I'm new to all this HVAC stuff so forgive me if I get my terminology wrong. We are currently shopping for a new A/C and furnace and were told by two contractors that the pipe coming from the outdoor A/C unit is 7/8" while our interior pipes are only 3/4". They recommended changing the tubing inside our house so that they are all 7/8".

One other contractor said that this wasn't necessary since it was a short run (probably about 25 feet or so) - he said if it was his house he wouldn't bother with changing it out and damaging the ceiling, etc.

Any thoughts on whether or not this change is necessary? Our goal is to have a good system that we don't need to think about for a long time and so I obviously want to make sure it's installed correctly (nor do I want to void any warranties by it NOT being installed correctly).

Any info to help me out would be much appreciated! Thanks...