Equipment Care & Repair

Heat Weld Gun Care: Elements, Filters and Nozzles

Cooling down, cleaning air filters, changing heating elements and cleaning nozzles on Leister-type heat weld guns, and what to leave to a service center.

Updated · 2 min read

A heat weld gun has three things that wear: the heating element, the air filter and the nozzle. Keep air moving through it, let it cool before shutting it off, and keep the nozzle clean. Do that and it will weld consistently for years. Most guns in flooring are Leister Triacs; the Crain No. 969 is a Triac ST.[6]

Safety

Unplug the gun before opening it.[1] Let it cool before changing nozzles. Welding at too high a temperature can release hazardous vapors; don't breathe them, especially when welding PVC.[4]

Cool down before you switch off

Shutting a gun off hot, with no air moving, is hard on the element.

  • Turn the temperature dial to minimum, let the gun run about five minutes, then switch off and unplug.[2]
  • On the Triac AT, a long press on the e-Drive starts cool-down, and the gun shuts itself off once it's near room temperature.[1]
  • Before changing a nozzle or storing the gun, set it on its stand and let it cool completely.[4]

Air filters

A clogged filter starves the element of air.

  • The air filters on each side come off easily for cleaning, which keeps airflow and output at their best.[3]
  • The Triac AT's overheat warning points to airflow first: clean the air filter and check the nozzle.[1]
  • Check the filters often on dusty jobs, especially after grinding or patching.

Heating elements

Elements wear out, so plan for them.

  • Heating elements aren't covered by the warranty.[2]
  • The Triac AT detects a failed element and tells you to replace it.[1]
  • Changing the element and mica tube is one of the few repairs a user can do.[1] Replacement elements for the Triac ST/AT are 142.718 (120 V) and 142.717 (230 V).[3]
  • Use the gun only on the voltage it's rated for.[4]

Nozzles

Carbon and melted rod build up inside and outside the nozzle.

  • A round brass brush cleans speed welding nozzles, welding shoes, pipe nozzles and wide slot nozzles.[7]
  • Clean the nozzle with a wire brush inside and a stiffer wire brush outside to clear carbon and keep air moving.[8] Crain's kit includes stainless-steel brushes.[9]
  • Restricted airflow is a common cause of uneven heat.[5]
  • Check that the rod tube on a speed nozzle is straight. See Heat weld nozzles and rod.

Leave to a service center

Other than cleaning the air filter and changing the element, repairs go to a Leister service center.[1][2] That includes carbon brushes when the Triac AT warns they're near their limit.[1]

Common mistakes

These shorten element life the most.

  • Switching off hot. Run it cool first.
  • Dirty filters. The gun overheats.
  • Clogged nozzles. Uneven heat and poor welds.
  • Welding too hot. Scorched material and fumes. Set temperature for the rod and flooring.

Guns and parts we carry

These are the guns, kits and nozzles we stock.

References

  1. Leister Triac AT operating instructions
  2. Leister Triac ST operating instructions
  3. Leister Triac ST/AT brochure
  4. Leister hand tools safety instructions
  5. Turbo Heat Welding Tools: FAQ
  6. Crain No. 969 heat weld gun (product page)
  7. Leister: Round brass brush 114.239
  8. Turbo: Supreme Turbo kit
  9. Crain No. 988 vinyl welding kit (product page)

Linked PDF documents are archived copies saved by PreFloor Tools so they stay available if the publisher moves or removes them. Check the publisher's website for the latest revision.

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