I have been testing out a modified chiller now for two weeks and find that my ( this is May-2004) system is less than 2 gallons of water high Tamp Florida Humidity and I am not in the summer yet. I can say that so far I am very happy with the results so far. I am using a 1/4 hp chiller

First test done:

the temp was 72 and humidity 82%  I ran the 10xe with no secondary cooler and got to -5 94%  Turned on the chiller and set the water to 39 degrees the chiller says it will go down to 32 though with that humidity and the lines not being insulated I did not go that low The chip cooled to - 15 and I ran it all night that way. In the morning it was a nice 70 by the scope, and humidity in the observatory was 86% chip still at -15 and 90%
Now this was not done as a bench test and the hoses running to the camera were 8' long each one. The whole system has 20' of line 1/2" tubing was used. And the camera ran from midnight to 6:30am taking images all night.  Did not want the camera to be idle when I tested this Since my secondary cooler has not worked since early last year I was not able to get the camera lower than -5 and even 0 all last summer.  am using the Particle Wave desiccant plug and saw no frosting in the camera or the sub frames.  The tubes did have moisture on them and there was evidence of dripping from the tubes on the indoor-outdoor carpet that I have in the observatory.  When I moved the mount to park1 position ( AP mount) there was allot of dripping occurring from the camera area, though when I walked over to the cameras I did not notice anything weird. This was also at 6:30am after a full night of dew too, so the scopes could have also caused that dripping to happen too.  All in all I think that if I wrapped the lines and reservoir with insulation I might just be able to get another 5 degrees colder?   Maybe not sure on that one. The condensation on the lines would definitely stop though


System being run:

The whole system will be running 1/2" tubing and at the camera there are two reducers down to the 1/4" to go into the camera

Ehiem 1250 pump
http://www.dangerden.com/images/pumps/e1250l.gif

Chiller
http://www.aquastealth.com/index.asp?PageAction=VIEWCATS&Category=245

Reservoir
http://www.dangerden.com/mall/Misc_Hardware/round.asp


You are welcome and will try and answer any questions you may have

1)How long does the chiller take to get to below 40?
I have not been able to get the chiller lower than 35 degrees as of yet and
the ambient temp last night was down to 61 degrees at the lowest. I am
using very little fluid in my system a total of 20' of 1/2" tubing the water
pump, the chiller, and a small reservoir that might hold 10 oz. I put 8 oz
of isopropyl alcohol in this system the rest tap water. Last night when I
started at ambient temp of 65 I had the chiller down to 40 degrees within 35
min. That was my set point then I tried to go lower from there and could
not get it lower than the 35.5 degrees
Humidity last night was 90%

2)Do I need to pre-cool the water or is it pretty fast?
I do not, I leave everything hooked up in my observatory and the temp gauge
in there said that yesterday's high was 94 in the observatory. There really
is not allot of fluid in the system that I am running

3)Have you considered the overclocker technique of using the cooling fluid
designed to work in a PC? Not sure it adds anything but a bit of
anti-freeze.
Just use the Isopropyl as stated

4)On insulating the lines
Thought about it have not acted yet

5)Do you leave the hoses connected after shutdown or do you drain? I
am considering fast connects that seal when disconnected to keep the
system full but without the hoses hanging about.
I leave the system hooked up. I tried the quick disconnects then had
something hanging from the camera. Since I have a 1/4" to 1/2" adaptor on
the camera end I pull the line off the camera and use a 1/4" to 1/4 connect
both ends to one another and the system is still closed and disconnected. I
can then pull apart and hook up and the reservoir takes out any air that
might have gotten in the system.

6) As when parking the mount (AP too) I use #1 position which would move
the hoses quite a bit from say imaging to the south. Ahh more
electronic gear....
I did not skimp on the length of hose that I am using. The small reservoir
sits on the lower shelf of my AP pier tables I have a two tier one. The
chiller sits under that and the Eheim pump sits next to that. So the
reservoir is higher than the chiller and pump yet lower than the camera. I
can slew anywhere in the sky and not worry about the hoses. Though if I was
doing a mapping run I would disconnect this system The hose that connects
the camera 1/4" to the 1/4" to 1/2" hose is so short that the adaptors 1/4"
end is just about touching the 1/4" nipple that extends out of the SBIG
camera. This way I get very minimal crimping of the line since the 1/4"
line is the smallest in this set-up and really isonly there to connect the
adaptor to the camera.

Hope this helps

Last night once again this has happened When I get the camera down to -20 everything is fine ( NO secondary cooler running Ambient temp last night 61) Power on camera reading 80% so I reduced it down to -25 like the night before and all hell broke loose. The temp reading on the camera dropped to - 153.6 and could not get the reading to change. Two nights ago I closed up shop and went to bed. Last night I said no big deal left the temp setting to -25 did not care what the reading on the program was saying. Set up a sequence to image and did darks with the lights. When I got back to the observatory in morning it was reading -25 and the camera setting was -25. My images were reading -25, and the darks too. ONLY the fist 1200 sec image read -153.6 as my temp So camera went to - 9 90% ambient temp 64 25 91% ambient temp 60 Chiller water reading 35.5 degrees
 
The above problem was something wrong in the camera.  After talking with SBIG I shipped the camera back and a part was replaced.  I can not remember the name of the part though.  I wrote this so that if anyone gets these weird temp reading they know that there is something wrong with the camera and SBIG will know exactly what is wrong.

UPDATE

I ran this system now all summer long and it is now December.  When the camera went back to SBIG for the fix I also had them fix the Secondary cooler for this camera.  All summer long I was imaging at -20 or -25 depending on how hot it was and the humidity.  The Secondary cooler gave me an extra 8 degrees in the Summer and the chiller gave me about another 18 or so degrees.  When I pushed the system I was able to get the chip down to -40 in the summer time.  However the moisture on the camera was unruly.  And this temperature was really not obtainable then it was 75 outside with humidity of 98%.  I never did insulate the lines.  But what I did end up doing was placing a Dew Heater strip around the camera.  I placed it loosely around there the camera and filter wheel meet.   I did this because in the humid summer months the camera was dripping with water.  I figured not a good thing.  I place the heater element on low ( I can control how long this element cycles thanks to the new Kendrick Dew Controller)  I get no dew or moisture on the camera anymore, and now that it is getting colder I am down to -35 now where I only dreamed about that temperature in the odd very very cold nights.  I can not wait to see the first night under 58 degrees outside.  I bet I can get to -45 and really frost things up