Solar Flashing Detail Question

Constantin

Now that the Vitosol system on my roof is finally fully functional, the next question is how to finalize the installation. The tubes and their headers are happy and well-anchored, yet the rest of the system is a little less than professional at the moment.

Specifically, my installer had no experience installing a Vitosol before this project. While Viessmann calls out in their installation manual to use standard flashing details, they don't really elaborate how to best get the tubes through the roof. For now, we have a capped copper chase that they run in, along with the thermal sensor wire.

My question to the solar experts out there is how to best seal the penetration? I would like to use a high-R insulator like "good stuff" but wonder if the insulation wouldn't get a bad hair day if we have stagnation up there. I figured that if I used closed-cell polyurethane for the chase that I'd "cap it" with high-temp silicone to keep any eventual water out of the polyurethane.

Naturally, I could also silicone the whole chase... that would be pretty expensive though and I doubt the insulation value of the red stuff is high.

Also, what products have you used to wrap the external pipes before they enter the header? Viessmann would like to use a Al-covered or similar insulation, it seems, yet I have not found any specifications. Any pointers would be much appreciated...

EDIT: Now a pic is attached, showing the vent w/o the benefit of a vent cap.

ALH_4

Seal

Techlite makes a nice UV resistant jacketed insulation. I can't get their webiste to work this afternoon. I believe it's the 379 series insulation.

Are you trying to match copper flashing with the copper chase? You could stuff the chase with Armaflex HT and cap the whole thing off with Master Flash.

-Andrew

ALH_4

After seeing the photo....

Why not get a copper cap that fits that chase pipe and bore two holes in it and solder or braze the pipes into the holes in the cap? Be sure there is room for expansion movement at the bottom of the vertical pipes.

In order to get the cap on after the fact, maybe you could cut it in half after boring the holes and braze it back together in place.

BTW I'm not that impressed with 1/8" NPT air vent adapters. They generally have very small holes for the air to get through. 1/4" and up work much better IMO. Caleffi makes all sizes with service check valves, and I've been very impressed with them.

-Andrew

Larry Weingarten

It is a little...

... off topic, but that air vent will leak some day. When it does, water will run straight down the pipe into your house. I've seen just this detail cause tens of thousands of dollars damage. Either offset the vent and hope it cannot freeze, or add a drip cap (perhaps some copper sheet drilled and soldered under the vent, to drip off to the side) or some other non-caulk method of waterproofing. Best is to remove the vent entirely and run a tube down to a valve in a warm location that you can use to bleed the system (if that fits in with system design?)

Yours, Larry

Constantin

Thanks for the replies!

Andrew, many thanks for your insights and helpful links.

We currently have a top-down cap that fits over the whole assembly and which is 2" wider than the 2" pipe sticking through the roof. I think I am going to spray/fill the cavity inside the chase with "Great Stuff" unless it will decompose at stagnation temperatures.

I presume this will not be an issue and that closed-cell polyurethane foam is good for the temperature but some further review is necessary as the MSDS sheets that Dow publishes are for the unexpanded product, not the finished form.

My next step would then be to wrap the exterior of the copper pipe (both the through-roof and the top-cap) with Armaflex HT as per your suggestion. I'd paint it gray to plend into the roof and to provide UV protection. Then fill the interior of the top cap with loose fiberglass before putting it over the vent. The covers would then be screwed into the header box and sealed in place with silicone.

You correctly identified that this is not the standard-issue Viessmann vent. My installer didn't order one or lost it and I am surprised that Viessmann doesn't offer a neat through-roof solution, the way they offer a neat, orderly U-bend cover for the supply pipe at the other end of the header.

Thanks to the installer, we should be able to replace the present vent with a more capable vent like the ones you're describing with relatively little trouble when the system breaks down. In the meantime though, I think I'll leave the system alone since getting all the air out was a bear and a half.

pitman9

Talk to a rubber roofing contractor

Ask if they have a pitch pan filler. What we used (20 years ago) was a 2 part product that flowed well but then set up into a somewhat flexible rubber. Don't get any on any place you don't want it to stay.

The stuff will seal for a LONG time and will remain flexible. Just make sure the bottom of you flashing is plugged off with soemthing and fill it right to the top.

Constantin

Thanks for the insight...

... is freeze protection a concern for a system that is filled 100% with Tyfocor HTL? Allegedly, the stuff is OK to -40°C, which is pretty chilly.

The present plan is to seal the pipe that runs through the roof 100% with a combination of PU foam and silicone. I'd like to think that the few gallons of water that the system contains would then harmlessly peter down the roof. However, if you think that will not work, I may simply elect to turn off the vent at the top and just leave the de-aerator in the basement to do that job.

Constantin

Will Do!

I am sure that my contractor will have heard of this, and it sounds exactly like what I am looking for. The external Armaflex should then provide the insulation that the system needs...

ALH_4

Hilti

Hilti Fire Foam is somewhat similar to products like "Great Stuff", and it certainly will resist solar hot water temperatures. I'm not sure what the r-value would be.

-Andrew

Constantin

Another update...

... I just received the data sheets for the HTL liquid. It will not freeze to -35°C and it's boiling point (presumably at atmospheric pressure) is 107°C. Since it's under 35psi of pressure, I suspect that would shift the boiling point up a ways, but the header tubing temperature is unlikely to exceed very high temps, no?

In other words, I might be able to get away with ArmaFlex HT tape and Firestop polyurethane in the chase plus a bit of silicone up top to keep eventual leaks out?

Environmental rain and so on is covered by a rain cap I had fabricated for the job. It covers the whole assembly and the pipes. Pics to follow! Cheers!

Joe_55

VENTING

Constantin: What are you doing with that auto-vent on a sealed system? Get that out of there. It does not belong. A mere manual one will suffice. And you speak of some other de-aerator,What is that? there is NO need for that. I have set up my similar system per ITS manufacturers specs. and it has none of these compoments just a manual vent on the collector (which I didn't have to use) This is a sealed system it should have no automatic means of release, Make sure your expansion vessel can accommodate the full charge

RadPro

SOLAR

I like your roof as well is it enviroshake or Eco-shake and are you happy with it????. As for the vaccum tubes you'll be impressed. My bank of 60 tubes are performing as expected beyond my expectations Paul

Bob Gagnon plumbing and heating

I eliminated my vent also Con

I had a little boiling before I had my controls set up, and I lost my prime but a little purging in the besement was all it took. I used a sparco air eliminator in the basement. Consider insulating your pipes twice, it gets cold up here, and cover the armaflex with plastic like at Viessman, to keep the birds and bees from picking at it. Good luck man, and be careful on that roof. Bob Gagnon

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Constantin

Thanks for the advice!

I was simply following the Viessmann installation manual. From what everyone here has told me, I guess I can turn this vent "off". It was very useful though to help purge the system of any remaining entrainment.

Constantin

Thanks for the kind words...

The roofing is so-called DuraSlate, allegedly made from recycled car bumpers and other PVC components.

While the roof was strong enough to take real slate, I felt this material was superior for our application. Real slate is wonderful to behold and not that much expensive material-wise, but 3x more expensive to apply. But the real issue is finding someone qualified to repair the stuff when it breaks. DuraSlate makes it easy by comparison.

DuraSlate is flexible, can be cut with regular cutoff wheels (or sheet metal scissors in a pinch), can be walked on, etc. When used with copper or stainless nails, I'd expect it to last for a very long time. They give a 50-year warranty with the thing, but like most roofing warranties, it isn't worth much beyond the first year. C'est la vie.

David Woycio

venting

I am going to have to disagree with the earlier post to remove the auto air vent. While I agree that they all leak, having one on the highest point of your system can save lots of time purging air from the closed loop glycol system.

Not a fan of glycol systems but sure do work on quite a few. So far this year we have gone through 220 gallons of glycol, mix with 50% water and we are at 440 gallons of fluid. Thats a few recharged glycol systems. Air is the enemy and getting as much out as possible is critical.

Fill the system to slightly higher than design pressure, run the solar circ pump manually for a while until the air is out of the loop. Add more fluid if necessary. After a couple of weeks shut off the valve to the auto air vent.

We use a Braukman auto air vent that has a shut off built into it.

BTW next time use a high temp rubberized roof jack that both pipes will fit through and use a high temp silicone to seal. Insulate over the pipes and seal again....no worries.

A leakproof solution would be to separate the plumbing enough for two roof jacks the correct size. But the way you have it you won't have any problems.

Constantin

Thanks for the tips, MM & Bob!

The loop has been purging itself for a while now. I was quite surprised though to see that Viessmann would spec the de-aerator on the return side (i.e. coming from the collector) not in front of the pump (which is on the supply side). I guess they want the glycol hot but the pump cold.

Many thanks also for your flashing details. Like I said before, my installer had no experience with getting this system installed, and nor do I. However, between the copper cap, the hilti foam, the silicone, and the Armaflex HT tape I have on order, I'd like to think that I'll get it fairly well-insulated. Obviously, I will have to sqeeze something between the copper pipe and the roof penetration, otherwise, I'll have a big radiator up there.

David Woycio

venting

No problem Mr. C. Placing a vent high on the return insures that the collectors will vent. Air in the collecors and/or manifolds can cause all kinds of problems. Also on systems that are diffucult to vent, sometimes just shutting down the circ. pump and allowing the air bubbles to rise to the auto air vent helps in the purge process.

Even thought this is a closed loop glycol system we like to plumb as if it is a drain back. We try to slope all the plumbing to the collectors and back. This helps if you ever have to drain the system and with venting.

Happy solaring!

SVDW

Solar project

Great post & informative as usual! I'm going to put in a vitosol 300 in the next couple of months so I'm interested in seeing how your system works out. I'm located in
Western Mich. so I'm wondering what kind of temps I'll see coming off it in Feb. I'm probably going to pipe it to a tank & plate EX for my indirect & go to an H-coil in my unico to recover >120 temps for supplemental heat to my radient system. Should be fun! Good luck & I look foreward to hearing about your experience w/this system. Looks like you're off to a good start!

Bob Gagnon plumbing and heating

Good luck Steven

Give it hell! take some pictures and let us know how it works out. Bob Gagnon

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