Leister TRIAC ST Heat Gun: A Technical Overview
The Leister TRIAC ST is a rugged, analog-controlled heat gun developed for reliable, high-output welding of thermoplastics on tough job sites. Delivering up to 700 °C of focused heat via a 1600 W element (230 V AU), it features a robust 2-component handle, ø31.5 mm nozzle interface, and fixed 240 l/min airflow. With no digital components, it’s a go-to tool for trades that demand durability over features. Weighing just 0.99 kg, the TRIAC ST is ideal for roofing, waterproofing, civil liners, plastic fabrication, and tarpaulin work — especially where simplicity and robustness are key.
Core Features & Specifications
- 1600 W output at 230 V with rugged, site-ready analog control
- Temperature range from 40 °C to 700 °C — ideal for thick materials and fast welding
- Fixed airflow of 240 l/min delivers reliable, uniform heat output
- Ergonomic two-component handle designed for fatigue-free use
- Nozzle connection: ø31.5 mm (M14) — supports over 80 Leister nozzles and attachments
- Lightweight 0.99 kg construction — ideal for overhead or prolonged use
- 3.0 m power cord with AU 10A, 3-pin plug for local jobsite compatibility
- Certified to CE, UL, KC, and S+ standards
- Outdoor rated with IP class II protection and sealed internals
The Leister TRIAC ST Heat Gun Advantage
- Pure reliability — no digital screens, no menus, just dependable heat
- Built to endure heat, dust, knocks, and years of field use
- Backed by Swiss engineering — durable parts and long heating element life
- Simplifies training — consistent results even for new installers
- Ideal backup or site-ready option for teams using TRIAC AT or automatic welders
Applications in Practice: Trade Scenarios
For Roofers (On-Site Applicator): Reliable Membrane Welding Without Digital Failure
The Professional's Challenge
On high roofs, cold starts and tool drops can disable digital guns. Roofers need reliable membrane welding regardless of weather or conditions.
The Adheseal Solution: Engineered Certainty in Practice
TRIAC ST’s analog dial and fixed airflow provide rapid, consistent heat. Set temperature manually and get welding — no calibration or failure-prone electronics involved.
Best Practice Note
Store upright in a heatproof cradle between welds. Use slit nozzles for 1.5 mm TPO at approx. 550–600 °C for consistent seams.
For Civil Contractors (Business Owner): HDPE Liner Repairs in Remote Locations
The Professional's Challenge
Working on HDPE containment liners with no power regulation or shelter can trip digital units. Failures result in delays and increased liner risk.
The Adheseal Solution: Engineered Certainty in Practice
The TRIAC ST works flawlessly with standard generators, tolerates voltage drift, and keeps delivering heat in wind and dust. Lightweight for single-hand use on patches and seams.
Best Practice Note
Use the ø31.5 mm nozzle interface with Leister wide-slot attachments for HDPE. For best fusion, weld between 580–640 °C with overlapping strokes.
For Fabricators (On-Site Installer): Quick Field Repairs on Flexible Plastics
The Professional's Challenge
Crews in remote signage or tarpaulin installations need a heat gun that heats quickly, travels light, and works off site power without error codes.
The Adheseal Solution: Engineered Certainty in Practice
The TRIAC ST runs straight from 10A leads and fires up fast. With no digital lag or menu, it delivers quick-response heat for patching, shrinking, or forming coated fabrics.
Best Practice Note
Use the fine nozzle tip for detail work. Avoid holding the gun in one spot — continuous movement ensures clean welds without burning.
Frequently Asked Questions
Is the TRIAC ST compatible with Australian 10A power outlets?
Yes, the TRIAC ST ships with a 10A, 3-pin AU plug and operates at 230 V / 1600 W, making it fully compliant with standard Australian jobsite and workshop power outlets.
What materials can be welded using the TRIAC ST?
The TRIAC ST is suitable for welding thermoplastics including PVC, TPO, HDPE, LDPE, PP, and coated fabrics. It is not designed for non-thermoplastic materials like metals or composites.
Does the TRIAC ST have airflow adjustment?
No, the TRIAC ST delivers a fixed airflow of 240 l/min. This ensures consistent heat delivery without the need for separate fan control, making it ideal for straightforward site use.
Can I use the same nozzles as the TRIAC AT?
Yes. The TRIAC ST uses a ø31.5 mm nozzle connection (M14), compatible with over 80 Leister welding and forming nozzles — including all standard attachments used on the TRIAC AT.
Is this heat gun suitable for continuous site use?
Absolutely. The TRIAC ST is designed for heavy-duty, continuous operation on construction sites, workshops, and field installations. It has no digital components, making it highly resistant to jobsite conditions.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Welding PVC/TPO roofing membranes | High heat and durable analog control — perfect for outdoor roofing with no risk of digital failure | Roofers, Waterproofers |
| Repairing HDPE liners in tanks and bunds | Reliable heat delivery in remote or dusty conditions with portable generator compatibility | Civil Contractors, Environmental Engineers |
| Heat shrinking cable wraps or sheathing | Steady airflow and no digital lag — ideal for cable trays and overhead conduit | Electricians, Communications Techs |
| Patching or forming coated tarpaulin | Lightweight and ergonomic for quick handheld use with Leister slit nozzles | Canvas Workers, Awning Repairers |
| Detail welding for commercial vinyl flooring | Fine control over positioning and reach — easy access into corners without fatigue | Flooring Installers |
Applying Leister TRIAC ST Heat Gun: Enhanced Protocols & Best Practices
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Step 1: Prepare the Work Area
Ensure a safe, dry, well-ventilated environment. Lay out substrate material and select the appropriate nozzle for the job.
Membrane Welding
Position membranes with a minimum 40 mm overlap. Clamp or weight ends to prevent wind interference. Clean mating surfaces with a dry cloth.
Plastic Forming
Secure the workpiece using clamps or formers. Pre-clean the surface to remove dust or release agents.
Timing: 2–3 minutes setupPro Tip: Use a grounded RCD-protected circuit and avoid plug adaptors or boards. -
Step 2: Power Up and Preheat
Plug into a 230 V outlet. Turn the analog dial to the desired heat level — refer to material guidelines for temperature estimates.
PVC Roofing Membranes
Set to approx. 550–600 °C for 1.5 mm PVC with a slit nozzle. Allow 45 seconds to reach temp.
HDPE Liner Patching
Use a wide-slot nozzle and set to 600–650 °C. Test on scrap material before welding live seams.
Timing: Heats up in 30–60 secondsPro Tip: Always test your heat setting on offcut material before starting production welds. -
Step 3: Perform Welding or Forming
Maintain a consistent angle and motion. Use Leister rollers to apply pressure during overlap welding or shaping.
Overlap Welding
Insert the nozzle between overlapped membranes. Move steadily along the seam while pressing with a silicone roller to form a strong bond.
Forming Acrylic or Polycarbonate
Heat slowly from a distance with low-to-mid setting. Flex into jigs or forms gradually to avoid stress fractures.
Timing: 5–10 seconds per 300 mm weld (approx.)Pro Tip: Avoid overheating. Bubbling or charring indicates excessive temperature or slow movement. -
Step 4: Power Down and Cool
Turn off the heat dial and unplug the gun. Allow the unit to cool naturally before storing or moving it.
Jobsite Use
Place on a heat-safe surface or cradle. Do not coil the cable while the unit is hot.
Workshop Storage
Clean nozzle with a dry cloth once fully cool. Store in its case or protective sleeve.
Timing: 2–3 minutes natural cool-downPro Tip: Never dunk or rapidly cool the nozzle — thermal shock can crack the heating element.
Limitations & Safety
Product Limitations
The TRIAC ST is not designed for precision control — it lacks a digital temperature readout. For applications requiring exact temperature regulation, use the Leister TRIAC AT.
Not suitable for welding non-thermoplastic materials such as metal, wood, or epoxy composites.
Fixed airflow (240 l/min) may not be suitable for highly delicate plastics that require lower air pressure.
Safety & Handling Requirements
Personal Protective Equipment
Wear heat-resistant gloves during use. Safety glasses are recommended when working with overhead seams or around softening plastic. Avoid wearing loose-fitting clothing near the air intake.
Ventilation Requirements
Use in a well-ventilated area. When heating PVC or other coated materials, always ventilate the space to avoid exposure to potentially harmful off-gases.
Fire & Handling Precautions
Do not leave the tool unattended while hot or plugged in. Always place on a non-flammable, heat-resistant surface. Never rest the nozzle directly on materials or floors.
Emergency First Aid
Eyes:
Flush with cool water immediately for at least 15 minutes. Seek medical attention if irritation persists.
Skin:
For burns, rinse with cool water and apply sterile gauze. Do not use creams or ointments unless directed by a medical professional.
Inhaled:
Move the individual to fresh air. If breathing difficulties occur, seek immediate medical assistance.
Swallowed:
Not applicable — this is an electrical tool. If any component is swallowed, contact emergency services immediately.
Seek medical attention immediately in all cases of serious exposure.
Substrate Compatibility Guide
PVC (Polyvinyl Chloride)
Welding Range
Set between 500–600 °C. Use slit nozzle for seams. Clean surface with dry cloth before welding.
No primer required
Welds direct with excellent fusion. Compatible with standard Leister overlap nozzles.
TPO (Thermoplastic Polyolefin)
Welding Range
Recommended 550–620 °C with slit or wide-slot nozzle. Clean with IPA before welding.
No primer required
Requires steady pressure and overlap technique. Test seam strength after cooling.
HDPE / LDPE (Polyethylene)
Welding Range
Set to 580–650 °C. Use wide-slot nozzle and polyethylene welding rod if required.
No primer required
Material softens quickly. Test small area first. Keep heat gun moving continuously to avoid surface burns.
Coated Fabrics / Tarpaulins
Welding Range
Approx. 520–580 °C. Use flat or slit nozzle with low angle. Clean gently with soft cloth.
No primer required
Ideal for banners, awnings, tents, and truck tarps. Avoid overheating edge coatings.
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