i'm not just having problems deciding what sort of aircon system to install but i got a bigger headache deciding whether to re-do all the gas / water piping. my new place is actually not new, 2nd-hand, 9 years old, so my parents feel that i should re-do everything in case there're problems in future and i can't hack out the pipes as easily as when i'm doing reno. say is easy, but cost-wise it's a different story! my ID said the aircon ppl will test and check that the pipes are working, but how much can i trust them? any opinions on whether i should re-do or leave it?