, its documentation is insufficient for the destination market, or the coil format does not suit the installation plan. Confirm these points before approving a purchase order, and make sure the order description matches the approved technical submission.

Conclusion: A Practical Next Step

The right factory PE-RT (EVOH) pipe for an agricultural greenhouse is the product whose documented construction, dimensions, and pressure-temperature limits match the heating design and installation environment. Define the project conditions first, verify the barrier and product documentation, check fittings and layout compatibility, and compare suppliers on traceability, order terms, and technical support as well as price. For a quotation from HTIAN, prepare your target dimensions, operating conditions, estimated quantity, destination market, and any required standards or documents so we can review the request against the project needs.