I'm at my wits end. I just moved into a new (for me) 2 story house (1998) that has some weird heating issues. The house is about 3200 sqft the upstairs is heated by a furnace located in the attic. its an Amana AMH80453ax 2 stage variable speed gas furnace. there are 4 bedrooms upstairs all supplied by this furnace.
Here is the issue: Our master bedroom is regularly 10 degrees colder than the set thermostat temperature and the rest of the upstairs. BUT not all the time. This is with all the doors open between rooms. A few other important notes -- Our bonus room is on the 2nd floor and is heated by the downstairs unit. This room is regularly 5 degrees warmer than the stated thermostat. The downstairs furnace is a self contained A/C/Furnace outside and the duct work is in the crawl space. I live in Tennessee. Also, based on my amateur analysis the air coming out of the vents upstairs is not very warm and normally "feel" of low volume. I have checked the duct work several times and it seems to be fine without any leaks/ no dampers blocking the flow. Clean filter. The master bedroom is not over the garage or has attic stairs. The windows are the same in this room as the rest of the house.
Does anyone have any thoughts on this?