If you increase it 1000 fold it would still be less than 10% of the heat the sun provides.

That's incorrect. It's in the order of 25% of the heat reaching the Earth's surface, or maybe 35-40 watts of heat per square metre.

That's roughly ten times the warming effect of doubling CO2.

Now, I don't have a climate model handy to simulate this in detail but I would suggest "render the Earth uninhabitable" is a close enough approximation to the actual effects to suggest it's a terrible idea and anyone seriously proposing it should be laughed out of the room until they've done their homework.