I'm looking for suggestions on what to ask an HVAC person to look for when inspecting the equipment on a home we're probably going to buy. I have a pretty good idea on what to ask, but would appreciate your experience as well. The home is fairly large, with 4 Heil A/C units, and 4 upflow gas furnaces of unknown size. I don't have the model numbers of the Heil units, but see they use Copeland scrolls. The house is 4 years old, so the equipment is modern. I'll be getting an overall home inspection as well, but am planning to ask a local HVAC company we used in the past to come out to look over the equipment and to make sure all is right. Specifically, what should I tell them I want done and what should I ask for? The equipment is in two mechanical rooms, each on either side of the house, so there's no attic work involved unless you think there's a reason they should check ductwork in the attic.
One of the split units does the heating and cooling of a great room, with a 18' flat ceiling. The dual filter return is on the blasted ceiling, 18' up in the air. Rather than buy a tall step ladder for changing the filters, would it be prohibitively expensive to jack the upflow furnace up a few inches and slip a filter box under it? Have you ever done this? What other choices are there for this rather impractical filter location?
The visit would take place during the "due diligence" phase of a purchase, but before we would close the transaction. The power is on, so I would expect the tech to cycle the furnaces and AC's to be sure they start and run. During that time, I suspect he'd check the refrigerant pressures. Would it make sense at that time to add refrigerant if needed, or would you have him come back?
Any other thoughts, suggestions or help would be appreciated.