[Serious] Building a mining rig for home heating

It's getting colder and soon I will need to use heating. So, I was considering the long existing idea of using a BTC miner for home heating.

So the question is - what would be the easiest way to do that? E.g. are there any quiet miners that I can assemble into some kind of an array and use as-is for mining.

I know that some companies already sell mining rigs specifically for heating, but they are usually really expensive compared to their output, so I'm considering buying some used old equipment which is not competitive anymore, but when used for heating could seriously offset the heating costs (e.g. -70% compared to regular heater).

I'm pretty much complete noob when it comes to this stuff, so I don't want to try and undertake some impossible challenge :)

Also, if someone has done the calculations - is it even worth it? Considering that I can also use my air conditioner which is a heat pump and thus can generate more heat than it uses in electricity (i.e. 200-300% thermal efficiency compared to a simple resistive heater).