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Old 11-24-18, 02:35 PM   #1
Geo NR Gee
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Default Prompt guidance requested in a new Drainback system

Thank you for opening this post. Short version is I have a lot of evacuated tubes sitting on the side of my house collecting dust. I am getting help today to install the racking for the tubes and maybe the tubes.

For the last few weeks, I have been looking for the proper way to use them in a drainback system with water (no antifreeze). These are the Thermomax HP200 tubes and are about 7' per section. They have snapdiscs in them to prevent overheating. Mine are the 195* cut off ones I believe.

Experimenting with the different drain slopes yesterday was to fill the manifold on one end with water and measure how much came out at a specific angle.

It seems like the acceptable result was 1 tablespoon of water left over in a 7' section at 9:12 pitch or 4.4* angle, slope is 7.7% according to the slope calculator. With 3-7' sections, is that a problem for freezing?

I have done weeks of research and frankly it's just going to sit another year unless I just get it done. Hoping someone can save the day before we make a big mistake.

I watched videos by Dr. Ben and he shows many viable ways, but I only see he recommends 1" in 20' or 1/4* slope, however I think that is for a unobstructed manifold. The Thermomax manifolds and other evacuated tube collectors have the heat riser pipe going directly into the liquid stream of the manifold. I tried that with the Thermomax manifold and it is way to much water left inside of the manifold. The 4.4* angle slope is much better if a tablespoon of water over the entire 7' length is acceptable.

Geo

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Old 11-24-18, 02:40 PM   #2
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This is the cutaway of the Thermomax HP200 manifold
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Old 11-26-18, 01:35 AM   #3
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The racking and frames were installed today. The evacuated tubes will be installed in the next few days. We will test the drainback after all manifolds are connected. Hopefully the drainback slope will be sufficient to prevent freeze problems.

Maybe Monday I will receive information from the manufacturer if the system will work that way.
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Old 12-04-18, 01:29 AM   #4
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The bottom of several evacuated tubes are cracking and popping out. I lost a total of 6 today while they were seated in the collector manifold and rack. Any ideas?

One of the times one broke, I was standing about 15' away and when it cracked my right ear started hurting. The noise was not loud at all, but it must have been a strong frequency. That was strange.

Back to the cracking and breakage, I am thinking that the rubber plugs on the bottom of the tubes are holding moisture. It was in the low 30's F last night. Plus I washed the tubes with soap and water. It was past dark too. I thought I dried them well enough, but maybe not although I am not thoroughly convinced.

In the attached pictures you can see the rubber plug and the sealant that was applied to the rubber plugs. Not sure what kind of sealant it was.

The plan....
1. clean the plugs in the dishwasher. Done......very clean after running them thru the dishwasher.......before she got home..
2. find out what the sealant is and reseal them.









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Old 12-04-18, 08:19 AM   #5
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Thanks for posting pictures and info on this. I have never seen one of these systems up close very interesting. I always wondered how fragile they were.
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Old 12-05-18, 04:13 PM   #6
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They seem to be pretty stout if you bang them up against anything, which I have done a lot. The glass is pretty thin at the bottoms where the rubber plug is. Yesterday I lost two more and today they are all good.

Next is to figure out how to get the transfer fluid to and from the house. The evacuated tube supply line is 10' high off the ground and I have an area that I need to go underground to get to the house. The whole goal is to get this to be a drainback system, but that is becoming more of a challenge.
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Old 12-26-18, 08:20 AM   #7
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I've put in lots of Thermomax and Viessmann (which is the same tube) and never had this issue with them. Thermomax is defunct now so you must have got them from a reseller. No moisture on them will cause this especially just around freezing but what will is having the lower clamp too tight so the glass can't expand and contract. I can't see another reason for it breaking unless there is no vacuum in there at all and at that time you will see that there is no "getter" ring at the bottom anymore, indicating a vacuum breech.
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Old 12-26-18, 12:15 PM   #8
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Even after a few weeks, I lost three more. The vacuum was still present in the tubes since the getter ring was present, but after they broke, the getter ring blew. So far this week, non have broke. They only pop out at the bottom. I noticed the last three started with a very faint crack then in a day or two, the break the rest of the way.

The clamp at the bottom of the tubes are a rubber like material and are not adjustable like a radiator style clamp.

The tubes were made in late 2013 according to the stamp on the fins inside the tubes, so yes, they are a few years old and I got them from a business that went bankrupt.

Did Kingspan Solar buy them out? They are the ones that I was talking to about 6 months ago to order some elbows. Now the US phone number has a recording to refer to the parent company.
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Old 12-26-18, 12:26 PM   #9
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Kingspan is the parent company in Ireland but I am pretty sure they are gone from North America. It used to be headed up by a guy named Partick Spearing but no one can get parts unless you buy the Viessmann tubes which are a bit more expensive.

There is still some part of the tube that has to be able to move a bit or cracking will occur.
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Old 12-26-18, 12:57 PM   #10
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Thanks Randen and Mike. I spoke with Kelly at Viessmann a few minutes ago and they are only selling the replacement tubes for existing systems and no longer sell the equipment. He said they are hooking me up with a dealer in my area.

Below is what the clamps look like. I made sure the copper receiver at the manifold for the evacuated tube collector was clean and smooth before I placed each tube in its spot and then used the clip to fasten them in.

If they are breaking when they expand, maybe I should work the rubber clamps closer together so that when they do expand, they are not under pressure in the wrong direction? Or would I put some kind of grease on the clamps to allow it to slide a bit? Something that would hold up in the weather and sun?

It is curious why they didn't break when they were originally installed and sitting stagnant in place for a year or more before they were relocated.

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