Hello all! I just purchased a new home in Knoxville, TN and had some questions about the existing HVAC setup here. I've researched as far as I can online and I'm stuck on a few things. I have two units outside. One unit is very big and runs the downstairs Model # - RRNA-B024JK06E. One unit is very small and runs the upstairs Model # - RAND-030JAZ.

I had issues finding the furnace(s) so I turned the heat on downstairs first, went outside and heard the gas burning in the compressor unit. So I'm assuming there isn't a furnace for the downstairs and it's an all in 1. I found the furnace upstairs... It's up in the attic with no steps so I need to go purchase a bigger latter so I can get the model # for the furnace.

Here are all of my questions. Please let me know if I need to provide anymore information to find out the answers... Thanks again for any help with this...

1.) I know I need to change the filters on the return upstairs and downstairs but is there maintenance that needs to occur with the furnace upstairs or the units outside? Filters, ETC.?

2.) How do I find out if I have any form of alternate heat? Electric backup? Looking at my bill, looks like gas is used 100% of the time upstairs and downstairs. Maybe I do not have backup heat??