please explain staged heating on heat pumps
Just bought a trane 3T units w/vs air handler and 15KW plates.
What is staged heating? One guy says it involves an outside stat that governs when the 1st stage (5KW) kicks in....say at above 35 degrees. Perhaps below 35 degrees the entire 15KW kicks in. Upside, you do not ALWAYS run at 15KW when aux heat is required. Down side, he says sometimes you want to quickly warm your home and if its a little warmer out that day, only the 5KW kicks in and it will take longer to warm the house.
Other guy says it happens automatically but did not mention an outside stat or how it works.
How does this work? Is it worth having or can it be a nuisance? Does it cost more to install? In reality how much does it save over a straight 15kw, whichI would think would kick in for a shorter period of time and warm up faster?