Just saying but heaters need to be plugged directly into the wall or mains.
And I’ll add the reason for this (which also counts for portable air-con or anything that draws a lot of power) is that it’s a fire hazard otherwise. The cords on the appliances are specially rated to draw that much power, where most power boards/extension cords are not, so they can heat up and catch fire. It’s also the reason why cords on such appliances are also very short, as there’s less risk of them overheating and being a fire risk.
I found this out once with a tiny space heater plugged into a very old powerboard. It was all working fine, but then one day I wen to move the power board and unplugged the heater – and found that under the plug where I couldn’t see it, the powerboard had completely melted away. Like there was a 1 inch hole in the plastic. I have no idea how it was still working or how it didn’t catch fire.