Can you cover a vent with cardboard?

You also can build your own cover out of almost any heat-resistant material. Fitted pieces of cardboard wrapped in aluminum foil and held in place with small weights or magnets is one very low-cost solution.

Rest of the detail can be read here. Correspondingly, can covering a vent cause a fire?

Fire, Freeze and Financial Hazard When a vent is blocked, less cool air flows across the heat exchanger, which then overheats, and expands, and cracks. It's unlikely but not impossible that blocking a heating vent and causing the furnace apparatus to overheat could cause a fire.

Secondly, can you cover a vent? You could mess with the air flow. Just because you cover the vent, it doesn't mean your HVAC system knows that. It will keep pushing air to those vents, and if they're closed, you could cause a buildup of air pressure and insufficient airflow which could damage your system.

In this way, is it bad to cover a vent with a bed?

Its fine to put a bed over a heat vent as long as you dont have the box spring sitting right on top of it unless you close the vent. If you have it on a some kind of frame with a couple inches of clearance, you will be fine. I would avoid putting a "bed skirt" on though, other wise you will lose circulation.

Can you put furniture in front of vents?

Here are some simple ways you can do just that: Keep couches, chairs and other large pieces of furniture at least 10 inches away from your cold air return vents. Avoid covering your cold air return vents with curtains, drapes or rugs. Clogged air filters can also cause cold air return blockages.