I'm here out of interest in the technology, its development, and design improvements.
I sometimes repair my own HVAC equipment or upgrade it from time to time. I have a vendor I can trust and won't ask any DIY questions here and will abide by the rules.
Repair and engineering are not for everyone but it's all I have ever done. I don't do HVAC work as a profession but study of the systems is a hobby.
When there's real trouble I call on my HVAC repairman friend and he takes care of the major malfunctions and helps with upgrades or modifications. I don't bother him with minor stuff. He's in charge of the charge, so to speak. I'd rather work with electronics than on the HVAC system. My friends call on me for that.
I believe it's important to develop relationships in the trades and technologies. That way, you trust who is working on your stuff. I prefer to find a good vendor I can trust and stick with them.
Sometimes a few of us get together for BBQ and beer and make working stuff out of pieces, or try to repair some hopelessly ruined thing with only the crudest tools. It's fun.
inverter welder abuse
(^^depiction of experts working with safety precautions. Do not try this at home^^.)
There are Magnehelics on my Janijunk! I like them. There is nothing like a good ugly hack and it got them off the garage floor. (Do not try this at home) Filters need replacing.
I came across this site looking for info on how popular in the industry the 'universal furnace blower motors' are. Maybe you have seen them, a single motor replacing 1/3HP to 1HP sizes. Personally I don't like the paticular one here because of its ampere draw over the 1/3HP original but I have not searched the information out yet and I see there's a lot more to learn here than look that sort of obscure stuff up. But it is an interest.