gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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97F today... reflectix experiment
#5280234 - 06/20/12 07:50 AM Attachment (52 downloads)
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I've been meaning to do this for a long time. Temps are forecasted to approach 100 today and with the Max inside temperature reaching 10-15F above the high for the day on sunny days (despite not being in direct sun in the afternoon) I wanted to see what effect the reflectix would have. Yes I know it is supposed to go on the inside but this is the quicker experiment. On cloudy days there is no bad heat rise so I know my problem is pre-2pm sun exposure.
My pod walls are insulated and the bays have the black lining. I paid probably $500 extra for that.
This is a 4 foot wide (tall in this application) 25 foot roll (half of it is still rolled up on the left side of the picture) that was 39.98 at Lowes.
I am covering the south facing pod walls and bays here. In the morning sun despite being only 70F right now the tan walls were starting to get warm.
Edited by gillmj24 (06/20/12 08:01 AM)
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280237 - 06/20/12 07:55 AM Attachment (32 downloads)
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Its 76.6 inside my kitchen at the moment, 70.7 F and 85% humidity in the observatory.
Yesterdays observatory temperature range (pre-reflectix) was 66.9F to 87.9F since it was cloudy in the morning and the official high of the day was about 82. That bottom.right number is what I will be checking when i get home from work today
Right now my local weather underground reporting station says 74F there. Since taking the picture the observatory temperature is up to 71.0F. That thermometer is mounted on the white exploradome ring, above the pod walls near the door on this south facing side.
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mattw
sage
Reged: 07/19/06
Loc: Arkansas
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280261 - 06/20/12 08:20 AM
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I will be very interested in your results.
It's really supposed to go on the inside?
It reflects UV?
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dobsoscope
sage
Reged: 05/24/06
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Re: 97F today... reflectix experiment
[Re: mattw]
#5280362 - 06/20/12 09:48 AM
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If you put it on the inside the external fabric of the observatory would have already absorbed the sun's radiant heat.
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Bob Griffiths
Getting Grouchy
Reged: 10/10/05
Loc: Frederick Maryland
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Re: 97F today... reflectix experiment
[Re: mattw]
#5280376 - 06/20/12 09:55 AM
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Is your ED dome coated black inside...??? Just curious ...
My ED is on a 10x10 building no insulation but paneled inside and NOT black lined
it normally runs 3 degrees hotter then the ambient ..
Just checked the interior of mine is now (at 9:47 AM) 80.3 ... Ambient Temp is 83.6 ..By 3 PM I expect the interior to be 3 degrees ABOVE Ambient..
Bob G,
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: Bob Griffiths]
#5280404 - 06/20/12 10:16 AM Attachment (34 downloads)
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Yes my dome is black lined.
Looks like with summer solstice and the sun rising in the northeast, the reflectix.will need to cover all the pod bays to mean anything. Temperature already 92 inside at 940am
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280409 - 06/20/12 10:17 AM Attachment (29 downloads)
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Thermometer
Edited by gillmj24 (06/20/12 10:22 AM)
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280411 - 06/20/12 10:18 AM Attachment (24 downloads)
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My north facing bays are getting some solar radiation.
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280415 - 06/20/12 10:19 AM
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Tonight I can pit more reflectix to cover all bays, or remove it completely. In the name of science, which makes for a better experiment? I already know my Max temp has been in the 110-115 range so trying to duplicate that isn't adding much info.
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csa/montana
Den Mama
Reged: 05/14/05
Loc: montana
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280421 - 06/20/12 10:23 AM
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Quote:
Tonight I can pit more reflectix to cover all bays, or remove it completely.
As long as you already have the material, why not cover all the bays to see what difference it may make? 
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: csa/montana]
#5280467 - 06/20/12 10:52 AM
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I assumed the reflectix went inside. Lots of people talked about it but I have never seen pictures of a pod with reflectix.
In a traditional use like an attic the reflectix goes on the 2x4's beneath the roof. You aren't supposed to cover the roof exterior with it - though that would be better right? It prevents the 160 Degree shingles from RADIATING to the rest of the attic. It does not prevent conductive or convective heat transfer only radiative. Once those black lined bays get hot they radiate inside the dome..the white exploradome is also black lined but I never felt as though I could fry an egg on the dome exterior like it did when touching the outside of the pod bays.
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Mirzam
Post Laureate
Reged: 04/01/08
Loc: Lovettsville, VA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5280587 - 06/20/12 11:54 AM
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The shiny surface of the reflectrix has low emissivity--meaning that it does not emit heat readily from the aluminum coated surface. The surface also has high reflectance, which means that it reflects both visible light and heat away from the surface.
So by putting the reflectrix in an attic beneath the roof trusses any heat that is transmitted through the roof into the attic space is reflected back towards the roof, and the shiny surface facing into the attic has the already mentioned limited emissivity. There is also a bubble layer between the aluminized surfaces to provide a bit of conductive barrier. The best way to install the stuff is to attach it to the inward facing edges of the trusses, leaving channels between the trusses open to airflow that connects to a ridge vent that permits the hot air between the reflectrix and the roof sheathing to escape.
The outside of the observatory should be reflective to avoid as much heating as possible in the first place. If you have enough power, a small window AC unit could be used to get the temperature down to the expected nightime range a few hours before opening things up for observing.
JimC
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: Mirzam]
#5280699 - 06/20/12 12:40 PM
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I bought an AC unit yesterday, the portable kind so that I just have to make a smallish hole in the bay to install the vent hose. I will cover the vent output with screen material so that no bugs get in there. Any best practices/tools or cutting the bays? I can make a 1.5" hole with a drill, then hacksaw if that sounds right.
Wife said the temp read 102 when it's officially 92 at my local weather station (in the shade of course) about 30 minutes ago.
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mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281003 - 06/20/12 04:42 PM
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A hacksaw works on the POD material, but a little jigsaw also works very well especially when cutting tighter radius curves. I've tried a variety of blades and found a mid range blade (not the most aggressive wood blade and not the finest metal cutting blade) works very well.
The bays which are single walled and are very easy to cut through with this method.
I know this is because I've recently added some forced air cooling to my POD. A little bathroom vent fan and cheap plastic vent kit is pulling cool air from under the platform and into the POD. The vent is on the side of one of the POD bays.
This idea is working out reasonably well but the POD dome really traps hot air up high. I'm looking at options to more easily displace this hot air.
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: mclewis1]
#5281135 - 06/20/12 06:14 PM
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107 was the inside high today. I think the reflectix on the south side helped. I expected worse.
Currently it is 95 in the Obs and that is roughly ambient right now. It has been in the shade for a couple hours.
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281877 - 06/21/12 07:57 AM Attachment (19 downloads)
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This morning I used my 2 foot wide roll of reflectix to cover the east and north facing bays. I also cracked open the upper shutter, at which point a couple wasps appeared 
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281880 - 06/21/12 08:01 AM Attachment (22 downloads)
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The bays are right up against the deck railing so there isn't much room.to.do better than this. This should only see sun in the morning but the sun is high enough now that the dome might not block it.
You can also see where I used expanding foam to seal the holes between the pod wall tops and the exploradome mounting ring. On the inside it is pale yellow but where it is exposed to the elements it is gross orange color.
Edited by gillmj24 (06/21/12 08:26 AM)
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281881 - 06/21/12 08:01 AM Attachment (18 downloads)
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Deck railing
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281883 - 06/21/12 08:04 AM Attachment (17 downloads)
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Today's forecast is 99. Tomorrow is lower 90s but chance of showers so I think I will close the open shutter after today's experiment.
Someone on the pod yahoogroups said they made pvc frames to stand and block the bays and covered this with reflective liner.
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gillmj24
Post Laureate
Reged: 12/06/05
Loc: PA
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Re: 97F today... reflectix experiment
[Re: gillmj24]
#5281885 - 06/21/12 08:04 AM
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At 8:04 it is 76, and the weather station is reporting 81.
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