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Old 07-11-2011, 02:54 AM
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pmrid (Peter)
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Water-Cooling the CCD

One of my cameras has a facility to supplement cooling by means of a water flow. It's an ATIK 11002M. The normal capability of the cooler is a max of 38 below delta. With water cooling it is said to be capable of going another 10.
During the cooler months, setting the temp to -20 was feasible most nights and on several, it would have been possible to go to -30 but summer is obviously going to challenge those settings - particularly if you hope to run the cooler at something less than 100% all the time.

So my thoughts have turned to the possibility of making use of the water cooler facility this camera has. Instead of having to settle for -10 or -15 over summer, it would seem possible to stay with -20 or go even lower.

So I am wondering what others have found about the feasibility and practicality of water cooling systems. What is availabe commercially and what have the DIY afficianados among us cobbled together.

Peter
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Old 07-11-2011, 08:09 AM
cfranks (Charles)
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I use a water cooler for my QSI 540wsg camera and find it helps a bit , giving about another 10 degrees of coolth. I made a portable supply unit, built into a 12 litre (I think) Esky. An immersed 12v pump together with an immersed Aquarium cooler to give additional cooling. I've a feeling that the immersed pump puts just enough heat into the water to counteract the aquarium cooler so the design probably needs looking at!

Charles
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Old 07-11-2011, 08:35 AM
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I use water cooling on my ST10 all the time in the warmer months. It allows me to use -25deg all year round.
I have a plastic drum of about 30l that was originally a water drum for a drip irrigation system. It was reasonably cheap from mitre10.
In it is a submersible aquarium pump. A 200l/hr cheap pump is plenty. It is connected with ~10mm clear plastic tubing. I drape the tubing from the camera over the top of my guide scope to stop it dragging. The return water just goes back into the drum held with a bulldog clip.
The pump will only raise about 1m of pressure. To start it up I connect it up and turn it on. I have to lift the drum up to just about level with the camera and the water flows through the camera. Once it is flowing I can have the drum on the ground. The other option is to put the camera level with the pump until it is flowing.
I never spill any water and it very simple to use.
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Old 07-11-2011, 01:08 PM
Poita (Peter)
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I have utilised PC water cooling kits in the past to cool cameras, they are relatively inexpensive and readily available. I am not familiar with the ATIK in particular though.
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Old 07-11-2011, 05:35 PM
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DavidTrap (David)
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Have a read of this thread about cooling - specifically from post #36 onwards.

Chilling your water to achieve a lower overall temp is not a good idea.

DT

Last edited by DavidTrap; 07-11-2011 at 05:36 PM. Reason: Clarity
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Old 07-11-2011, 09:36 PM
cfranks (Charles)
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Quote:
Originally Posted by DavidTrap View Post

Chilling your water to achieve a lower overall temp is not a good idea.

DT
Do you have any information about this? I didn't find anything in your quoted thread. My water is only cooled to a few degres below ambient so I'm not concerned.

Charles
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Old 07-11-2011, 09:48 PM
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Quote:
Originally Posted by DavidTrap View Post
Have a read of this thread about cooling - specifically from post #36 onwards.

Chilling your water to achieve a lower overall temp is not a good idea.

DT
Hi David, yes, I read it. I understand that the previous owner of my ATIK did use chilled water in it once and screwed up the temperature sensor sufficiently badly to warrant sending it back to factory. It's anecdotal I know, but it does seem to support the point others in that thread were making about chilled water.
I was hoping to elicit some interesting ways that people have gone about circulating water through their cameras, or a pointer to some commercial products that seem to do the job well enough.
Peter
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Old 07-11-2011, 10:38 PM
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I bought a small pump and controller off eBay. I have a 25 litre container and pipes to carry the water to the block that screws onto the back of the QSI.

Turn off the fans on the camera and turn on the pump. Mine only wants a very slow flow of water (2 gallons per hour???), but other than creating vibration, I can't see a problem with faster flow.

Charles - if your cooling water is below the dew point, the back of the camera could be cooled below the dew point causing condensation to form - water and electronics don't mix. There are posts on page three of the thread that talk about corrosion forming on the PCBs if wet.

DT
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Old 07-11-2011, 10:38 PM
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I do cool the water in my container a bit in mid summer by adding some ice bricks. This realy only brings the water down to ambient as it has heated up during the day in the observatory. The observatory cools quicker than the water at night so it needs a little help. New tap water would have the same effect but the tap is over 100m from the observatory and tank water is not to be wasted.
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Old 07-11-2011, 10:56 PM
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Quote:
Originally Posted by DavidTrap View Post

Turn off the fans on the camera and turn on the pump.
I'll bite: why turn off the fan? I would have thought the stage 1 cooling still needs that to take the heat off the back of the peltier.
Peter
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Old 08-11-2011, 01:02 AM
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When water cooling a camera, the fan just acts like a heater. Turn it off.

You want to use room temperature water and as large a reservoir of it as you can. Don't chill the water (at least not below the dew point).

You also want to use a pump that preferably does not cool itself using the very water it is pumping or at least one that puts as little heat into the water as possible.
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Old 08-11-2011, 01:20 AM
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Hey Peter,
I have no experience with water cooling CCD's.
I have however, cooled my CPU, NB, SB and (for a short while) my graphics card by water cooling, using a small radiator,reservoir( non cooled), fans and a pump.
It was a success and as you can appreciate the CPU pumps out a bit of heat ( as does the NB and GPU).
So I was just thinking you might be able to forgo the ice in the reservoir and just go the radiator type setup.....
These are only suggestions as I have not tried them myself......but I would if I would get into that side of things......
( BTW I do have spare radiators, copper blocks, pumps etc for sale .... oops sorry wrong forum...... )
Bartman
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Old 08-11-2011, 01:25 AM
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When water cooling a camera, the fan just acts like a heater. Turn it off. On the other hand, if you want to make sure the camera stays above the dew point, leaving on the fan is a good idea.

You want to use room temperature water and as large a reservoir of it as you can. Don't chill the water (at least not below the dew point).

You also want to use a pump that preferably does not cool itself using the very water it is pumping or at least one that puts as little heat into the water as possible.

Last edited by frolinmod; 08-11-2011 at 01:42 AM.
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Old 22-11-2011, 03:43 AM
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Quote:
Originally Posted by frolinmod View Post
When water cooling a camera, the fan just acts like a heater. Turn it off. On the other hand, if you want to make sure the camera stays above the dew point, leaving on the fan is a good idea.

You want to use room temperature water and as large a reservoir of it as you can. Don't chill the water (at least not below the dew point).

You also want to use a pump that preferably does not cool itself using the very water it is pumping or at least one that puts as little heat into the water as possible.
In case it may be of interest to someone out there, I will quote the gospel according to ATIK received this morning:

" ... We don't sell water cooling systems ourselves, but as you say, any low power aquarium pump will do the job. You don't need high flow, just a regular flow. You don't need to disable anything, just turn on your camera as usual, and turn on the pump. You will then be able to get lower temperatures than you would with air alone.
Just a warning: Don't cool the water! Use it at ambient temperature."

Peter
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Old 22-11-2011, 05:18 AM
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Yup, low flow is usually required for a camera so as to not burst any seals. It's not like computer cooling where a high flow pump with a high head pressure is required. But just like computer cooling, you do want to be concerned about going below the dew point and having dew form inside your camera on your camera electronics. Running the fan will keep the temperature from going below ambient hence also above the dew point. If you want to go below ambient (but still above the dew point!), then you want to turn the fan off. Only do that if you know for certain you will not go below the dew point, such as when the humidity is very low and the dew point is therefore far below ambient. A large reservoir combined with the low flow will ensure that the water doesn't get a chance to heat up much. It's not like a computer cooling reservoir where you might have limited space inside the case and where the reservoir is really only there to make priming the pump easier. When cooling a camera you can use a five gallon bucket or a even 40 gallon drum if you like!
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Old 23-11-2011, 07:24 AM
Star Catcher (Ted Dobosz)
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Hi

I have been down this track for my old ST7E, where in summer I was looking for that extra bit of cooling, since every 5 or 6 drop in temp resulted in halving of noise.

Since my unit did not have the water circulating feature, I purchased a fairly hefty peltier, made up an aluminium chamber i.e. cut up six aluminum panels and used silicon sealant to create a water tight cube.

Naturally before I finished the cube I drilled and screwed in some water nipples into the cube, attached the peltier to one face ensuring only corners had a touch of epoxy and the main central area had a nice coating of thermal silicon grease. I also attached some heat sinks to the cube.

I created a jack port for power entry to the peltier on the side of the cube. The nipples were then connected to PVC tubes that led to a few metres of coild copper tubing which sat in a lidded barrel type bucket. The tubing was connected to an aquarium pump.

The peltier was attached to the outer casing of the ST7 with nylon ties, which itself is a heat sink for the camera. I would dab a small amount of thermal grease on the peltier face.

The end result was typically 6 degrees C drop. I never used ice in the system and the water would slowly warm. The more water in the barrel the better. I had to leave some power headroom in the system as the colling efficiency dropped.

Hope this info helps.
Ted
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Old 29-11-2011, 06:56 AM
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Why are people so desperate to cool their cameras as cold as possible? Have you actually compared an image of a camera cooled to -30 and cooled to -10? There is VERY LITTLE difference in the amount of noise reduction. If you are trying to detect extremely faint Sn or Asteroids at very low SNR then maybe it's worth the effort. Are you trying to detect really faint galaxies or stars? In the end seeing is going to imapact all of this more than CCD Temperature.
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Old 29-11-2011, 07:46 PM
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For the very small gains water cooling is PITA. More stuff hanging off your rig to trip over, more to setup, geater chance of causing real damage to your camera etc etc etc. If you are looking for pumps SBIG make one which can be purchased from OPT or similar (I have on here that never gets used). They are expensive and are submerged in the coolant which as stated slowly warms up over time negating the extra cooling effect unless you are going to heave a great tank full around with you. My 2c worth......dont bother just take good darks.


Mark
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Old 30-11-2011, 12:57 AM
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You'd need one with a head height of about a meter and a half peter which should be something like this, but check with a professional. These are inline or submersible but definitely not cheap and it's probably more trouble than it's worth.
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Old 30-11-2011, 04:39 AM
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pmrid (Peter)
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Thanks everyone. Good input. One of the things that has been giving me pause is the extra weight of the hoses and water hanging off the OTA plus the inherent risks of snagging a hose in the middle of the night and releasing water into an area already thick with cables and connections.
So perhaps I would be safer, and not very much worse off, just sticking to -15 which I can achieve even in mid-summer. Another possibility I'm going to look at is those little bolt-on fans that SX are now selling as an add-on for the SXVR_H18 and similar. In a camera that uses the body as a heat sink (like the ST7 and others) then this may just give me a little extra at no real cost.
Peter
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