
Embezzle a bit more of your building’s heat - blasdel
http://www.marco.org/270919755
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dasht
So, a box fan that looks roughly like the one pictured seems (from a quick
poking around) like it uses 80-150 Watts. Intuitively (not measured, not
scientific - just a hypothesis) it seems like a box fan will also move much
more air than is really optimal for this application. Also, optimal results
are probably obtained by drawing in air close to the ground and forcing it up
through the radiator, not grabbing air from all around and pushing it through.

This seems like an area for experimentation, modeling, and maybe even product
design. Would a few computer cooling fans produce as much benefit at a
fraction of the electricity cost? Even better, maybe, can a very quiet and
just-enough air circulation be built that operates solely on the thermal
energy generated near the hot input side of the radiator? A probably absurd
suggestion but I can think of one past apartment where I would have considered
it: duct work (e.g., dryer vent tubes) combined with computer cooling fans
drawing air from the coldest part of the apt. and pushing it towards the
radiator....

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lutorm
Natural convection will do what you want. (If he removed the bookshelf,) air
will get sucked in from the bottom, heat up, and then rise. The problem is
that the warm air will sit under the ceiling. I think circulation would be
better used to make sure the air doesn't stratify, ie blow some of the warm
air under the ceiling downwards.

It's funny you should write this, because I've been meaning to try exactly
this: I have a 12V cable lighting system running over the steam heat radiator
in the room I'm sitting now, and I was going to put a 200mm computer fan
across the cables blowing down. Power is already up there... ;-)

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lutorm
I don't understand the premise of what he's trying to do. It seems to allude
to a system where someone else decides how hot your place should be, without
any thermostat feedback. In Sweden, there are apartment buildings that have
centralized hydronic heating, but in those cases the hot water is on all the
time and you adjust the temperature in the apartment by changing the hot water
flow using the valve on the rad. If the system turns itself off when it is too
cold in some parts, then he really should demand to have a professional look
at the system instead of hacking it. A heating system that's unbalanced and
not running optimally is likely to waste a lot of energy.

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ilovecheese
> In Sweden...

New York has old, old, old, old infrastructure. It might surprise you to know
that they still dump their trash onto the streets, where it rots in the summer
heat and mixes with AC condensation that drips down (because their AC units
hang out of windows) and creates giant rivers of foul smelling shit water that
you must step over carefully to avoid.

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joshu
IIRC a fair amount of the steam used in NYC is actually generated in NJ and
pumped under the river.

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tokenadult
Passive solar heating worked remarkably well for me when I was living abroad
in a place with so little electricity that I wasn't permitted by the landlord
to have a space heater. I just opened my shades all day during daylight, and
closed them at sunset. That's all, but that was enough to make my room
noticeably warmer than ambient outdoor air temperature--so much so that my
visitors from other units in the same building kept asking me if I was using a
space heater on the sly. Try it; you might like it.

~~~
MikeCapone
Good passive solar design (with the right surface of window to thermal mass)
should be part of the education of all architects, IMO. Would make for more
comfortable buildings and save a lot of fossil fuel energy that we could
better use for something else.

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KC8ZKF
He seems to have a shelf of books on top of the radiator, which will limit its
effectiveness, box fan or not.

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mmt
I would have to disagree. It certainly limits effectiveness without the fan,
but I expect the fan to more than counteract that.

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lutorm
That's what I was going to say: Maybe he wouldn't need the fan if he removed
the shelf.

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seabee
Forced airflow is several times more effective than relying on convection.
Remember that hot air rises, so if the room was narrow, removing the shelf
would indeed be sufficient. However, if the end of the room is quite far, it
will take a quite a little while for heat to circulate.

The fan speeds up the process by sucking a lot more cold air in through the
radiator, forcing it against the warm metal and blowing it out into the room.
(Think why the heatsinks in your computer have fans.)

The shelf may act as a way of ensuring air blows through the entire depth of
the radiator, but I doubt it has any significant effect either way.

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ascuttlefish
This is brilliant. I could have used this in draughty old apartments in
Montreal, with their 12' ceilings and giant old radiators. Yet another of
those "Why the ass didn't I think of... ah forget it" ideas.

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NathanKP
This won't work for long if everyone in the building starts using the same
trick. Better keep that box fan hidden from the neighbors.

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mmt
That assumes that there's a fixed amount of heat being input into the hot
water (steam?) circulation system.

Are there modern boilers that adjust the amount of fuel added and/or the burn
rate, based on the incoming water temperature? Did traditional boilers just
eject the excess as waste heat (perhaps through a steam pressure relief
valve)?

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carbocation
This is surprisingly, and unfortunately, relevant to me. Nice hardhack.

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MikeCapone
Is that The Blank Slate by Steven Pinker?

