But... of course there has to be some "genius" explanation that only the most brilliant people can understand and everyone else is just too dumb to see it.Actually, that's the way most things in the Universe are...Take gravity for example.

Unless you want to use a pump system, drains have to have natural gravity fall, and you might not be able to get that in some locations.

I have a gravity system on the main house and a pump system in the ADU.

Sewer can especially be a unique challenge because you either need gravity back toward the house or you need an injection pump to grind up the sewage and shoot it down a higher pressure line.Also, where are you going to park if you convert the garage?

Here's a good article: https://m.startribune.com/gravity-furnaces/135646573/

Remove the 'support' of the ground, gravity is going to take over unless you mitigate it.

What is hurting us is that the home still has the original 100+ year old gravity furnace.

I'll be investing in 3-D and Anti-Gravity companies!

I went the HVLP gravity spray gun route.

Unit B has newer forced air furnace, Unit A has an old gravity style furnace, still functional.