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Dew, and leaving mounts outside

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#1 hottr6

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Posted 22 September 2014 - 11:39 AM

I had this brilliant idea of leaving the mount outside permanently, thus maximizing my observing time by minimizing setup times.  How often is that idea conjured?

 

Before committing my G11 to the great outdoors, I wanted to conduct an experiment to find the best solution to mitigating dew formation under a cover, in this case, a small 365-cover by Telegizmos.

 

I figured that I would put a bucket of DampRid to capture any vapor.  During days of desert dryness, the system worked great.

 

Dew2.jpg

 

A few days ago, we were sideswiped by Hurricane Odile, receiving 30% of our annual rainfall in 24 hours, so I decided to check on my little outdoor experiment.  Uh-oh, horrors upon horrors!

 

Dew1.JPG

 

This experiment did not work well.  The DampRid bucket had over a cup of water and the mount was pretty saturated.  The underside of the 365 cover was dripping water.

 

How do people keep their rigs dry under these "telescope covers"?



#2 mich_al

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Posted 22 September 2014 - 12:31 PM


How do people keep their rigs dry under these "telescope covers"?

I monitor the under cover humidity remotely (Oregon Scientific BAR388HGA and THGR122Nx). If you're gonna cover it then you have to actively monitor what's going on. I also have a good desiccant under there.  If it's gonna be wet I turn on a protected 100w light bulb till the humidity drops.  Allow air to flow thru the 365 cover. I don't cinch the bottom unless its raining/windy.  Remove the cover to air out when appropriate.  I never have yet but for a hurricane/extreme rain I might use a waterproof bag underneath while the storm is raging.  Others have reported leaks under extreme conditions in 3+ years I've never had a leak.



#3 dawziecat

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Posted 22 September 2014 - 12:39 PM

Many people have had success with waterproof covers, like the Telegizmos.

 

I did not! 

 

My G11 might have well been totally submerged as left under that cover . . . both in Nova Scotia and in Florida.

 

The suggestions to to use desiccants, a light bulb or dri-rods were way off the mark. They could not have kept up with what was condensing under there.

It all depends on local conditions and what kind of surface your tripod is sitting on. If it's grass . . . forget a waterproof cover!

 

I did find the TG useful in winter to keep snow off. In other seasons, I preferred a simple garbage bag which I removed during daylight hours if rain was not expected.

 

You seem to be dealing with a graveled surface? Maybe a TG will work well for you, especially with a dri-rod.



#4 end

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Posted 22 September 2014 - 02:19 PM

I feel like I post a response on this topic several times a year, but I'll just chime in with my usual: I have a Telegizmos 365 which I use to cover a C11 and CGE-PRO in my back yard. I live just south of Houston, TX and humidity levels are very high here. In the morning relative humidity is usually between 80 and 90% and on occasion approaches 100%. When I used the cover alone I would find that all the instrumentation underneath it would become covered in dew every morning. I later added a 60W light bulb and this entirely fixed the problem. Subsequently I reduced the wattage to 40W and this still results in near zero condensation. The whole system sits above grass which gets quite wet, but the light bulb seems to keep the ambient temperature inside just warm enough to prevent condensation. The only place I ever still see condensation are at the very top of the scope where the bag is in direct contact with the scope/mount, but this is pretty minor and doesn't concern me. I'm sure that if I wanted to eliminate this residual water problem (pun intended) that it could be fixed by devising a small spacer to allow air flow between the bag and the scope & mount.

 

I've also left the mount out during torrential rain have never had any problems with leakage. If you are using a larger mount like I am I would be somewhat concerned about leaving it set up if you expect high winds because the large cover acts a bit like a sail and in extreme conditions could potential lead to the system being overturned.


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#5 lambermo

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Posted 23 September 2014 - 01:44 PM

I tried a 60W bulb under a 365 telegizmos . Not enough for my humidity by far. Tried 100W. Still not enough. Now I cover it up, humidity-tight, and add dehumidifier packages and a humidity measurement device with remote rf display to see if and when the packages need an oven or microwave refreshing. I do this 4 years now. Humidity-tight here meant I had to add a sturdy plastic cover underneath the 365 telegizmos as its seams are not water (let alone vapor) proof. It's an excellent outside cover nonetheless. I'm happy with it.

20101009-TelescopeCover.jpg


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#6 dawziecat

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Posted 23 September 2014 - 02:04 PM

I think there are a couple of situations, each different.

 

1/ Using a waterproof cover to keep gear, already dry, dry.

2/ Covering gear already wet from a session.

 

In situation 1, a waterproof cover, with dri-rod/light bulb may work very well.

 

Situation 2 is entirely different IMO!  Gear already wet from dew can not reasonably be covered with a waterproof membrane that is going to trap any moisture evaporated by heat.

For me, that was every session!

 

 

I also found the TG very heavy. It was a chore to cover the gear with it. The bigger your gear, the more this will be an issue. It was forever snagging a finder or guider or getting hung up on the counterweight bar. In the end, I decided to bring the optics and electronics inside and just cover the mount.

 

I think the important thing to take from the thread is that moisture under a waterproof cover is very real and it must be managed. Color me naive but I bought a cover thinking the problem was done with. That certainly is not so . . . not in humid environments anyway.



#7 jzeiders

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Posted 23 September 2014 - 02:43 PM

Agree with many points already mentioned. Moisture over time will damage mounts, telescopes, and electronics through accelerated corrosion and possible fungus.

 

Having a heater and or dehydrator to reduce or evaporate condensation is a good idea. Don't forget that water vapor is a gas and will get everywhere you don't want it. Most if not all astronomical gear is not weather sealed and will suffer from long term exposure, what you see on the outside is also likely on the inside to some degree. If you live in a salt environment leaving your gear outside could be a quick way to shorten its useful life.

 

A related point is to not close up or put dewed up equipment into a sealed case when it is still wet. Leave the covers off and a scope, mount, controller, etc. out of the case until it warms and dries thoroughly when breaking down after a cold and or wet evening. 

 

Jack



#8 neptun2

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Posted 23 September 2014 - 05:01 PM

I personally have never left my equipment outside for more than 3 sequential nights (at our big summer star party). During that time i usually used cloth to cover the scope after the session if weather is good and without chance of rain or nylon if there is chance of rain during the day. I also took the cameras, laptop and other electronics in my car to because they are much more sensitive to moisture. In every other case i took everything home after observation and leave it in warm dry room so that it can acclimate properly and the moisture to be removed from it. I personally would not keep my equipment permanently outside. 


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#9 hottr6

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Posted 24 September 2014 - 05:11 PM

I think the important thing to take from the thread is that moisture under a waterproof cover is very real and it must be managed. Color me naive but I bought a cover thinking the problem was done with. That certainly is not so . . . not in humid environments anyway.

Not in dry environments, either.

 

In the experiment I detailed above, I had been visually checking under the TG365 cover.  During dry desert days, there were no problems.  Humidity during those days was less than 20%.  Along comes a storm and WHAM!  Humidity shoots to 96%.  After the rain subsided, the mount was wet, despite the DampRid.  If I closed up the cover when the air was dry, where did this moisture come from?

 

As noted above, water vapor is a gas.  During the storm, the air pressure rose and dropped.  Because the TG365 cover is not sealed to air flow, the water vapor gas mixed with the dry air under the cover.  As the temperature falls to the dew point, the vapor condenses into a liquid.

 

I do believe that the TG365 is water proof, but we are unable to make a tight seal around the base of the cover, thus permitting entry of humid air.  Here is a picture of my setup (DampRid bucket is underneath the cover).

IMG_5384.jpg

 

Thanks to all that replied.  The solution to dew forming under covers is not straightforward as some may believe.  I still have some things to try and will report back to y'all.



#10 A. Viegas

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Posted 24 September 2014 - 08:30 PM

Well there are definitely trade offs in leaving equipment outside and ready to go...  I have left my cpc11 outside now for almost 2 yrs under two telegismos, a solar huge dob cover which covers down to almost tripod feet and a 365 large cover which covers down to just below the wedge.  It's been through hurricane sandy, 4ft of winter snow and blistering hot humid summer days. Often I leave it 2 or more weeks before I get to use it.  Does it have dew? Dunno don't pay attention to it.  When I use it I uncover and then usually cclose up until next week.  How many more years will I get out of it, dunno... But heck this stuff is supposed to get used.. My time to use it is limited. 2 hrs to set up would kill a large part of any aavailable time.   So heck I guess it matters to try and perfect the dew issue.., but really it's about using the equipment.  It's going to eventually break down, so my view is get the most use I can and not worry too much about these types of details.  I am sure even people with observatories worry about dew and pests but frankly it's about getting the most out of your equipment while you can.  A little dew here and there is small price to pay for not hhauling the heavy equipment out and wasting time on setup. It's not perfect but its a trade off I am willing to endure.

 

Al


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#11 Mike G.

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Posted 26 September 2014 - 02:50 AM

Hi All, just another viewpoint.

 

Living in NorthEast Ohio we get everything from snow to ice storms to 100F and 85% RH days in the summer with rain sometimes an inch in 2 hours and gusts to 60 mph. Personally, I am quite fond of my 8" newt and pier-mounted CG5-ASGT and don't want anything nasty happening to them. I also have to deal with setup times that frequently are longer than the time of available cloudless skies so I am always looking to shorten the setup time.  to that effect, I have my newt, rings and dovetail kept inside assembled and usually leave the mount on the pier outside under a $11 Wal-mart grill cover.  this seems to keep things pretty dry; I don't cinch the bottom of the grill cover very tight so air moves around inside pretty aggressively. the pier is concreted into the ground and in the center of an elevated wood deck with limestone under all the wood. so pretty dry directly under the mount most of the time. The grill cover is a great low cost option to the TG I think.

 

still, if I know I am not going to be using the scope for a couple weeks (I travel frequently for 2-3 weeks at a time), I remove the mount and bring it inside.  with the CG5 a single bolt in the center is all that holds it to the top plate but I don't like losing my polar alignment when I do that! besides the weather, we have brown recluse spiders and hornets that love to find dark warm places to build nests. so I have a little bit of paranoia about leaving the mount outside permanently.  the scope has never seen the sun come up but the mount stays out frequently, sometimes for 2 or 3 months at a time with no detectable effects.

 

even so, I recently bought a used CG5 for the sole purpose of having spare electronics that I can go through and thoroughly weatherproof.  when that project is done, I will feel a lot better about leaving the mount out for extended periods.

 

clear skies!



#12 Mark9473

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Posted 26 September 2014 - 06:30 AM

hottr6, on 22 Sept 2014 - 6:39 PM, said:

 

A few days ago, we were sideswiped by Hurricane Odile, receiving 30% of our annual rainfall in 24 hours, so I decided to check on my little outdoor experiment.  Uh-oh, horrors upon horrors!

 

This experiment did not work well.  The DampRid bucket had over a cup of water and the mount was pretty saturated.  The underside of the 365 cover was dripping water.

 

 

Do you think there's anything in that M2, apart from perhaps the screws, that has a problem with getting wet?

It's not like there's electronics in there.

Not trying to challenge you, I'm just curious as I've been contemplating the same for my DM6.



#13 dawziecat

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Posted 26 September 2014 - 11:03 AM

I was very pleased to see Al's post as his thinking is precisely the same as my own. So many people seem not to feel this way.

Use the gear!!!! Do whatever you must and can afford to protect it but whatever must be done to maximize its use should be done.

My goal has always been to get as many photons down to the sensor as possible. If the aluminum  gets wet, even frequently, so be it! There is nothing ferrous in most of these mounts. They do not "rust."

 

Many people do not feel this way though. They seem to strongly desire that their stuff be maintained in pristine "just out of the box" condition and appearance.

 

No doubt many would say what I did was tantamount to "abusing" the gear.

 

There were MANY times when my G-11 could not possibly have been wetter had it been submerged in a tank of water. Didn't seem to hurt it.

I DID come to bring the electronic module and optics in if I was not going to be able to image for more than a day or so. The mount stayed out, always.

 

I did try to minimze its "wet time" by uncovering it and letting it air dry as much as possible. AFAICT, this, in no way, affected the mount's performance.

It DID affect its appearance in that the anodized finish "weathered" to a deep "eggplant" colour in the sun. This was barely discernible with the eye, but, for some reason, was quite apparent in photographs. I am sure it did not help at re-sale time.

 

I think it more important to get the most use out of the stuff than worry too much about non-ferrous metal parts getting wet.

Optics and electronics are a different matter. Do what you must to protect them, including bringing them inside if no "breathable" shelter is possible for them.


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#14 jzeiders

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Posted 26 September 2014 - 03:01 PM

Apparently some missed the thread from the guy with the rusted bearings in his mount, he had to send it in to have them replaced. Ball, roller and needle bearings are usually steel. If your mount does not have any such bearings, it likely does not matter much.

 

He is not the first nor will he be the last.

 

Jack



#15 kalasinman

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Posted 10 October 2014 - 09:30 AM

I'm sure I've missed something here. Don't pier mounts, weather and obsys fit in the same discussion?--Jack



#16 Nitpick

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Posted 14 October 2014 - 11:49 AM

I leave my two main telescopes, a Celestron 11" EdgeHD and 130MM Stellarvue, outside 24x7x364 -- each on its own mount (a CGEM and AVX respectfully).  I've done this for over a year so far and don't notice any negative effects other than some of the cell screws on the Celestron have rusted a bit.  But the mirror is perfectly clean and there is no evidence of moisture inside either tube.

 

I live in a valley and every night here in Southern Indiana I get extreme dew formation.  When uncovered, my scopes and mounts will be DRIPPING WET after just a couple hours.  Not just sometimes, but EVERY NIGHT.

 

I have to use dew heaters around the OTAs, on the eyepieces, around the guidescopes, in the dew shields, etc.  They are absolutely mandatory for any session.

 

I use tele gizmos covers on both scopes and do not notice any dewing or condensation so long as the covers are on.  I generally leave the base of the covers "open" so that air isn't trapped beneath them.  If I have to cover the scopes when they are wet (i.e. before turning in for the night), I try and make a point to un-cover them in the morning so that they can dry off before I re-cover them.

 

It is not practical for me to haul out the telescopes from inside every time I want to use them at night.  In particular, the EdgeHD would have to be recollimated and both scopes would have to be reconnected to the dew heating system.  I don't want to lose that time from what are usually limited use opportunities (due to sky conditions).

 

I have thought about adding some kind of supplemental heat, like a light bulb, under the covers when not in use but so far have not gotten around to hooking it up.  Too lazy and, again, I don't see evidence of moisture so long as the scopes are covered and not "put up wet."


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#17 torsinadoc

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Posted 14 October 2014 - 12:17 PM

I leave my two main telescopes, a Celestron 11" EdgeHD and 130MM Stellarvue, outside 24x7x364 -- each on its own mount (a CGEM and AVX respectfully).  I've done this for over a year so far and don't notice any negative effects other than some of the cell screws on the Celestron have rusted a bit.  But the mirror is perfectly clean and there is no evidence of moisture inside either tube.

 

I live in a valley and every night here in Southern Indiana I get extreme dew formation.  When uncovered, my scopes and mounts will be DRIPPING WET after just a couple hours.  Not just sometimes, but EVERY NIGHT.

 

I have to use dew heaters around the OTAs, on the eyepieces, around the guidescopes, in the dew shields, etc.  They are absolutely mandatory for any session.

 

I use tele gizmos covers on both scopes and do not notice any dewing or condensation so long as the covers are on.  I generally leave the base of the covers "open" so that air isn't trapped beneath them.  If I have to cover the scopes when they are wet (i.e. before turning in for the night), I try and make a point to un-cover them in the morning so that they can dry off before I re-cover them.

 

It is not practical for me to haul out the telescopes from inside every time I want to use them at night.  In particular, the EdgeHD would have to be recollimated and both scopes would have to be reconnected to the dew heating system.  I don't want to lose that time from what are usually limited use opportunities (due to sky conditions).

 

I have thought about adding some kind of supplemental heat, like a light bulb, under the covers when not in use but so far have not gotten around to hooking it up.  Too lazy and, again, I don't see evidence of moisture so long as the scopes are covered and not "put up wet."

 

I leave my AVX covered with Telegizmo 350 outside (snow, huge rain storms, etc). I wrap the mount head with a towel, cover with a trashbag then TG Cover. Never had a drop on the mount.  I usually take my scope inside unless I am certain the weather is going to be good that day and I am imaging multiple nights.  I get a little concerned with the wind but (mount only) has survived heavy wind (30-50 gusts).  I had a small leak once with my TG cover and they replaced it free of charge immediately.  I live in the south and the mount gets covered with water during summer nights because of dew. I make sure it is dry priior to replacing the cover.



#18 Stephen Kennedy

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Posted 14 October 2014 - 12:22 PM

This is my telescope:

 

http://i.imgur.com/HKRxYGu.jpg

 

The OTA has a mass of 22 kg and the mount a mass of 150 kg.  Obviously, moving it outside and inside again every night would not be possible.  I looked at the various covers on the market for telescopes that are left outside permanently and was not satisfied with any of them.  My wife made a cover out of water-proof canvas that fits over the entire telescope all the way to the concrete base.

 

I never get any moisture on my mount or OTA and my setup shows no ill effects from being outside for several years now.  It could be that my wife made a superior cover that renders the telescope impervious to the elements or it could be because I live in California where the humidity is low and dew is rarely seen.  Even after it rains, if I take the cover off the mount and OTA are bone dry.

 

I was going to purchase an $8,000 Pro-Dome observatory to protect my telescope.  However, it occurred to me that spending a lot of money to build an observatory in a light polluted area did not make much sense and the telescope was just as well protected from moisture under the cover my wife made as it would be in a backyard observatory.



#19 timtrice

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Posted 14 October 2014 - 12:45 PM

On a side note you guys don't have wind tolerances? I brought mine in due to threat of 50mph winds but didn't even set back up last night due to 20mph winds forecast today...
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#20 hottr6

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Posted 14 October 2014 - 01:02 PM

 

The solution to dew forming under covers is not straightforward as some may believe.  I still have some things to try and will report back to y'all.

 

 

I have been conducting some experiments with the rig that I picture earlier in this thread.  New Mexico has received a LOT of unseasonably late rains, and this time of the year we are dealing with high humidity (90%) around dawn with subsequent dewing/frosting.

 

I placed a wireless hygrometer and thermometer under the TG365 cover to watch things.  As an aside, the temperature under the TG365 has not exceeded 90F this Autumn.  Humidity under the cover has ranged from 10% to 85%.

 

I re-arranged things differently under the cover, after noting that humidity presented a vertical profile depending on the location of the hygrometer in the bag.  Lower in the bag (near where the drawstring is cinched) the humidity is relatively lower than higher in the bag.

 

Armed with this, I moved the bucket of DampRid to near the top of the mount, and I try to make sure there is some clearance between the top of the mount and the bag.

 

Over the past 2 weeks, NO CONDENSATION!  Far from being an exhaustive and conclusive experiment, I will tentatively state that it appears that moving the bucket of DampRid 6" higher in the small TG365 bag appears to have made a substantial improvement to the condensation problem.  The experiments will continue.

 

Summary:  For people doing active condensation mitigation, locate the desiccant to the top of the mount.


Edited by hottr6, 14 October 2014 - 01:29 PM.

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#21 hottr6

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Posted 14 October 2014 - 01:20 PM

 

hottr6, on 22 Sept 2014 - 6:39 PM, said:

 

A few days ago, we were sideswiped by Hurricane Odile, receiving 30% of our annual rainfall in 24 hours, so I decided to check on my little outdoor experiment.  Uh-oh, horrors upon horrors!

 

This experiment did not work well.  The DampRid bucket had over a cup of water and the mount was pretty saturated.  The underside of the 365 cover was dripping water.

 

 

Do you think there's anything in that M2, apart from perhaps the screws, that has a problem with getting wet?

It's not like there's electronics in there.

Not trying to challenge you, I'm just curious as I've been contemplating the same for my DM6.

 

 

Well, yes, there are several reasons why it is important to keep your DM6 dry.  If water gets gets between the teflon bearing and surface and freezes, you may not be able to move the mount and observing session over.  Think of what ice crystals on the bearing surfaces could do.  Water carries with it particulates that will be deposited when the water dries.  These particulates, if deposited on bearing surfaces, will lead to less-smooth movements.  Finally, water is not a lubricant, and its presence alone on bearing surfaces will make the mount stick.  QED.



#22 hottr6

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Posted 16 October 2014 - 08:39 AM

More updates.  I replaced the DampRid bucket with one of these.  Eva-Dry units use silica desiccant instead of calcium chloride used by DampRid.  The silica dessicant can be dehydrated by simply plugging the Eva-Dry into a 110V wall socket and then re-used.  The CaCl crystals are a one-time use only.

 

I placed the Eva-Dry unit at the same location under the TG365 cover as the DampRid bucket, and over a period of 2 days, observed that the Eva-Dry reduced humidity relative to ambient by 15-30 % points better than the DampRid.  I.e., the DampRid would reduce humidity under the cover by up to 15 % points below ambient, and the Eva-Dry would reduce humidity by up to 45 % points below ambient.  At this time, I suggest that the silica dessicant is more effective than CaCl at reducing humidity under a bag cover.  I will update this hypothesis as I collect more data.

 

I have yet to see how long the Eva-Dry unit will last before it needs recharging.  Stay tuned!



#23 stellarvuelomo

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Posted 16 October 2014 - 07:33 PM

This is my telescope:

 

http://i.imgur.com/HKRxYGu.jpg

 

That is an awesome looking mount!


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#24 hottr6

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Posted 09 November 2014 - 01:22 PM

More updates.  I replaced the DampRid bucket with one of these.  Eva-Dry units use silica desiccant instead of calcium chloride used by DampRid.  The silica dessicant can be dehydrated by simply plugging the Eva-Dry into a 110V wall socket and then re-used.  The CaCl crystals are a one-time use only.

 

I placed the Eva-Dry unit at the same location under the TG365 cover as the DampRid bucket, and over a period of 2 days, observed that the Eva-Dry reduced humidity relative to ambient by 15-30 % points better than the DampRid.  I.e., the DampRid would reduce humidity under the cover by up to 15 % points below ambient, and the Eva-Dry would reduce humidity by up to 45 % points below ambient.  At this time, I suggest that the silica dessicant is more effective than CaCl at reducing humidity under a bag cover.  I will update this hypothesis as I collect more data.

 

I have yet to see how long the Eva-Dry unit will last before it needs recharging.  Stay tuned!

 

We have had some very damp weather in central NM over the past few weeks.  The colder weather prevents the ground from drying out, so most mornings we are greeted with very heavy dew or frost.

 

The Eva-Dry unit has been working well, and I have not seen any signs of condensation under the TG365.  After 3 weeks, the Eva-Dry unit declared its self at capacity, so I plugged it into a wall socket and it had dried its self out after 14 hours.  I reset the counter 'till when it again needs discharging.

 

So far, I am pleased with this experiment.  Using an Eva-Dry unit and being able to remotely monitor the humidity under the cover are important elements in this mission.  The rest of the job, due diligence, is up to me.

 

DewMgmtV2.JPG

 

The following photo shows the Eva-Dry indicator after 3 weeks, just before discharging.

 

EvaDry_needs_emptying.JPG


Edited by hottr6, 09 November 2014 - 01:27 PM.

  • GJJim and StarWolf57 like this

#25 hottr6

hottr6

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Posted 23 December 2014 - 01:55 PM

Update:  Our late Autumn has been damp with above average snowfall.  I have seen zero standing water under the TG365, and the Eva-Dry unit needs to be recharged again...... the first recharge since early November (about 6 weeks ago).

 

I am feeling confidant that this is a good working system.




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