eli5: Why are radiators in houses often situated under a window- surely this is the worst place and the easiest way to lose all the heat?
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I read that radiators were originally designed to be used with an open window during the 1918 influenza pandemic
Think about what insulating is doing, keeping the warm air from going outside because that’s how you lose heat, it goes outside. It can only possibly go outside by going through an exterior wall. Therefore, heat is only required on exterior walls where the heat is escaping, only to replace the heat lost. Placing it by the worst spots, windows, gets you the most even heat distribution, the heat is only counteracting the loss, and the rest of the building stays a constant temperature because the interior isn’t losing heat to the cold exterior.
Also, this is NOT true for AC, AC counteracts the hot air outside, the hot air from all the electronics, lights, stoves, etc, and it counteracts body heat. Therefore AC needs to be distributed throughout the building, and really big buildings need so much AC that many don’t need heat even when it’s very very cold outside because their internal heat from running stuff is more than they lose through exterior walls.
This is wonderful new information I did not have. I also wondered why and this makes perfect sense!
I guess the best way to explain it like you’re 5 is this: the reason you think it’s the worst spot is actually the exact reason why it’s the best spot.
Hot air from a radiator doesn’t actually mix that well with the rest of the cooler air in a room.
When I give my kids a bath, I fill the tub with very hot water first (cast iron tub soaks up a lot of the heat, so we have to warm up the tub itself as well as the water). After some point we add cold water.
But adding cold water doesn’t actually make the bath water an even, cooler temp. So I have to stir the water continuously so there are no pockets of hot water.
Same for air. If there is no air movement in a room, the hot side will stay hot and the cold side will stay cold. But cold air forms a draft of cool air current because cold air wants to drop to the floor. (Cold air is denser than warm air). The movement of cold air falling to the ground creates an air current that can stir the room air.
So air moving over the radiator helps to move all of the air around the room, instead of having hot spots and cold spots.
I’ve tested this myself with electric oil radiators that we used to put on the far wall away from the window; and later learned to move it under a window or in front of a cracked interior door.
Nobody’s talking about the uniformity of the room temp. If you put a radiator at the opposite side of the room you will have a hot spot and a cold spot in the room neither of which is confortable.
Same reason that supermarkets have air conditioners above the doors blowing cold air during the summer. It’s to block the undesirable temperature from getting in.
The heat is going to be lost no matter what. Placing the radiator near the window helps to counteract the cold draft from the window and thus causes the whole room to have a more level temperature. Placing the radiator far away from the window will make for a warm side near it and a cold side away from it. If the radiator is set to a normal temperature limit, like 68F/20C then the side of the room near the window could be a few degrees lower.
On the contrary, it is the best place because that’s where cold air might leak into the house… so as it leaks in, it gets heated up. If you place it in the core of the house, then the window areas will be cold, and the core of the house would be hot. With radiators under the windows, no cold air can reach the center of the house without a bit of warming over the radiators.
I thought it was partly to do with a simple ergonomics issue of that wall space is already partly unusable in terms of putting furniture there so may as well put something else there that should also not be blocked by furniture.
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