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Telegizmo 365 Scope Cover Fails Rainfall

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#1 Gregory2012



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Posted 12 April 2021 - 11:55 AM



I own a slightly over sized Telegizmos scope cover, the 365 day a year cover for a 9.25in scope, fork arms, pier and wedge. It's basically new with out rips or holes. I had it covering the pier and Celestron HD Wedge during a recent rain fall. After significant rain for a few days, I found moisture and wetness all over the pier and wedge. Almost as if there wasn't a cover to begin with.


Is this normal? I expected the setup to be mostly if not completely dry. The cover was draped over every thing down to the bottom of the pier, but was not tied off any where. Fortunately, I had brought the scope in, so it didn't get wet.


Thank you.

Gregory Gig Harbor, WA.

Edited by Gregory2012, 12 April 2021 - 11:58 AM.

#2 zakry3323


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Posted 12 April 2021 - 12:04 PM

Telegizmos are guaranteed to provide protection through any weather conditions, 365 days a year, as the name implies. If yours has a detectable leak, it's defective and should be replaced. I noticed during long stretches of humidity (ok, all summer long), that water vapor condenses underneath the scope cover. To prevent this, it's become necessary for me to run a small 12v fan and an EVA-Dry wireless mini dehumidifier.  

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#3 pyrasanth



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Posted 12 April 2021 - 12:04 PM

This is not normal even though you might expect a bit of condensation. I had the same issue a few years back & I contacted Bob Pitney who kindly replaced the cover for me. It is possible you have a faulty cover however explore the possible issue of condensation as well. I have three of these covers in use and I don't get issues like you are experiencing.

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#4 Cfreerksen



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Posted 12 April 2021 - 12:05 PM

You are no doubt having a dew problem. When the day starts to warm up the metal and glass under the cover is still cold and dew will form under the cover. I would suggest a heat source under the cover. I use this under my cover and have had good results. https://www.amazon.c...e?ie=UTF8&psc=1


But then I am in a pretty dry climate. Others have used low wattage light bulbs. 



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#5 c2m2t


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Posted 12 April 2021 - 12:31 PM

Hi Greg!

One quick suggestion to see if the cover is defective. I store scope & mount combinations outside all summer long. I always have some redundancy in my covers. In my case, I place a large, heavy duty (Contractors) garbage bag over the scope and mount prior to adding a second cover made from a basic tarp which I seam and seal to create a large bag. If the outside of a garbage bag placed under your 365 cover is again significantly wet after a good rain, then it is likely that the 365 cover has a defect. 


I suspect your location suffers from high humidity and if that is the case, some form of dehumidifier/heater may be your only solution. If your general local humidity is high, heat may not be enough...you may have to introduce some kind of air flow. You might be able to accomplish this with a solar powered fan...or a better solution may be a low voltage computer style cooling fan attached to a lightweight flexible duct to move air out from under the cover. 


Lets us know how you fair with the garbage bag test. It would be great if it is simply a defective 365 cover. 


Another thought crossed my mind...when you are doing further testing of the cover, see if you can reduce the opening at the the open, lower end of the 365 cover...some of them come with string/elastic to cinch off the the opening...clothes pins or paper clamps can do the job as well. Reducing the air flow that can get up into your cover during these rain events, may be just enough to mitigate humidity from getting built up underneath the cover.


Cheers, Chris.

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#6 mich_al


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Posted 12 April 2021 - 01:34 PM

Had a similar issue with my 365 that was about 8 years old.  I called Telegizmo to see if my cover had reached its lifetime.  They told me to seal the seams with a camping tent product.  It's been good for several years now.  The key to anything covered outdoors that is susceptible to moisture is to MONITOR the humidity there, just placing some rando desiccant under there and hoping it all keeps dry is gonna guarantee problems.

Edited by mich_al, 12 April 2021 - 07:38 PM.

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#7 WadeH237


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Posted 12 April 2021 - 03:36 PM

It's 100% condensation.  In order for the entire rig to be wet, you'd need a huge hole and it would be obvious.


When I had my rig under a TG365 cover in the Seattle area, I always kept two Goldenrod heaters under the cover.  Goldenrod heaters were designed for use in gun safes to prevent condensation, and they work great under scope covers as well.


Another, much less obvious, head scratcher is that on a couple of occasions, I uncovered my rig to find the scope filled with water.  The rig itself was dry, but there was enough water in the scope that I needed to dump it out.  When it happened on my EdgeHD 8, I was able to dump the water out through the vents.  When it happened with my C14 (without vents), I needed to remove the corrector plate to dump out the water.


It took me a while to figure out what was happening.  Since it's such a rare occurrence, I'm still only 95% sure of the root cause.  Anyway, in both cases, it happened after a fairly long stretch of freezing weather (and only twice in at least 5 years of having the rig out under cover full time).  I think that the problem is that the TG365 cover was draped over, and in direct contact with, the scope.  I think that this created a conduction mechanism where, even with the heaters, the heat inside the scope was able to escape through the cover.  I think that this super-cooled the inside of the telescope and every bit of moisture under the cover condensed inside.  To prevent the problem, I always fold a towel into many layers and drape that over the scope before putting on the cover.  Since doing that, the problem has not recurred.  Again though, since it's so rare, it's not 100% conclusive, although it's been many years (and winters) since it happened last.


In the last year, I've changed the way that I store my gear.  I used to leave the rig out under cover and ready to go at any time.  Because I do travel for astrophotography, I made some changes to my cabling and mounted much of the gear on top of the OTA, such that there are only two connections  (one power and one USB) that need to be plugged or unplugged to mount or unmount the scope.  And since all of the other gear is mounted on top of the scope, I add or remove it in one piece.  It takes about 2 minutes to do the whole thing.  Since it's so easy now, I only leave the OTA, camera, etc. on the mount when I know that I have clear nights in the immediate future.  Otherwise, I just unmount the OTA and bring it all in, again in one piece.

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