If wiping the nozzle returns the burner to normal performance then the restriction would appear to be on the outside and not the inside of the nozzle so it would seem that it might not be contamination in the gas, the tank or the pipework that is causing it.

Does the nozzle appear to be discoloured in any way, i.e. does it look like soot deposits? Can you see anything on the exterior surface that you appear to be wiping away? Have you tried using a spotlessly clean cloth to wipe it and then trying to see what you have on the cloth afterwards? Just some ideas to try to narrow it down.

As for nozzle prickers, there is a potential for damage to the inside face of the nozzle bore if not used with great care, so I prefer to simply blow some compressed air back through the nozzle to clear it. A soak in warm soapy water beforehand might be beneficial as well.

When you say it burns OK do you notice any change in performance during use or do you see a consistent performance? Is the plant stored in a cold environment overnight?

Sorry for all the questions but there are a lot of unknown parameters at the moment so we need to try to eliminate a few possibilities.

Edited By Richard Simpson on 18/07/2019 22:58:27