I’m going to install the furnace myself since it’s just a gas unit. I notice a lot of companies. I have currently a Lennox and it seemed to work great considering it still heats the home and was put in at 1973. I notice the following companies

Goodman – sells a lot on ebay some people have them dosen’t seem expenive
Trane – are these low quality
bryant
amer stnd – I heard they make good faucets

There are also a couple of other companies such as kenmore and sears that make furnaces. Which ones are good. Which do i have to watch out for.