Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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I'm curious about something... A dome vendor claimed that "small shuttered observatories" will "be unusable for 4-5 months out of the year" because of "chimney effect" that their competing product won't experience. This "chimney effect" I guess this is supposed to be heat rising from inside the dome will make viewing impossible.
The statement seems a little 'drastic' but I'm curious if there is such a thing that could cause issues? 
It's starting to turn cold here in Wisconsin. Last night when I closed down it was 22 degrees and a very slight wind blowing. Last night I was treated to one of the most stunning views I have ever had of Mars, so I was in the obs most of the night. Besides having dew heaters on the corrector plate, diagonal and binoviewer EP's I also run a heated vest under my snowmobile suit. I would think with all that there should be some of this "chimney effect" yet I noticed nothing but a beautiful view of Mars, the surface features, polar cap, colors, shades, it was beautiful. There was some occasional 'swimming' of the image (I was 2Xbarlowed with a pair of D14's in the binoviewers) but didn't notice anything out of the ordinary. If anything, I think the view was so good because the mirror was fully stabilized being in the dome rather than being hauled out of the warm house. A dome is good.
So where is this "chimney effect"? Does it only happen at sub-zero temperatures or something? Does it need to be humid or dry or something? Windy? Calm?
Has anyone ever experienced this, particulary with an ExploraDome? I want to know what to expect, (if anything) as we come into well below freezing temperatures at night.
Thanks for any input.
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Jim W Astro images
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rodney
Vendor - Explora Dome
Reged: 03/08/05
Posts: 1306
Loc: Asbury, NJ
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Jim,
I think that chimney effect is from those older coal burning mounts!!! HA HA. It was 21 degrees here the other night and my views were spectacular, and I base that on when I would set up on the patio before. 4-5 months out of the year, that does seem drastic. I know that the professional observatories limit the amount of people in the dome at any one time. I think I saw online a pic of an Pro Obs in Hawaii that had a unique approach to this effect. The walls under the dome opened up to allow the temps to equal out. It would do nothing from what I saw as to the chimney effect rising up from what I assume is body heat. Open walls will not stop the rising heat from whatever source. If anything it will push the heat from the source out the slot of the dome more. Heat rises.
Either way my viewing in the past 8 months has tripled and that is the best part.
Clear skies,
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Explora Dome information can be found here:
www.exploradome.us
Rodney
13 Truss
Canon XSi
Extremely happy Explora Dome home observatory owner
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Scott Horstman
Vendor - Backyard Observatories
Reged: 03/11/04
Posts: 13088
Loc: Too Far North, USA
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Quote:
A dome vendor claimed that "small shuttered observatories" will "be unusable for 4-5 months out of the year"
I don't know who would think people are so gullible that they would say that. I've been imaging from my dome for a long time now and I've never had any issues with any chimney effect.
If I know I'm going out for the evening I open the observatory near sunset and by the time I get out there everything is acclimated. I also think the wind block is mandatory. I can image in 15-20 mph winds plus if it's cold I'm protected and I'm getting to really not like the cold in my old age.
I do all my imaging from the dome and visual from one of the roll-off's.
If this were actually an issue I'd guess the slotted domes would not be the design of choice for professional observatories around the world.
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SometimesKen
professor emeritus
Reged: 07/15/05
Posts: 579
Loc: Bad Moon Observatory
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Hi Jim,
I've been using my ED since Feb.'07 and have not noticed anything I would call "Chimney effect" . On a few very cold nights (15* or less) I used a small radiant heater in the obs. to keep my tootsies warm and laptop running and still did not notice anything that detracted from my views. I guess if you tried to keep the obs. at a constant 70* you would notice something.
Ken
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Bad Moon Observatory - February 1, 2007
Edited by Snaproll (11/16/07 05:34 PM)
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Quote:
If this were actually an issue I'd guess the slotted domes would not be the design of choice for professional observatories around the world.
I think "the deal" the vendor was talking about were "small" shuttered observatories having the problem.
I agree, my experience is to open the dome early in the evening before I go out. Kind of air it out sort of speak. I generally leave all the gear set up, and a couple night ago I was doing visual and noticed that the EPs were fogging from the heat of my head, so last night I turned on all the heaters when I opened the dome and didn't have any fogging issues with the EPs.
I haven't used my dome yet in winter but I know others have been using the ExploraDome for over a year. I figure if there is any real issue it would have come out by now, so I wanted to check experiences of those that have been using them through a winter already.
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Jim W Astro images
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Quote:
I used a small radiant heater in the obs. to keep my tootsies warm and laptop running and still did not notice anything that detracted from my views.
Thanks Ken. One thought for ya, I use a heated motorcycle vest I plug into the pier. That keeps the heat inside the snowsuit and keeps my core warm so I think it works pretty well. On the PC, I used to image out in the open so I built a box that is insulated with a lexan cover. Just the laptop or STV generates enough heat to keep it alive. On real cold night I toss in a couple of heat packs to be sure.
Thanks for the input. That's what I'm looking for, those with experience in the winter so I know what to expect.
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Jim W Astro images
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Scott Horstman
Vendor - Backyard Observatories
Reged: 03/11/04
Posts: 13088
Loc: Too Far North, USA
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Quote:
I think "the deal" the vendor was talking about were "small" shuttered observatories having the problem.
Slot sizes are in porportion with the building size. And also the activities going on and equipment inside. I'm not sure there would be a difference.
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Scott
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane."
Marcus Aurelius (AD 121-180)
www.backyardobservatories.com
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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I've been trying to wrap my pea size brain around the "chimney effect" statement since I first read it a few weeks ago. Can't do it. I thought at first it might be due to the small size of my brain, but I've realized it's more to do with the HUGENESS of the statement. It is a HUGELY non existent effect.
This will be the second complete winter of activity in my ED and I've not EVER experienced any chimney effect. The nights that have been -20 degrees might have welcomed enough heat to have caused the effect, but alas....
Edited by Snaproll (11/16/07 06:02 PM)
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Have you had any issues with freezing or ice? Anything with the shutter freezing up or the dome's rotation?
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Jim W Astro images
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Quote:
Slot sizes are in porportion with the building size. And also the activities going on and equipment inside. I'm not sure there would be a difference.
Well, a larger dome would have more volume of air and a larger area for the heat to disperse. A smaller dome would have more concentration of heat.
The shutter seems large enough that any heat should rise and escape fairly quickly I would think.
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Jim W Astro images
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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Quote:
Have you had any issues with freezing or ice? Anything with the shutter freezing up or the dome's rotation?
You've the fastest keyboard in the East!!!(private joke)
Issues with freezing or ice??? Yes, I noticed just yesterday the snow had kind of froze to the top of the dome. When I opened the shutter, it acted just like a window scraper and simply pushed the offending snow and ice off the dome. No, as a matter of fact, I've put my hands on a reversible winch, and I'm considering mounting it OUTSIDE the dome, on the side of the attached warm room, with a cable wrapped around the winch drum several times, and around the dome 1.25 times. This ought to nallow me to rotate the dome with power from a 12 volt source instead of pushing it from the inside.
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IF YOU COULD SEE FROM WHENCE YOU CAME YOU WOULD KNOW WHERE YOU'RE GOING TOO.
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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Quote:
Quote:
Slot sizes are in porportion with the building size. And also the activities going on and equipment inside. I'm not sure there would be a difference.
Well, a larger dome would have more volume of air and a larger area for the heat to disperse. A smaller dome would have more concentration of heat.
The shutter seems large enough that any heat should rise and escape fairly quickly I would think.
The thing being missed here, is that there is not enough heat to cause the effect in the first place in such a large area, and in this case, the ED is a large area.
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IF YOU COULD SEE FROM WHENCE YOU CAME YOU WOULD KNOW WHERE YOU'RE GOING TOO.
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Quote:
This ought to allow me to rotate the dome with power from a 12 volt source instead of pushing it from the inside.
The rotation motor I have with the white ED is beautiful! Really slick.
Why a 12V power source? No power 120V at your observatory?
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Jim W Astro images
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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The winch is 12 volt. It's originally used as a plow lift on the front of a ATV. The dome rotates with such ease, I'm thinking it will not take a 12 Horsepower, unlimited torgue motor.
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IF YOU COULD SEE FROM WHENCE YOU CAME YOU WOULD KNOW WHERE YOU'RE GOING TOO.
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Scott Horstman
Vendor - Backyard Observatories
Reged: 03/11/04
Posts: 13088
Loc: Too Far North, USA
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I suppose that could be an area of study if one were so inclined. All I can say from experience is that I've not been affected by this. My NE Ohio sky is my biggest bummer.
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Scott
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane."
Marcus Aurelius (AD 121-180)
www.backyardobservatories.com
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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Quote:
I suppose that could be an area of study if one were so inclined. All I can say from experience is that I've not been affected by this. My NE Ohio sky is my biggest bummer.
Mine too!! Knowing that all the weather you get rolls by here 24 or so hours later.
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IF YOU COULD SEE FROM WHENCE YOU CAME YOU WOULD KNOW WHERE YOU'RE GOING TOO.
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Bob Griffiths
Getting Grouchy
Reged: 10/10/05
Posts: 10103
Loc: Frederick Maryland
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Well I HAVE used my ED for ONE full winter (I put it in use Sept 12th of 2006)..
I also use a heated Motorcycle jacket liner Under a zip up sweat shirt or a heavier regular jacket and I use a pair of heated socks that plug into the jacket liner
( www.heatedclothing4you.com )
I am a visual observer...BUT last winter I had absolutely no problems with any heat currents screwing up my views.. NONE...ZILCH yet I was nice and warm and out of the cold breeze,as the jacket maintains a temp of 101 or 102 against my t-shirt..
I figure I was putting out as much hot air into the obs and out the shutter as I would have been if I were running a good fever.
I imagine that in extremely cold environments like maybe minus 40 my body would throw off enough heat to be a slight problem but if it were that cold I do not think I could be able to walk outside and climb into my observatory...
ON THE ICE.....OH YES!
I learned the hard way.
We had all of 2 inches of WET snow early last winter, Sun melted most of the snow BUT a good 1/2 inch refroze the next night ... Any lazy me did not brush it off as 2" of NORMAL snow is absolutely nothing, this was REAL HEAVY WET SNOW.
DUH my dome was frozen in place .. (ice covered the top of the roof panel and up onto the lip of the dome itself) The shutter however opened just fine !
After that experience I learned to handle my DOME like I do my driveway...
I just walk outside the next morning or afternoon with a broom and brush all the snow away from the domes skirt. THEN rotate the dome itself a couple of times..
Most of the time the dome itself was completely free of snow the following morning BUT I still made sure the skirt was clear of any snow on top of the roof panels.. We di not have a lot of snow last winter but I never had any problems
after the first snow/ice storm.
With a round dome you have no
roof for snow to lay on so you should not have any problem I would brush off the shutters rear tracks however...only takes a minute
Bob G.
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CPC1100
Nexstar 8i + GPS & Rays Brackets
Denk S1 power switch
Orion 100 mm Refractor
Meade LXD 55 ...AR-5 127 mm Refractor
Gerbring heated clothing in the winter
Exploradome Observatory S.I.E. (Smiling Irish Eyes)
39*21'03" N
77*28'12" W
The sky over my head....
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Snaproll
Postmaster
Reged: 02/20/04
Posts: 5095
Loc: Green Bay
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Good information Bob, and thanks everyone. The input is appreciated, I have an idea what to expect.
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Jim W Astro images
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Starman27
Carpal Tunnel
Reged: 01/29/06
Posts: 2865
Loc: Illinois, Iowa
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Hi all,
remember when Mars was really close? I waited close to four hours to see Mars in one of the Peoria Astronomical Socities telescopes. It is a 9.5 inch refractor in an old observatory. The observatory is large and has a large shuttere. Larger than a whole half an ED.
Wjhile standing in line I had the opportunity to view Mars through many of the club's telescopes (many APs., but none over 5 inches). Absolutely great views. At 3:30 a I finally got into the observatory. I looked through the refrector and guess what? "Chimeny effect". The heat from the people in the observatory dome was flying out the open slit and distorting the view. Most disappointing. It sure wasn't hard to get my mind around it. I just had to look throiugh the telescope instead of image through it. The comparison between the scopes outside and the much larger one in the observatory was clear. BTW as a stucent (a long time ago) I have used up to a 12 inch refractor in a large dome. The same effect was there occasionally even though the dome was much larger.
Just my experiences.
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Enjoy the dark,
Herman
Illinois ROR
Iowa Skyshed POD
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rodney
Vendor - Explora Dome
Reged: 03/08/05
Posts: 1306
Loc: Asbury, NJ
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Steve,
That brings back some memories way back in 1984 during the Halley return. I was using the 12 inch refractor at the local community college down in Maryland where I used to live. The dome was an old silo top with a roll up shutter. As you can imagine we had quite a few people through the observatory on a number of nights and I can recall never having any seeing issues due to the heat from the people present. The dome had to be at least 15 feet across, and the club/college only allowed x-amount of people on the observing deck at any one time, for insurance purposes no doubt. So with the PC (yep we had a TRS-80 back then) guy and the scope operator we would have maybe 8 extra bodies in the observatory with no ill effects. It makes me wonder why the big professionals use "domes" over any other designs?
Clear skies,
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Explora Dome information can be found here:
www.exploradome.us
Rodney
13 Truss
Canon XSi
Extremely happy Explora Dome home observatory owner
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