Because the hot air in the roofspace is already trying to get out and it works better to help it do what its trying to do than to try to stop it doing what it is already trying to do.
Yes, but its better to help it move faster in the direction it already wants to go.
Nope, you move more hot air when you help it to go in the direction it already wants to go, with a fan.
Nope, its just another example of a wind powered fan which helps the air in the chimney move the way it wants to go.
Yes, but is going against the natural flow of the hot air coming out of the roofspace, so doesn't work as well.
Think of electrically powered exhaust fans.
The work much getter moving the air out of the roofspace than moving outside air into the the roofspace.
Makes no difference how that fan is powered, still works better to move the hot air in the roofspace in the way it wants to go by convection.
But with a van, it also works when there is no wind and the van is moving.
Think of an electrically power exhaust fan.
Surely even you can understand that one that is mounted horizontally at the peak of the roof will work better moving the hot air out of the roofspace than moving external air into the roofspace.
That's what those things are, but wind powered instead of electrically powered.
Doesn't work when the boat is unattended and those things are completely automatic, you don't need to know when it might rain and when to shut the window.
Hang on though, to make it spin it has to have drag. If it has drag its using fuel. Might be moor efficient then to streamline the van and run the fan from the van electrics which is there already. Brian
If not trolling, just a hardhead that refuses to accept a better idea that works. Have you tried one?
Any ambient wind will spin the turbine and pump air out. On a perfectly calm day, I doubt there is much gain at all.
Ok, I accept your explanation. What surprises me though is just how much hot air rises. Is there a formula to determine for example, in a container of certain dimensions, how much hotter the top will be than the bottom?
I rarely see them here, on any type of boiler/fireplace arrangement.
I tend to do that when designing desktop computers, but mainly because of where the hot chips are and what needs the most cooling. I have intake fans front bottom cooling the disks, then across the graphics card, then over the CPU then out the top back and/or top.
I would have believed it might make it more comfortable if you're sat lower down in a building, but once it's been running for a while, the hot air should still have escaped, no matter where it's going. And surely a van just isn't tall enough to have much of a temperature differential by height?
That's why I said rain guard. I've seen caravans with a roof vent with a hat n top to stop the rain.
But the power taken from the alternator would surely be just as bad as the wind drag? Both are putting extra strain on the engine. I wonder if anyone has ever studied whether you should (for fuel efficiency) open your car window when driving on a hot day or use the cooling fan (ignoring AC for the moment).
No, I was just asking how it works.... It would appear Mr Speed has provided a satisfactory answer.
Another Hucker troll.
No, a question. But despite having a van half your working life, you couldn't answer it. Mind you, you admitted you couldn't even reverse it!
Brian Gaff wrote
Too radical by far...
But a tiny part of the drag of the whole van.
Not when stationary and most of them are stationary much more than they are moving.
That should be done anyway.
Sure, but that wouldn?t work as well when stationary.
Yes, but its complicated.
Yeah, basically because the standard chimney pot works pretty well when the chimney itself is properly designed so it draws well initially when you are first lighting the fire and are maintenance free.
I only bother with the cpu fan, but don't run mine with covers on.
I don't bother cooling mine but I use the lower speed ones that only get warm to the touch when the room is over 30C before I turn the air cooler on.
I'm not into gaming so mine don't even have a fan. The only game I ever play is Freecell Pro and it isnt exactly demanding of the video card.
Surely if I gave you some facts like....
A room 10m by 10m by 10m. No external sources of heat or draughts, like open windows, heaters etc. The air near the floor measures 20C.
How warm is the air near the ceiling?
Except it lets all the cold air in when the fire is out.
Why is hanging on radical?
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