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?
In: 2851
I get the idea and tradition of countering a down draft and avoiding poor convection flows, but how much of this is really tradition and hypothesis (which predated our ability to accurately model this) Vs practical reality?
(I) a lot I’m pretty sure came down to building design convenience and tradition,.under the window is a handy place to fill with radiator that is often hard to use for anything else, on another wall a radiator will take wall space, esp traditional horizontal ones.
(Ii) laying pipes to outer walls tends to extend pipe run (sometimes hugely), under many national codes these don’t need to be lagged, this will lead to loss, and a greater pressure drop & demand on the system
(Iii) heating air next to any window also increases the temp gradient, and that (disregarding flow) increases heat loss, almost linearly with temp gradient. The point of the Q I think, and v good Q IMHO.
(Iv) it puzzles me how many radiators are positioned to flow hot air behind a curtain or blind, rather than using the curtain as a thermal barrier, newer blinds might also be pretty helpful in disrupting down/convection currents
It’s a looong time since I studied thermo, but back then there was no way near enough computing power to model a fridge, let alone something as complex as a room! Got a feeling we could do with revisiting yesteryears’ hypotheses here’s with some tests and modern modelling.
Look for a channel called “skill builder” on you tube.
He explains it quite well with little sketches too hahah
Imagine you’re a medieval soldier in a walled city. An invading army is incoming.
Would you post up on the city wall to fight the invaders right where they’re trying to come in? Or would you immediately retreat to the keep and let that invading force flow over the wall and into the city unimpeded?
Many of my central heating ducts are also located adjacent to window but in the ceiling. I’ve often wondered why they would be located there.
Convection. Warm air rises and causes cooler air to be pulled in under it from the other side of the room. The cool air being pulled in lowers the pressure above it which causes the warmer air that has risen to the ceiling to move into the room away from the window.
If you looked sideways at a room with the radiator and window on the left wall the air would be making a circular pattern in a clockwise motion. The warm air is being pulled *away* from the window at the top of the room and the cooler air at the ground is pulled towards the radiator which then heats it up.
And on the top of all that said before, why ruin another wall with radiator when you have already ruined one with the window. Think furniture.
In addition to all the heat related reasons I always thought that since you already can’t put a furniture thing on this section of the wall, might as well use the leftover for another thing that can’t move and would block another section
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.
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.
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.
Latest Answers