QUOTE(slimey @ Jun 3 2018, 06:07 PM)
1. cost more.
more work for the installer
2. the more stuff done.......the more prone to error and mistakes.......so why disturb a properly functioning aircon?
3. different refrigerant in previous pipes.
incorrect installation could leave lubricant that is incompatible with the new one. causing lumps to form and burnout the compressor.
4. aircon of 20 years..........likely using old pipes that is too thin........likely 0.5 or 0.4 mm thickness..........cannot be used for r32 or r410a which are high pressure operation gas.
will need to install new pipes and insulator.
Honestly, cost wise, I don't mind paying a little extra as long as they do a neat and decent job without any return jobs. I just leave it at his hands as we have been using him for our residences and offices so far no issues with his work and return jobs needed for work carried out by him. So happen to become a friend after using him all this while.
Pipings wise, my installer verified is compatible. Have been using pipes of Inaba Denko brand back then when we bought those units. Just need nitrogen flushing. He knows what he doing, main thing honest. If it cannot be done, he will just tell me it cannot be done, if there are risks, he will explain the pro and cons and ask me to decide end of the day.
No offense, not instigating anything here