Just had a new heat exhanger and was recommended a Magnaclean as there is sludge in the system. Is the Professional or Twintech model or even another make best? The Twintech looks like a good idea as it's supposed to remove magnetic and non-magnetic particles. Is it essential to flush the system before fitting one? I was thinking of fitting a Magnaclean and then cleaning it regularly, then doing a thorough flush next spring.