SteveUKmidlands

I had a complete burn out on my Saphire spa and had the Davey/Spa-Quip Spa Power PCB - SP600/SP601 board replaced by a hot tub repair company. Ever since when running after a few seconds it stops quoting error 6. The repair company now wont respond to email or telephone so i'm stuck. This error should mean no water moving across the heater and hence shuts down the system. There clearly is water moving across the heater as all of the pumps bubble, blower, etc work. There are 3 sensors on the heater tube. A Klixon (thermostat type device), optical sensor and temperature sensor. When i disconnect the optical sensor i get error 8. When I disconnect the temperature sensor I get error 4 so i feel these must be OK. I have changed the Klixon...same result error 6! Now if i open circuit the Klixon the error goes away...but heater doesn't work! There has to be something simple and obvious but I can't find it help please! Steve