Product Overview
Reliable custom rubber parts for industrial applications
Quick Answer
This EPDM heat exchanger siphon drain hose is a preshaped rubber tube designed for condensate evacuation between heat exchanger and siphon assemblies.
EPDM Heat Exchanger Siphon Drain Hose — Acid-Resistant Preshaped Condensate Evacuation Tube for Condensing Boilers & HVAC
Product Overview
The EPDM Heat Exchanger Siphon Drain Hose is a precision preshaped elastomeric condensate evacuation tube engineered to drain acidic flue gas condensate from the heat exchanger of condensing boilers and high-efficiency HVAC units directly into the siphon trap assembly. Manufactured from EPDM 60 Shore A, it withstands continuous operating temperatures of 80°C (peak 90°C), resists sulfuric, nitric, and hydrochloric acid condensate at pH 3–5, and is designed to meet the requirements of EN 15502-2-1 paragraph 8.103 — the European standard governing condensate handling in gas-fired heating appliances. The part features a complex multi-bend preshaped geometry with a stepped outer cuff (Ø31/Ø25/Ø23.2 mm) for precision engagement into the siphon body, and a narrow inlet tube (Ø18.8 mm) for connection to the heat exchanger drain port.
What Is a Heat Exchanger Siphon Drain Hose?
In a condensing boiler or high-efficiency HVAC unit, hot flue gases pass through a secondary heat exchanger where they are cooled below the dew point — causing water vapor to condense out as liquid. This condensate is highly acidic (pH 3–5), containing dissolved sulfuric, nitric, and hydrochloric acids formed from combustion by-products. The heat exchanger siphon drain hose routes this acidic liquid from the heat exchanger drain port, through an integral siphon trap loop, and into the appliance siphon body — simultaneously evacuating condensate and maintaining a liquid seal that prevents combustion flue gases from migrating back through the drain circuit. The siphon loop geometry is a mandatory functional requirement under EN 15502-2-1 §8.103 for positive-pressure condensing appliances.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Material | EPDM (Ethylene Propylene Diene Monomer) |
| Hardness | 60 Shore A |
| General Tolerance | ±0.2 mm |
| Continuous Operating Temperature | 80°C |
| Peak Operating Temperature | 90°C (intermittent) |
| Chemical Resistance | Sulfuric acid (H₂SO₄), nitric acid (HNO₃), hydrochloric acid (HCl) |
| pH Range | 3 ≤ pH ≤ 5 |
| Compliance Standard | EN 15502-2-1 §8.103 |
| Inlet Tube OD | Ø18.8 mm (heat exchanger connection) |
| Siphon Cuff Inner Bore | Ø23.2 mm |
| Siphon Cuff Mid Step | Ø25 mm |
| Siphon Cuff Outer Flange | Ø31 mm |
| Siphon Cuff Insert Depth | 26 mm |
| Overall Height | 79.5 mm |
| Overall Horizontal Offset | 78.3 mm |
| Upper Bend Angle | 95° |
| Upper Bend Radii | R12 mm (outer) / R13 mm (inner) |
| Siphon Loop Radius | R100 mm |
| Siphon Loop Angle | 105° |
| Siphon Loop Width | 35 mm |
| Outlet Bore | Ø22 mm |
| Reinforcement | Unreinforced (low-pressure drain application) |
| Color | Black (standard) |
| MOQ | 1000 pcs standard |
Geometry & Design Features
The hose combines three distinct functional zones in a single preshaped component:
Upper Inlet Tube (Ø18.8 mm)
A narrow-bore cylindrical tube connecting to the heat exchanger condensate drain port. The small bore ensures efficient condensate drainage even at minimal hydraulic head, preventing liquid backup into the heat exchanger.
Primary 95° Elbow (R12/R13 mm)
A tight-radius 95° bend transitioning the vertical inlet run to the horizontal routing path — engineered to the compact internal chassis geometry of wall-mounted condensing appliances. The close radii (R12 outer, R13 inner) are achievable in EPDM 60 Shore A without kinking due to the material’s high elasticity and the precision mandrel or mold geometry used during vulcanization.
Siphon Loop (105°, R100 mm)
A wide-radius 105° P-trap loop forming the integral condensate seal. The large radius (R100 mm) minimises flow restriction, ensuring consistent self-draining under gravity. The 35 mm loop width accommodates the liquid column required to maintain the gas seal under the positive-pressure conditions of a condensing boiler flue system.
Stepped Siphon Engagement Cuff (Ø23.2 / Ø25 / Ø31 mm)
A triple-stepped outer profile providing radial sealing at the Ø23.2 mm bore, intermediate interference fit at Ø25 mm, and positive mechanical retention at the Ø31 mm outer flange — ensuring a secure, leak-free press-fit engagement into the mating siphon body without additional clamps or fasteners.
Material Selection Guide
| Material | Key Properties | Typical Use Logic | Points to Confirm |
|---|---|---|---|
| EPDM 60 Shore A | Good water, condensate, ozone, and aging resistance | Suitable for heat exchanger siphon drain hose applications | Oil, fuel, and grease exposure should be avoided or reviewed separately |
| Acidic Condensate Resistant EPDM | Suitable for acidic condensate conditions within the specified pH range | Used for heating appliance condensate drainage systems | pH range, acid type, and temperature cycle should be confirmed |
| Custom EPDM Compound | Adjusted hardness, temperature resistance, or sealing behavior | Used when the application requires modified sealing force or durability | Any change should be confirmed against the working conditions and standard requirement |
Why EPDM 60 Shore A Is Specified
EPDM is the industry-standard material for condensate drain hoses in condensing heating appliances — displacing Neoprene and Nitrile due to its superior performance across all relevant failure modes:
- Acid condensate resistance — EPDM withstands prolonged contact with sulfuric, nitric, and hydrochloric acid condensate at pH 3–5 without softening, swelling, or losing structural integrity; NBR and CR degrade rapidly under the same conditions
- Ozone resistance — the sealed boiler cabinet environment contains ozone generated by electrical ignition and controls; EPDM’s saturated polymer backbone is inherently ozone-resistant, while NBR and SBR crack under ozone attack
- Thermal cycling resistance — the hose is repeatedly heated to 80–90°C and cooled to ambient over the appliance service life; EPDM maintains flexibility and compression set without hardening or cracking across this temperature range
- 60 Shore A hardness — the specified hardness balances siphon cuff interference fit retention (requires adequate stiffness for sealing) with the flexibility needed for the 95° tight-radius upper elbow and the press-fit assembly installation force
- EN 15502-2-1 §8.103 compliance — EPDM is the approved material class for condensate system components under this European standard for gas-fired heating boilers
EPDM vs. Alternative Materials for This Application
Compliance — EN 15502-2-1 §8.103
EN 15502-2-1 is the European harmonised product standard for gas-fired central heating boilers — covering Type B (open-flue) and Type C (room-sealed) appliances across all capacity ranges. Paragraph 8.103 specifically governs condensate drainage system requirements, including:
- Material durability — all materials in contact with condensate must withstand the acid concentrations produced by flue gas cooling over the appliance service life
- Siphon trap function — the condensate drain must incorporate a liquid trap preventing backflow of combustion products through the drain path
- Drainage performance — the system must drain condensate reliably under normal operation and defined fault conditions
- Freeze protection — drain routing and materials must not result in condensate freezing under defined cold-weather conditions
The integral 105° siphon loop geometry and EPDM 60 Shore A compound of this hose directly satisfy the §8.103 material and functional trap requirements.
Condensing Boiler & HVAC Applications
This hose type is specified across the full range of condensing heating and cooling equipment:
- Wall-mounted condensing gas boilers — primary application; drain heat exchanger condensate into appliance siphon body in compact cabinet geometry
- Floor-standing condensing boilers — larger-bore variants of the same drain topology
- Condensing combination boilers (combi-boilers) — dual-function heating and DHW appliances with the same condensate management requirement
- High-efficiency gas furnaces — horizontal or vertical flue condensate drain hoses for North American forced-air heating systems
- Condensing water heaters — drain condensate from secondary heat exchanger in high-efficiency hot water systems
- Commercial HVAC condensing units — drain acidic condensate from large commercial condensing heat exchangers
- Heat recovery ventilation (HRV/ERV) units — drain condensate from heat exchanger cores in balanced mechanical ventilation systems
Customization Capabilities
Julong Rubber engineers this hose type to exact OEM appliance requirements:
- Geometry — any combination of bend angles, radii, loop geometry, and straight run lengths; matched to OEM CAD drawing or reverse-engineered from physical sample
- Bore sizes — inlet and outlet diameters from 8 mm to 50 mm; equal-bore or reducer transitions within one hose
- Siphon cuff profile — single, double, or triple-step engagement profiles; OD and depth matched to mating siphon body
- Hardness — 50–70 Shore A range; 60 Shore A standard for condensate siphon hose applications
- Convoluted zones — molded corrugated flex sections can be integrated at any position for chassis compliance
- End connections — plain cut, bead-rolled, barbed push-fit, flanged, or quick-connect boss integrated
- Color — black standard; grey or white available for appliance interior aesthetics
- Compliance documentation — EN 15502-2-1 material and function data, RoHS/REACH declarations, material data sheets on request
Why Source from Julong Rubber?
✅ RFQ response within 24 hours
✅ EN 15502-2-1 §8.103 capable — acid condensate resistance and siphon trap geometry requirements met
✅ EPDM 60 Shore A — exact compound hardness as specified for condensate siphon hose applications
✅ ISO 9001:2015 certified manufacturing and inspection
✅ In-house EPDM compounding — acid-resistant grades optimized for pH 3–5 condensate service
✅ Precision tooling — mandrel and matched-metal mold to ±0.2 mm general tolerance; 7–15 day tooling lead time
✅ Reverse engineering capability — from physical sample, 2D drawing, or 3D CAD file
✅ Low MOQ — 100 pcs production; 5–20 pcs first-article/prototype
✅ Multi-language technical capability — drawings in English, French, German, and Chinese interpreted
✅ 25+ years HVAC and appliance rubber component supply to European and global OEM markets
How to Order / Request a Quote
To prepare an accurate quotation, please provide the 2D drawing, 3D file, physical sample, or drawing reference for the EPDM heat exchanger siphon drain hose. Important details include connector diameters, hose routing, bend radius, material hardness, tolerance, temperature requirement, and condensate resistance requirement.
FAQ
▼ Can you produce this EPDM heat exchanger siphon drain hose based on the drawing?
Yes. The hose can be produced according to the drawing-defined material, hardness, connector dimensions, molded routing, tolerance, temperature resistance, and acidic condensate resistance requirements.
▼ What material is specified for this hose?
The drawing specifies EPDM rubber with 60 Shore A hardness. This material is suitable for water and acidic condensate drainage applications when matched to the required working conditions.
▼ What temperature condition is required?
The drawing note requires temperature resistance of 80°C in continuous service and 90°C in peak conditions.
▼ What condensate resistance is required?
The hose must resist water and acidic condensates related to sulfuric, nitric, and hydrochloric acid components, with a specified pH range of 3 ≤ pH < 5.
▼ Can the dimensions be modified for another assembly?
Yes. Connector diameters, bend radius, overall routing, and sealing profiles can be customized if a new drawing, sample, or installation requirement is provided.
Request a Custom Quote
If you need an EPDM heat exchanger siphon drain hose for acidic condensate drainage, molded routing, or heating appliance connection, you can send the drawing, sample, or application details for review. The material, mold design, inspection method, and production process can then be matched to the actual assembly requirements.
