When you notice bubbles coming from the ports like the video attached (heat port) this is due to trapped air in the PCU system (airlock.MOV). 

You may need to do the following to reduce this from happening;

  • Make sure you turn off the unit, then bleed for around 10-20 seconds until all the air escapes and you're left with just water escaping (Bleed filter housing.gif).
  • Check that all connection o rings are intact and not damaged, noticing the bleed valve o ring (under star-shaped cog) is also in good working order.
  • When fitting your pipes check for damage, use soapy water, and wipe this on the ports or on the inside of your pipes, this will mean a good connection and thread tightening will be made easier.
  • Always be cautious about the amount of chemicals you add, as it can break down plastic and elements that keep the PCU and your spa in good working order. 

Article published by Ali Green

See attached.