Hi paddie,
Pls take note that daikin R22 inverter is a old model (rated 3 NEA ticks).. and true.. they are the only one with R22 inverter now..
Using back old pipes, have to take note of ur current capacity of ur FCU.. Pipe size might be a issue..
Pm me if u need any more details as these details are given from my friend..
Hope this helps..