(12-27-2021, 09:22 PM)tomh009 Wrote: They were indeed telling the truth. And it takes a few days because they need to let the system cool down (or warm up) to avoid problems.
A four-pipe system avoids this issue but is presumably substantially more expensive to implement. Both our condo building and the office building (where my office is located) use the two-pipe system.
A bit off topic, but with newer technology it's possible to have a 2-pipe system switch to heating over night and cooling during the day. Here's an article on a school retrofit: Two-Pipe HVAC Makes a Comeback: An Idea Discarded Decades Ago May Be the Future of School Heating and Cooling.
"Changeover can be accomplished with very little loss of energy in 20 minutes with no human intervention whatever."