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Groups > sci.electronics.design > #447363 > unrolled thread
| Started by | rickman <gnuarm@gmail.com> |
|---|---|
| First post | 2017-02-11 22:02 -0500 |
| Last post | 2017-03-01 17:33 -0800 |
| Articles | 12 on this page of 92 — 24 participants |
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Window Heater rickman <gnuarm@gmail.com> - 2017-02-11 22:02 -0500
Re: Window Heater bill.sloman@ieee.org - 2017-02-11 20:57 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 01:02 -0500
Re: Window Heater whit3rd <whit3rd@gmail.com> - 2017-02-11 23:07 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 03:52 -0500
Re: Window Heater whit3rd <whit3rd@gmail.com> - 2017-02-12 18:32 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 21:42 -0500
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-13 10:04 -0600
Re: Window Heater makolber@yahoo.com - 2017-02-13 10:17 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-13 15:30 -0500
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-13 15:39 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-13 20:28 -0500
Re: Window Heater krw@notreal.com - 2017-02-13 20:48 -0500
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-13 13:47 -0800
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 06:56 -0800
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-14 07:17 -0800
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 13:20 -0800
Re: Window Heater George Herold <gherold@teachspin.com> - 2017-02-14 16:17 -0800
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-14 16:28 -0800
Re: Window Heater George Herold <gherold@teachspin.com> - 2017-02-14 17:42 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 21:18 -0500
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 19:20 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 22:42 -0500
Re: Window Heater George Herold <gherold@teachspin.com> - 2017-02-15 06:51 -0800
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-15 06:06 -0800
Re: Window Heater George Herold <gherold@teachspin.com> - 2017-02-15 06:54 -0800
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-15 09:15 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-15 15:02 -0500
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-15 16:38 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-15 19:50 -0500
Re: Window Heater Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-17 11:18 +0000
Re: Window Heater Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-16 08:28 +0000
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 14:07 -0500
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 12:57 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 17:32 -0500
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 19:12 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 14:16 -0500
Re: Window Heater dagmargoodboat@yahoo.com - 2017-02-14 12:53 -0800
Re: Window Heater John S <Sophi.2@invalid.org> - 2017-02-14 16:14 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 17:35 -0500
Re: Window Heater John S <Sophi.2@invalid.org> - 2017-02-15 10:45 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-15 15:06 -0500
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-15 16:46 -0500
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 17:34 -0500
Re: Window Heater bill.sloman@ieee.org - 2017-02-12 04:57 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 18:19 -0500
Re: Window Heater Winfield Hill <hill@rowland.harvard.edu> - 2017-02-12 10:42 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 18:30 -0500
Re: Window Heater Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-12 08:45 +0000
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 03:57 -0500
Re: Window Heater Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-12 09:34 +0000
Re: Window Heater Jon Elson <elson@pico-systems.com> - 2017-02-11 23:52 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 01:07 -0500
Re: Window Heater Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-14 10:40 +0000
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 06:00 -0500
Re: Window Heater John S <Sophi.2@invalid.org> - 2017-02-14 16:17 -0600
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-14 14:28 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-14 17:36 -0500
Re: Window Heater Mikko OH2HVJ <mikko.syrjalahti@nospam.fi> - 2017-02-12 14:54 +0200
Re: Window Heater Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-12 08:56 -0700
Re: Window Heater Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-02-12 20:14 +0200
Re: Window Heater Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-11 00:30 -0500
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 18:56 -0500
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-12 06:35 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 19:01 -0500
Re: Window Heater "dcaster@krl.org" <dcaster@krl.org> - 2017-02-12 17:29 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 21:37 -0500
Re: Window Heater Jon Elson <jmelson@wustl.edu> - 2017-02-13 15:08 -0600
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-13 13:32 -0800
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-12 08:20 -0800
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-12 11:48 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 19:03 -0500
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-13 09:58 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-13 15:33 -0500
Re: Window Heater Jon Elson <jmelson@wustl.edu> - 2017-02-13 15:10 -0600
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-13 13:36 -0800
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-13 15:40 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-13 20:34 -0500
Re: Window Heater krw@notreal.com - 2017-02-13 20:52 -0500
Re: Window Heater Tim Wescott <seemywebsite@myfooter.really> - 2017-02-12 12:02 -0600
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 19:05 -0500
Re: Window Heater Tim Wescott <seemywebsite@myfooter.really> - 2017-02-14 17:49 -0600
Re: Window Heater bitrex <bitrex@de.lete.earthlink.net> - 2017-02-12 13:06 -0500
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-12 19:05 -0500
Re: Window Heater Clifford Heath <no.spam@please.net> - 2017-02-13 11:21 +1100
Re: Window Heater krw@notreal.com - 2017-02-12 19:28 -0500
Re: Window Heater Martin Riddle <martin_ridd@verizon.net> - 2017-02-12 21:57 -0500
Re: Window Heater "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-13 10:01 -0600
Re: Window Heater Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-13 13:49 -0800
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-02-13 20:36 -0500
Re: Window Heater rickman <gnuarm@gmail.com> - 2017-03-01 19:44 -0500
Re: Window Heater George Herold <gherold@teachspin.com> - 2017-03-01 17:33 -0800
Page 5 of 5 — ← Prev page 1 2 3 4 [5]
| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-12 19:05 -0500 |
| Message-ID | <o7qt44$jeh$3@dont-email.me> |
| In reply to | #447432 |
On 2/12/2017 1:02 PM, Tim Wescott wrote: > On Sat, 11 Feb 2017 22:02:32 -0500, rickman wrote: > >> I sit directly under a window much of the time (don't suggest I move, >> there just isn't another practical option). When it is cold the window >> has a draft that is downright brutal. I plugged the window with a 3/4 >> inch piece of Styrofoam insulation and the draft persists (sealed with >> tape around the edges). Seems even a couple of degrees difference with >> the room air can create a draft that is cold enough to be a bother. The >> wall around the window reads 66 degrees while the Styrofoam reads about >> 64 degrees. >> >> I thought maybe the way to deal with the draft is to fight cold with >> fire. So I bought a few power resistors in the metal cases that can be >> mounted. I wired them in series and connected a variable supply as I >> didn't know how much power I would need. Turns out a fair amount. If I >> crank up the heat to around 30 to 40 watts with the resistors right >> behind me on the sill of the window, the draft is gone. Not bad. >> >> But I was wondering how best to mount them. At this wattage they get >> pretty warm, around 200 degrees! I was looking at sheet aluminum to >> mount them to thinking just a couple/three inches of height would do the >> job. But now I am wondering. I'm not sure a string of resistors along >> a three inch wide sheet of aluminum would reduce the temps that much and >> I'm not at all clear on how that might affect the airflow. >> >> I am thinking of a much wider sheet that would not get so hot. I am >> also thinking it would help better to cut the draft by being larger. I'm >> thinking it would give rise to a reverse draft and possibly require less >> heat. >> >> So which is better, a small hotter heat source or a spread out lower >> heat source. I suppose covering the entire windows with aluminum would >> be the best approach, but I'm not ready to do that. So maybe 12 inches >> of aluminum sheet? > > Is it the window or the whole wall? > > I suspect the key idea is "heat output" if it's used properly. If you're > dissipating 50W then you're dissipating 50W and that's your heat flux. > If you spread that flux over a larger area the _temperature_ of your > heating assembly will go down, but not the flow of heat. > > And, I suspect that as long as you maintain the heat output, spreading it > out vertically to reduce the temperature won't change it's effect on the > draft -- you just want to heat the air, you don't care if it happens over > the space of 1/4 inch or ten inches. > > If you just can't get there from here, putting a strip of resistors > inside a cage of chicken wire (or something more decorative) would work > as well as what you have now, with less risk of injury. What I have now *is* a strip of resistors.... Oh, you mean keep the user away from the "high" heat. Eh, I think I'll go with the metal plate. It will look nice and I think it will end up working better to boot. -- Rick C
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| From | Tim Wescott <seemywebsite@myfooter.really> |
|---|---|
| Date | 2017-02-14 17:49 -0600 |
| Message-ID | <hcqdnRjLYrUECj7FnZ2dnUU7-fudnZ2d@giganews.com> |
| In reply to | #447484 |
On Sun, 12 Feb 2017 19:05:02 -0500, rickman wrote: > On 2/12/2017 1:02 PM, Tim Wescott wrote: >> On Sat, 11 Feb 2017 22:02:32 -0500, rickman wrote: >> >>> I sit directly under a window much of the time (don't suggest I move, >>> there just isn't another practical option). When it is cold the >>> window has a draft that is downright brutal. I plugged the window >>> with a 3/4 inch piece of Styrofoam insulation and the draft persists >>> (sealed with tape around the edges). Seems even a couple of degrees >>> difference with the room air can create a draft that is cold enough to >>> be a bother. The wall around the window reads 66 degrees while the >>> Styrofoam reads about 64 degrees. >>> >>> I thought maybe the way to deal with the draft is to fight cold with >>> fire. So I bought a few power resistors in the metal cases that can >>> be mounted. I wired them in series and connected a variable supply as >>> I didn't know how much power I would need. Turns out a fair amount. >>> If I crank up the heat to around 30 to 40 watts with the resistors >>> right behind me on the sill of the window, the draft is gone. Not >>> bad. >>> >>> But I was wondering how best to mount them. At this wattage they get >>> pretty warm, around 200 degrees! I was looking at sheet aluminum to >>> mount them to thinking just a couple/three inches of height would do >>> the job. But now I am wondering. I'm not sure a string of resistors >>> along a three inch wide sheet of aluminum would reduce the temps that >>> much and I'm not at all clear on how that might affect the airflow. >>> >>> I am thinking of a much wider sheet that would not get so hot. I am >>> also thinking it would help better to cut the draft by being larger. >>> I'm thinking it would give rise to a reverse draft and possibly >>> require less heat. >>> >>> So which is better, a small hotter heat source or a spread out lower >>> heat source. I suppose covering the entire windows with aluminum >>> would be the best approach, but I'm not ready to do that. So maybe 12 >>> inches of aluminum sheet? >> >> Is it the window or the whole wall? >> >> I suspect the key idea is "heat output" if it's used properly. If >> you're dissipating 50W then you're dissipating 50W and that's your heat >> flux. If you spread that flux over a larger area the _temperature_ of >> your heating assembly will go down, but not the flow of heat. >> >> And, I suspect that as long as you maintain the heat output, spreading >> it out vertically to reduce the temperature won't change it's effect on >> the draft -- you just want to heat the air, you don't care if it >> happens over the space of 1/4 inch or ten inches. >> >> If you just can't get there from here, putting a strip of resistors >> inside a cage of chicken wire (or something more decorative) would work >> as well as what you have now, with less risk of injury. > > What I have now *is* a strip of resistors.... Oh, you mean keep the > user away from the "high" heat. Eh, I think I'll go with the metal > plate. It will look nice and I think it will end up working better to > boot. I had a brainstorm on this: instead of a strip of resistors and a grille, put a strip of resistors in between two metal plates, with a good amount of spacing in between, and with the slot vertical. Put the resistors toward the bottom. It _should_ create a chimney effect, to get the most air velocity from the power expended by the resistors. Assuming, of course, that's what you actually need. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
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| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-02-12 13:06 -0500 |
| Message-ID | <5v1oA.44296$Ck4.13284@fx44.iad> |
| In reply to | #447363 |
On 02/11/2017 10:02 PM, rickman wrote: > I sit directly under a window much of the time (don't suggest I move, > there just isn't another practical option). When it is cold the window > has a draft that is downright brutal. I plugged the window with a 3/4 > inch piece of Styrofoam insulation and the draft persists (sealed with > tape around the edges). Seems even a couple of degrees difference with > the room air can create a draft that is cold enough to be a bother. The > wall around the window reads 66 degrees while the Styrofoam reads about > 64 degrees. > > I thought maybe the way to deal with the draft is to fight cold with > fire. So I bought a few power resistors in the metal cases that can be > mounted. I wired them in series and connected a variable supply as I > didn't know how much power I would need. Turns out a fair amount. If I > crank up the heat to around 30 to 40 watts with the resistors right > behind me on the sill of the window, the draft is gone. Not bad. > > <snip> So you spend most of your time sitting by a drafty window wired with power resistors? Do people like, call those nice people to check in on you from time to time or...
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-12 19:05 -0500 |
| Message-ID | <o7qt5k$jeh$4@dont-email.me> |
| In reply to | #447433 |
On 2/12/2017 1:06 PM, bitrex wrote: > On 02/11/2017 10:02 PM, rickman wrote: >> I sit directly under a window much of the time (don't suggest I move, >> there just isn't another practical option). When it is cold the window >> has a draft that is downright brutal. I plugged the window with a 3/4 >> inch piece of Styrofoam insulation and the draft persists (sealed with >> tape around the edges). Seems even a couple of degrees difference with >> the room air can create a draft that is cold enough to be a bother. The >> wall around the window reads 66 degrees while the Styrofoam reads about >> 64 degrees. >> >> I thought maybe the way to deal with the draft is to fight cold with >> fire. So I bought a few power resistors in the metal cases that can be >> mounted. I wired them in series and connected a variable supply as I >> didn't know how much power I would need. Turns out a fair amount. If I >> crank up the heat to around 30 to 40 watts with the resistors right >> behind me on the sill of the window, the draft is gone. Not bad. >> >> <snip> > > So you spend most of your time sitting by a drafty window wired with > power resistors? > > Do people like, call those nice people to check in on you from time to > time or... Every hour, on the hour. 8^o -- Rick C
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| From | Clifford Heath <no.spam@please.net> |
|---|---|
| Date | 2017-02-13 11:21 +1100 |
| Message-ID | <58a0fc0c$0$51722$c3e8da3$f6268168@news.astraweb.com> |
| In reply to | #447363 |
On 12/02/17 14:02, rickman wrote: > I sit directly under a window much of the time (don't suggest I move, > there just isn't another practical option). When it is cold the window > has a draft that is downright brutal. Drafts travel along and down walls. I know you said "don't suggest I move", but if you could get even six inches further from the wall, you'd be a lot more comfortable.
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| From | krw@notreal.com |
|---|---|
| Date | 2017-02-12 19:28 -0500 |
| Message-ID | <0cv1ac9drf26s09tirqo5ostilhj5lfleh@4ax.com> |
| In reply to | #447363 |
On Sat, 11 Feb 2017 22:02:32 -0500, rickman <gnuarm@gmail.com> wrote: >I sit directly under a window much of the time (don't suggest I move, >there just isn't another practical option). When it is cold the window >has a draft that is downright brutal. I plugged the window with a 3/4 >inch piece of Styrofoam insulation and the draft persists (sealed with >tape around the edges). Seems even a couple of degrees difference with >the room air can create a draft that is cold enough to be a bother. The >wall around the window reads 66 degrees while the Styrofoam reads about >64 degrees. > >I thought maybe the way to deal with the draft is to fight cold with >fire. So I bought a few power resistors in the metal cases that can be >mounted. I wired them in series and connected a variable supply as I >didn't know how much power I would need. Turns out a fair amount. If I >crank up the heat to around 30 to 40 watts with the resistors right >behind me on the sill of the window, the draft is gone. Not bad. > >But I was wondering how best to mount them. At this wattage they get >pretty warm, around 200 degrees! I was looking at sheet aluminum to >mount them to thinking just a couple/three inches of height would do the >job. But now I am wondering. I'm not sure a string of resistors along >a three inch wide sheet of aluminum would reduce the temps that much and >I'm not at all clear on how that might affect the airflow. > >I am thinking of a much wider sheet that would not get so hot. I am >also thinking it would help better to cut the draft by being larger. >I'm thinking it would give rise to a reverse draft and possibly require >less heat. > >So which is better, a small hotter heat source or a spread out lower >heat source. I suppose covering the entire windows with aluminum would >be the best approach, but I'm not ready to do that. So maybe 12 inches >of aluminum sheet? 3/4" of styrofoam isn't nearly enough. Styrofoam only has an R-value of around 4/in.
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| From | Martin Riddle <martin_ridd@verizon.net> |
|---|---|
| Date | 2017-02-12 21:57 -0500 |
| Message-ID | <is72ac5r4vn4rhf0tc5u3nur0023e3u8ra@4ax.com> |
| In reply to | #447363 |
On Sat, 11 Feb 2017 22:02:32 -0500, rickman <gnuarm@gmail.com> wrote: >I sit directly under a window much of the time (don't suggest I move, >there just isn't another practical option). When it is cold the window >has a draft that is downright brutal. I plugged the window with a 3/4 >inch piece of Styrofoam insulation and the draft persists (sealed with >tape around the edges). Seems even a couple of degrees difference with >the room air can create a draft that is cold enough to be a bother. The >wall around the window reads 66 degrees while the Styrofoam reads about >64 degrees. > >I thought maybe the way to deal with the draft is to fight cold with >fire. So I bought a few power resistors in the metal cases that can be >mounted. I wired them in series and connected a variable supply as I >didn't know how much power I would need. Turns out a fair amount. If I >crank up the heat to around 30 to 40 watts with the resistors right >behind me on the sill of the window, the draft is gone. Not bad. > >But I was wondering how best to mount them. At this wattage they get >pretty warm, around 200 degrees! I was looking at sheet aluminum to >mount them to thinking just a couple/three inches of height would do the >job. But now I am wondering. I'm not sure a string of resistors along >a three inch wide sheet of aluminum would reduce the temps that much and >I'm not at all clear on how that might affect the airflow. > >I am thinking of a much wider sheet that would not get so hot. I am >also thinking it would help better to cut the draft by being larger. >I'm thinking it would give rise to a reverse draft and possibly require >less heat. > >So which is better, a small hotter heat source or a spread out lower >heat source. I suppose covering the entire windows with aluminum would >be the best approach, but I'm not ready to do that. So maybe 12 inches >of aluminum sheet? I'm blessed with 3 huge window panes at work. I use a 10" fan (on the floor) to suck the cool air and move it into the isle, works well. THe temperature stabilizes after about 1/2 hour. Cheers
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| From | "Tim Williams" <tiwill@seventransistorlabs.com> |
|---|---|
| Date | 2017-02-13 10:01 -0600 |
| Message-ID | <o7sl4u$ck0$1@dont-email.me> |
| In reply to | #447519 |
"Martin Riddle" <martin_ridd@verizon.net> wrote in message news:is72ac5r4vn4rhf0tc5u3nur0023e3u8ra@4ax.com... > I'm blessed with 3 huge window panes at work. > I use a 10" fan (on the floor) to suck the cool air and move it into > the isle, works well. > THe temperature stabilizes after about 1/2 hour. Good point -- I've found in my poorly heated apartment, I need to encourage convection to keep the temperature even. A fan pointed at the top of the window bank (or away at the bottom, as in your case) does wonders, despite increasing the air currents overall. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
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| From | Lasse Langwadt Christensen <langwadt@fonz.dk> |
|---|---|
| Date | 2017-02-13 13:49 -0800 |
| Message-ID | <6f9c7707-2170-48b9-9707-040a654ede2a@googlegroups.com> |
| In reply to | #447363 |
Den søndag den 12. februar 2017 kl. 04.02.37 UTC+1 skrev rickman: > I sit directly under a window much of the time (don't suggest I move, > there just isn't another practical option). When it is cold the window > has a draft that is downright brutal. I plugged the window with a 3/4 > inch piece of Styrofoam insulation and the draft persists (sealed with > tape around the edges). Seems even a couple of degrees difference with > the room air can create a draft that is cold enough to be a bother. The > wall around the window reads 66 degrees while the Styrofoam reads about > 64 degrees. > > I thought maybe the way to deal with the draft is to fight cold with > fire. So I bought a few power resistors in the metal cases that can be > mounted. I wired them in series and connected a variable supply as I > didn't know how much power I would need. Turns out a fair amount. If I > crank up the heat to around 30 to 40 watts with the resistors right > behind me on the sill of the window, the draft is gone. Not bad. > > But I was wondering how best to mount them. At this wattage they get > pretty warm, around 200 degrees! I was looking at sheet aluminum to > mount them to thinking just a couple/three inches of height would do the > job. But now I am wondering. I'm not sure a string of resistors along > a three inch wide sheet of aluminum would reduce the temps that much and > I'm not at all clear on how that might affect the airflow. > > I am thinking of a much wider sheet that would not get so hot. I am > also thinking it would help better to cut the draft by being larger. > I'm thinking it would give rise to a reverse draft and possibly require > less heat. > > So which is better, a small hotter heat source or a spread out lower > heat source. I suppose covering the entire windows with aluminum would > be the best approach, but I'm not ready to do that. So maybe 12 inches > of aluminum sheet? > don't forget to look at the datasheet for those resistors, quite a few of them will be derated to ~0W at ~100'C
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-13 20:36 -0500 |
| Message-ID | <o7tms6$8nh$2@dont-email.me> |
| In reply to | #447597 |
On 2/13/2017 4:49 PM, Lasse Langwadt Christensen wrote: > Den søndag den 12. februar 2017 kl. 04.02.37 UTC+1 skrev rickman: >> I sit directly under a window much of the time (don't suggest I move, >> there just isn't another practical option). When it is cold the window >> has a draft that is downright brutal. I plugged the window with a 3/4 >> inch piece of Styrofoam insulation and the draft persists (sealed with >> tape around the edges). Seems even a couple of degrees difference with >> the room air can create a draft that is cold enough to be a bother. The >> wall around the window reads 66 degrees while the Styrofoam reads about >> 64 degrees. >> >> I thought maybe the way to deal with the draft is to fight cold with >> fire. So I bought a few power resistors in the metal cases that can be >> mounted. I wired them in series and connected a variable supply as I >> didn't know how much power I would need. Turns out a fair amount. If I >> crank up the heat to around 30 to 40 watts with the resistors right >> behind me on the sill of the window, the draft is gone. Not bad. >> >> But I was wondering how best to mount them. At this wattage they get >> pretty warm, around 200 degrees! I was looking at sheet aluminum to >> mount them to thinking just a couple/three inches of height would do the >> job. But now I am wondering. I'm not sure a string of resistors along >> a three inch wide sheet of aluminum would reduce the temps that much and >> I'm not at all clear on how that might affect the airflow. >> >> I am thinking of a much wider sheet that would not get so hot. I am >> also thinking it would help better to cut the draft by being larger. >> I'm thinking it would give rise to a reverse draft and possibly require >> less heat. >> >> So which is better, a small hotter heat source or a spread out lower >> heat source. I suppose covering the entire windows with aluminum would >> be the best approach, but I'm not ready to do that. So maybe 12 inches >> of aluminum sheet? >> > > don't forget to look at the datasheet for those resistors, quite a few > of them will be derated to ~0W at ~100'C I think that would be 100°C ambient temperature, not the resistor. They don't want the resistor going above 100°C perhaps, but that doesn't mean you can't put power in to reach that temp. -- Rick C
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-01 19:44 -0500 |
| Message-ID | <o97pp0$59v$1@dont-email.me> |
| In reply to | #447363 |
On 2/11/2017 10:02 PM, rickman wrote: > I sit directly under a window much of the time (don't suggest I move, > there just isn't another practical option). When it is cold the window > has a draft that is downright brutal. I plugged the window with a 3/4 > inch piece of Styrofoam insulation and the draft persists (sealed with > tape around the edges). Seems even a couple of degrees difference with > the room air can create a draft that is cold enough to be a bother. The > wall around the window reads 66 degrees while the Styrofoam reads about > 64 degrees. > > I thought maybe the way to deal with the draft is to fight cold with > fire. So I bought a few power resistors in the metal cases that can be > mounted. I wired them in series and connected a variable supply as I > didn't know how much power I would need. Turns out a fair amount. If I > crank up the heat to around 30 to 40 watts with the resistors right > behind me on the sill of the window, the draft is gone. Not bad. > > But I was wondering how best to mount them. At this wattage they get > pretty warm, around 200 degrees! I was looking at sheet aluminum to > mount them to thinking just a couple/three inches of height would do the > job. But now I am wondering. I'm not sure a string of resistors along > a three inch wide sheet of aluminum would reduce the temps that much and > I'm not at all clear on how that might affect the airflow. > > I am thinking of a much wider sheet that would not get so hot. I am > also thinking it would help better to cut the draft by being larger. I'm > thinking it would give rise to a reverse draft and possibly require less > heat. > > So which is better, a small hotter heat source or a spread out lower > heat source. I suppose covering the entire windows with aluminum would > be the best approach, but I'm not ready to do that. So maybe 12 inches > of aluminum sheet? So I got the power supply in and hooked it up. This is a laptop type supply with a switch for 12 to 24 volts output. Driving a 10 ohm load that produces 14.4 to 57.6 watts. With the old unit at 20 volts it was more than warm enough for a cold night. This one will surely do the job if it doesn't blow up. I ordered more resistors which I will connect to get a 6 ohm load for the full rated 96 watts. We'll see if the power pack dies with that high a load. There are some colds nights ahead in spite of the present 70 degree days. Very strange weather for February. The supply is about the same size as my Toshiba brick, but MUCH lighter, so obviously not so much magnetics. I wonder what the quality is like inside? How would you make a 96 watt DC power supply that weighs less than 6 oz including the corded EMI filter? -- Rick C
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| From | George Herold <gherold@teachspin.com> |
|---|---|
| Date | 2017-03-01 17:33 -0800 |
| Message-ID | <631fc068-de02-4463-9b34-dc240354c4ca@googlegroups.com> |
| In reply to | #449786 |
On Wednesday, March 1, 2017 at 7:44:09 PM UTC-5, rickman wrote: > On 2/11/2017 10:02 PM, rickman wrote: > > I sit directly under a window much of the time (don't suggest I move, > > there just isn't another practical option). When it is cold the window > > has a draft that is downright brutal. I plugged the window with a 3/4 > > inch piece of Styrofoam insulation and the draft persists (sealed with > > tape around the edges). Seems even a couple of degrees difference with > > the room air can create a draft that is cold enough to be a bother. The > > wall around the window reads 66 degrees while the Styrofoam reads about > > 64 degrees. > > > > I thought maybe the way to deal with the draft is to fight cold with > > fire. So I bought a few power resistors in the metal cases that can be > > mounted. I wired them in series and connected a variable supply as I > > didn't know how much power I would need. Turns out a fair amount. If I > > crank up the heat to around 30 to 40 watts with the resistors right > > behind me on the sill of the window, the draft is gone. Not bad. > > > > But I was wondering how best to mount them. At this wattage they get > > pretty warm, around 200 degrees! I was looking at sheet aluminum to > > mount them to thinking just a couple/three inches of height would do the > > job. But now I am wondering. I'm not sure a string of resistors along > > a three inch wide sheet of aluminum would reduce the temps that much and > > I'm not at all clear on how that might affect the airflow. > > > > I am thinking of a much wider sheet that would not get so hot. I am > > also thinking it would help better to cut the draft by being larger. I'm > > thinking it would give rise to a reverse draft and possibly require less > > heat. > > > > So which is better, a small hotter heat source or a spread out lower > > heat source. I suppose covering the entire windows with aluminum would > > be the best approach, but I'm not ready to do that. So maybe 12 inches > > of aluminum sheet? > > So I got the power supply in and hooked it up. This is a laptop type > supply with a switch for 12 to 24 volts output. Driving a 10 ohm load > that produces 14.4 to 57.6 watts. With the old unit at 20 volts it was > more than warm enough for a cold night. This one will surely do the job > if it doesn't blow up. I ordered more resistors which I will connect to > get a 6 ohm load for the full rated 96 watts. We'll see if the power > pack dies with that high a load. There are some colds nights ahead in > spite of the present 70 degree days. Very strange weather for February. Spring came early this year... Late Feb and we have wood cocks, black birds, and robins all back... well only the males. :^) George H. > > The supply is about the same size as my Toshiba brick, but MUCH lighter, > so obviously not so much magnetics. I wonder what the quality is like > inside? How would you make a 96 watt DC power supply that weighs less > than 6 oz including the corded EMI filter? > > -- > > Rick C
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